Associate Professor, Charles R. Drew University of Medicine and Science
This reductionist move is in service of generating stable antibiotic resistance argument buy generic trozocina 250mg on line, statistically credible population averages topical antibiotics for acne while pregnant discount trozocina online master card. There are problems in including too much (what turns out antibiotic resistance humans trozocina 500 mg lowest price, in the fullness of time bacteria 24 discount generic trozocina uk, to be "noise") and too little (missed "signal"). Recall the years of our examining peptic ulcer surgery specimens and ignoring the Helicobacter organisms; (2) the observations have to be preprocessed into a computer digestible form, usually nonfuzzy; (3) a similarity measure must be selected from a large number of workable metrics. The "nearest neighbor" looses meaning with a modest increase in the dimensionality of the data. That is, as the dimensionality of the phenospace increases the ratio of the distance to the nearest neighbor and the distance to the most distant neighbor asymptotically approaches unity. There is much debate about who should be integrating this growing, complex quantity of patient information. Not surprisingly, some pathologists argue that it should be the pathologist [31, 32]. However, this issue may be settled, there is no question that light microscopy is an essential organizing level in cancer management, and expertise in histopathology will be required no matter what the future holds for the moleculargenetic dimensions of neoplasia. It is not only reasonable but necessary for pathologists to resist the methodological imperialism de jour. From vagueness in medical thought to the foundations of fuzzy reasoning in medical diagnosis. Unguided statistical intuitions are notoriously flawed and keeping track, without assistance, of the large number of conditional probabilities involved in a practical decision-making problem is impossible. The evaluation of the tsunami of evidence from clinical trials, from genomic studies, requires, as we have seen, highly specialized knowledge from a variety of disciplines for which pathologists have little training. Grade 1 peritoneal serous carcinomas: a report of 14 cases and comparison with 7 peritoneal serous psammocarcinomas and 19 peritoneal serous borderline tumors. Future directions in quantitative pathology: digital knowledge in diagnostic pathology. Decision support systems for morphology-based diagnosis and prognosis of prostate neoplasms: a methodological approach. Systems pathology: a paradigm shift in the practice of diagnostic and predictive pathology. Prognostic immunohistologic markers in human tumors: why are so few used in clinical practice The evolution of tumor biology: seeking a balance between gene expression profiling and morphology studies. Costa and Whitaker, pathologists generally believe that most information used in our daily practice is based on sound observations, the results of evaluating tissue and other body samples with the latest analytical methods, and the A. Yet, if we review the current literature from an epistemological point of view and using the systematic approach described in this chapter, one can argue that the quality of future pathology publications could be enhanced by the use of more precise methodology that explicitly lists the objectives of each study, considers the limitations resulting from the characteristics of the materials being investigated in the development of conclusions, and analyzes the results with an eye toward developing information that is useful for the evaluation, diagnosis, and treatment of individual patients. It promotes the analysis of the nature and limitations of various conceptual paradigms and observational methods used for the acquisition and interpretation of new information. What is the applicability of the study results for the evaluation and diagnosis of my individual patients The various comments are not intended to judge on the quality of the articles selected for review, but to explore methodological characteristics and details in an effort to evaluate the validity of the results of each study and their applicability in current pathology practice. However, knowledge about elusive "truths" frequently evolves as a result of an iterative process where new information poses new questions, leading to the generation of new hypotheses that stimulate the collection of additional data that update previous knowledge. In addition, knowledge is influenced by beliefs held as a result of tradition, education, and various cultural, psychological, and sociological factors. Beliefs can alter the perception of observations and influence the interpretation of data resulting in a variety of biases that can distort the validity of presumably scientific information. However, as expert reviewers often have their own preconceptions and biases, the fact that new information has been reported in the peer review literature offers no absolute guarantee about its scientific value, leaving the reader with the personal responsibility to evaluate the validity of published data [30]. In addition, practicing pathologists are likely to read the literature with these two general questions in mind: do these conclusions apply to my patients The questions listed in the table can then be expanded to formulate the more specific queries listed in other tables. Does the Study Include Comprehensive and Unbiased Background Information: Narrative Reviews Versus Systematic Literature Reviews An initial step during the evaluation of the validity of the content of pathology publications is to identify the methodology used for the selection of pertinent background information. Such information from previous literature is frequently used to justify 11 Evidence-Based Approach to Evaluate Information Published in the Pathology Literature 191 the hypothesis being tested in a study, evaluate the results, formulate conclusions, and/or integrate them with previous knowledge. The methodology used to select background information is particularly pertinent when evaluating the content of review articles. Authors, presumably based on their own experience and professional judgment, pick and choose selected information from a variable number of references usually found in the Pubmed database of the National Library of Medicine and do not explain why certain publications were included, while others may have been excluded by design or neglect.
