Pyloric ratio: efficacy in the diagnosis of hypertrophic pyloric stenosis.

We sought to define a weight independent, highly sensitive and specific measurement to diagnose hypertrophic pyloric stenosis. A retrospective review of 87 children was performed. We determined the pyloric ratio (wall thickness/pyloric diameter) and its relationship to weight and compared it to standard criteria. The average pyloric ratios in normal children and in those with hypertrophic pyloric stenosis were 0.205 and 0.325, respectively (P < 0.001). A pyloric ratio of 0.27 yielded a sensitivity and specificity of 96% and 94%, respectively. The pyloric ratio maintained a linear relationship to weight in normal patients and those with hypertrophic pyloric stenosis. We conclude the pyloric ratio can be a highly sensitive, specific, and weight independent indicator of hypertrophic pyloric stenosis.

A survey of the ethnic and racial distribution in orthopedic residency programs in the United States.

This study examined the racial and ethnic composition of orthopedic training programs in the United States. A questionnaire was mailed in January 1995 to chairpersons at 159 orthopedic programs in the United States. Eighty-nine (56%) responses were received. The distribution of orthopedic residents and fellows was as follows: white non-Hispanic, 84.2%; Asian, 6.6%; African American, 3.6%; Native American, 2.2%; Puerto Rican, 1.2%; Mexican American, 0.8%; and other Hispanic, 1%. African Americans and Hispanics were under-represented in orthopedic training programs compared with their numbers in the general population. The percentage of residents in these two minority groups also were below goals established by the Council on Graduate Medical Education and the US Government's Healthy People 2000 report. In contrast, Native Americans and Asians were overrepresented. If racial balance is to be achieved in orthopedics, new incentives must be created to encourage more African Americans and Hispanics to enter orthopedic residency training programs.

Repair of full-thickness defects in the femoral trochlea of dogs after trochlear arthroplasty.

Trochlear arthroplasty was performed on one stifle in each of 18 Greyhounds; their contralateral pelvic limbs and the pelvic limbs of 2 dogs treated with sham surgery were controls. At 2, 4, 8, and 16 weeks, radiography, glycosaminoglycan histochemical analysis, histologic examination, and scanning electron microscopy of the trochlear surface were done. All dogs used the limb