Numerous orifices of urethral glands lie in the dorsolateral portion of the distal third of the urethra best antibiotics for sinus infection doxycycline purchase generic trozocina online. Later in development bacteria pseudomonas purchase trozocina 500 mg line, pitlike depressions (lacunae) that are sometimes lined with glandular epithelium virus encrypted files quality 250 mg trozocina, appear in the middle and proximal urethra bacteria background buy trozocina 500mg fast delivery. The urethral orifice with its slightly protruding margins lies in the vestibule on the fourchette just above the vaginal introitus and about 2. Thin-walled tortuous veins running longitudinally under the epithelium are interspersed among elastic fibers; they are especially prominent in the proximal third, forming a proximal venous plexus and, in the distal few millimeters, the distal venous plexus. This arrangement probably plays a role in urethral closure, supplementing the seal produced by intrinsic urethral softness. Numerous small arteriovenous aneurysms appear in the plexuses during the fertile period of life. The urethral mucosa is composed of pseudo-stratified columnar epithelium, with some transitional epithelium near the bladder and stratified squamous epithelium near the external meatus. The hormonal status of the subject plays an important role in epithelial type and distribution. By scanning electron microscopy, the cells of the more proximal region show microplicae; the more distal cells have microvilli like those of the vagina. The lamina propria (submucosa) contains numerous elastic fibers that are partially arranged in circular but principally in longitudinal directions. Small bundles of smooth muscle may be found in the urethral crest, representing an extension of the superficial trigone. Urethral Sphincters the muscular, and consequently the functional, anatomy of the female urethra has been extensively studied, with each student tending to contribute an individual interpretation. At the present time it is possible to get only a general consensus from this work. The urethral sphincters are the smooth muscle internal sphincter and the striated urogenital sphincter. Transitional epithelium lines the proximal third and nonkeratinizing stratified squamous epithelium lines the distal two-thirds of the female urethra. The lamina propria is richly vascular and is infiltrated in this case by abundant chronic inflammatory cells. Elastic fibers, composing a very small proportion of the total mass, play a minor role but help prevent overdistention with resulting tissue damage. The smooth muscle sphincter surrounds a layer of spongy tissue, the spongiose erectile tissue (not homologous with the spongiosus in the male), which is composed of veins interspersed with smooth muscle and elastic fibers. Continence is maintained by the combined efforts of the smooth and surrounding striated urethral musculature that maintain the mucosal lining in apposition. The function of the longitudinal fibers appears to be to shorten the urethra and thereby increase its diameter for voiding. The function of the relatively few circular elements may be to allow radial distention during voiding and to resist distention at other times; it is doubtful whether they have sphincteric capability. Of interest is the possibility that the two layers may have a different autonomic innervation. Innervation is provided by cholinergic terminals, which are very similar to those of the detrusor. The larger nerves are associated with muscle bundles and the smaller ones with individual muscle fibers. The adrenergic terminals in the female urethra and bladder neck are sparse, with a density similar to that found in the male bladder neck. The smooth muscle sphincter has two coats, a dominant inner longitudinal coat and a sparse outer semicircular coat, that invest it from the neck of the bladder to just within the meatus. The inner longitudinal layer joins the inner longitudinal layer of the detrusor but is made up of much more delicate bundles. The muscle fibers are held together by elastic tissue and a large amount of firm collagen. The middle semicircular layer (probably from the outer longitudinal layer of the detrusor) appears to form loops at the bladder neck and provides fibers organized in a semicircular fashion down the urethra. The circular coat is more prominent in the mid-urethra, where the smooth fibers mix with the striated fibers of the external sphincter. Both coats decrease in thickness as they approach termination distally in the dense collagen ring immediately proximal to the meatus. In comparison with those in the male, the circular smooth muscle components are much less well defined, there being no structure in the female resembling the preprostatic sphincter in the male. Collagen forms a major component of the urethra, occupying more of the tissue mass than does the smooth muscle. It, too, is oriented with the smooth muscle in both the longitudinal and circular layers. The collagen fibers associated with the circular muscle fibers are considered an important component of passive closure of the urethra, especially because they require no energy to maintain tone. A second is the urethrovaginal sphincter disposed about the more distal portion of the urethra and the vaginal vestibule. The third is a urethral compressor that passes over the ventral side of the urethra. External Urethral Sphincter the striated urethral sphincter, as in the male, is embryologically and anatomically separate from the surrounding striated musculature. The elements are not differentiated in the fetus, but they subsequently differentiate in the female as they do in the male, events that are described in Figure 14-9. The striated urethral sphincter encircles the smooth muscle sphincter of the urethra from the bladder base to the perineal component without distinction of a urogenital diaphragm. The most dense collection of striated muscle fibers is found in the midurethra in the area of the high-pressure zone found on urodynamic study. Some fibers continue proximally to the bladder neck, and some connect with the vaginal wall or to the endopelvic fascia.
These join a single or double superficial dorsal vein that drains into either saphenous vein treatment for dogs collapsing trachea generic 250 mg trozocina with visa, usually that on the left antibiotic resistance in america order trozocina online now. It may also pick up some blood from the scrotum and spermatic cord before making the connection antibiotic resistant virus in hospitals best purchase for trozocina. An intermediate drainage system virus on mac computers order genuine trozocina, composed of the deep dorsal vein and the circumflex veins, drains the glans penis, the corpus spongiosum, and the distal two-thirds of the corpora cavernosa. Many small veins leave the glans penis via the retrocoronal plexus to enter the deep dorsal vein that runs in a groove at the junction of the two corpora. The deep dorsal vein then passes through a space in the suspensory ligament and between the puboprostatic ligaments to drain into the prostatic plexus, where multiple bicuspid valves are present near the entry of the vein. The deep dorsal vein may be multiple and may, in turn, connect with the superficial system before joining the plexus. The prostatic plexus drains into the vesical plexus and thence into the internal iliac veins. The deep drainage system is composed of the cavernous veins, the bulbar veins, and the crural veins. Blood collected from the sinusoids of the proximal third of the penis by the emissary veins drains directly into cavernous veins at the periphery of the corpora cavernosa, forming the principal drainage system for the corpora. In addition, the capillaries that form a second circulatory system drain into the subalbugineal venular plexus and thence into the emissary veins. The cavernous veins unite between the crura into one or two large thin-walled main cavernous veins that lie under the cavernous arteries and nerves, making them less readily accessible for surgical ligation. The cavernous veins, in turn, run between the bulb and the crus to drain into the internal pudendal vein, then to the internal iliac vein. Bicuspid valves are uniformly present, although they may not be competent in older men. Crural veins, which are few in number, arise from the dorsolateral surface of each crus and unite to drain into the internal pudendal vein, with some contribution to the prostatic plexus. The bulb itself is drained by the bulbar veins, which empty into the prostatic plexus. The routes of blood circulation during erection and detumescence are outlined in Table 16-4. Crural vein to internal pudendal vein Vein of the bulb to periprostatic plexus to internal pudendal vein Retrocoronal venous plexus to deep dorsal vein to periprostatic plexus Lymphatic Drainage of the Penis and Urethra the surface of the glans penis has three superposed networks, one in the papillae, another in the superficial mucosal layer, and a third beneath the other two. The collecting trunks converge on the frenulum, where they pick up collectors from the urethral mucosa. One to three trunks then pass around to the dorsum in the coronal sulcus to join those from the opposite side. One or more major collecting trunks running with the deep dorsal vein carry the lymph to the region of the suspensory ligament where they join the presymphyseal plexus. Two or three trunks run from this plexus to the superficial inguinal nodes along either a femoral or an inguinal path. Delicate preputial lymphatics arise both from the inner and, more abundantly, from the outer surfaces of the prepuce. As they run proximally, they anastomose and curve to become confluent on the dorsum. The penile skin proper is drained by lymphatics that run from the median raphe obliquely around the penis to join the dorsal lymphatic channels already draining the prepuce. At the base of the penis, branches from the skin and prepuce connect with a presymphyseal plexus before passing right and left to join trunks draining the perineal and scrotal skin. The joint trunks run with the superficial external pudendal vessels to drain into the superficial inguinal lymph nodes, especially the superomedial ones. Some drainage occurs through the femoral route, passing into the femoral canal to enter a deep node there, to enter the node of Cloquet, and also to enter a medial retrofemoral node. For the inguinal route, a single trunk approaches the inguinal canal below the spermatic cord to reach the lateral retrofemoral node. Thus, the lymphatics of the penile skin empty through the superficial lymphatic drain- age system into the superficial inguinal nodes, particularly the superomedial group, whereas the glans and penile urethra drain into the deep inguinal nodes and the presymphyseal nodes and, occasionally, into the external iliac nodes. Somatic Innervation of the Penis the somatic nerve supply comes principally from spinal nerves S2, S3, and S4 by way of the pudendal nerve. There, it gives off the perineal nerve with branches to the posterior part of the scrotum or to the labia majora in the female and the rectal nerve to the inferior rectal area. It continues as the dorsal nerve of the penis as it runs over the surface of the obturator internus and under the levator ani on the medial side of the internal pudendal vessels that lie within the obturator fascia. The dorsal nerve runs on the deep layer of the so-called urogenital diaphragm, where it gives off a branch to the crus. It then passes through the deep transverse perineal muscle to course on the dorsum of the penis. It is accompanied along the dorsolateral surface of the penis by the dorsal artery of the penis and terminates in multiple branches in the glans. In epispadias and exstrophy, the dorsal nerves are displaced laterally in the middle and distal portions of the shaft; they become anterolateral only proximally. The main cutaneous nerve supply to the penis and scrotum comes through the dorsal and posterior branches of the pudendal nerve, but the anterior portion of the scrotum and the proximal part of the penis are supplied by the ilioinguinal nerve after it leaves the superficial inguinal ring. Autonomic Innervation of the Penis the sympathetic nerves arise from the lumbar nerves L1 and L2 and the parasympathetic nerves from sacral nerves S2, S3, and S4.
In infants and obese adults infection fighting foods generic 500mg trozocina mastercard, a fold of skin runs transversely above the skin crease at the bend of the thigh antibiotics for sinus infection and strep throat order trozocina 500 mg free shipping. This marks the lower border of the thickest part of the abdominal panniculus and is a useful crevice in which to hide an incision can you take antibiotics for sinus infection while pregnant purchase 100 mg trozocina with amex. In fact antimicrobial floor mats purchase cheapest trozocina and trozocina, the lines of skin tension run transversely and should be followed to favor healing of the wound, because the surrounding skin flaps can always be moved to allow surgical exposure of all parts of the groin. Although an attempt is made to divide the superficial fascia into a superficial layer and a deep or membranous layer, the continuities are not precise, because some layers become attenuated and others acquire local importance. The superficial layer of the superficial fascia (Camper) is areolar tissue with its contained fat. This layer passes over the inguinal ligament to continue as the superficial fascia of the thigh. It is also continuous with the superficial fascia of the penis (often called the dartos layer). It descends into the scrotum with that of the areolar outer covering of the spermatic cord, the dartos proper, where the areolar tissue picks up nonstriated muscle fibers to become the dartos muscle. The layer then passes posteriorly to join the superficial layer of the superficial fascia of the perineum. The superficial epigastric vein and artery arise from the anterior surface of the femoral vein and artery 1 cm below the inguinal ligament and run across the line of an inguinal incision beneath the superficial layer to the level of the umbilicus. An incision through the neck of the scrotum may encounter the superficial external pudendal vessels as they cross from the fossa ovalis to supply the penis and scrotum. The deep or membranous layer of the superficial fascia (Scarpa) is found in the groin as a distinct compact layer, but it becomes less identifiable over the upper portions of the flank and abdomen and may not be found in obese individuals. It is loosely connected to the innominate fascia of Gallaudet, which is the investing fascia overlying the external oblique aponeurosis. The membranous layer is firmly connected to the linea alba and to the symphysis pubis, contributing to the fundiform ligament. The superficial inguinal pouch (Denis Browne) is a potential space between the membranous layer and the innominate fascia. The pouch lies lateral to the external ring and provides a space in which a cryptorchid testis may be found. This ring is not to be confused with the external inguinal ring, which lies higher and is rarely palpable in the absence of a hernia. It is continuous over the penis as the superficial fascia of the penis, the dartos layer, and it follows the spermatic cord into the scrotum as the membranous layer of the superficial fascia (dartos tunic). Bony Pelvis Before describing the soft tissues, the bony surfaces and landmarks of the public portion of the pelvis are presented as a framework for attachment of the fascial structures about the inguinal canal. The lateral head of the rectus abdominis arises from its lateral part; the medial part of the rectus crosses its medial part before attaching to the symphysis and adjacent pubis. The pubic tubercle lies near the medial end of the pubis and is an important landmark in surgery of the groin because it indicates the medial attachment of the inguinal ligament. The joint between the pubic bones, the pubic symphysis, has a thickness of 2 to 3 mm and is composed of hyaline and fibrous cartilage. It is connected by a heavy anterior pubic ligament and a smaller posterior pubic ligament, structures that are more likely to pull off from the bone rather than rupture. External Oblique Layer Each of the three muscles of the anterior abdominal wall is covered on both sides with investing fascia. The layer covering the external surface of the external oblique, the innominate fascia of Gallaudet, is the thickest and becomes the fascia lata in the thigh. The internal surface of the muscle has a thinner fascial coat and both the inner and outer fascias fuse at the inferior, free border, where the external oblique forms the inguinal ligament. The aponeurosis is also attached medially to the upper border of the pubic symphysis and to the pubic crest as far as the pubic tubercle. It forms the anterior wall of the inguinal canal, supplemented laterally by fibers of the internal oblique aponeurosis that attach to the lateral part of the inguinal ligament. The external spermatic fascia results from fusion of the innominate fascia and the fascia associated with the internal surface of the external oblique and its aponeurosis. It is important surgically during exposure of the spermatic cord: If this fascia is incised along with the underlying external oblique aponeurosis to the point where its sheath widens near the upper pole of the testis, the scrotal contents, even if enlarged, may be drawn into the wound. The superficial inguinal ring is the most medial of the three inguinal rings (superficial, external, and internal) that provide passage for the spermatic cord while preventing herniation of the peritoneum and its contents. Its sides are the medial and lateral crura formed by the edges of the external oblique aponeurosis as that structure splits to join the crest. The lateral edge, as the inferior or lateral crus, is the inguinal ligament itself reinforced by the intercrural fibers that come from the innominate fascia. The intercrural fibers run at right angles to the fibers of the aponeurosis and may arch over the superficial ring. Inguinal Ligament the inferior margin of the aponeurosis of the external oblique extends between the anterior superior iliac spine, where it is attached to the iliopsoas fascia, and the pectineus fascia at the pectineal line on the inner aspect of the pubis. The aponeurosis becomes somewhat thicker as it arches over the femoral nerve, vessels, and canal and folds internally on itself before ending as a free edge. This inward fold forms a shelf along its inner aspect, the inguinal ligament (Poupart). The ligament is rounder laterally but becomes flatter medially as it joins the pubic tubercle. The fibers of the external oblique aponeurosis change their oblique course to a more transverse direction to follow the line of the ligament.
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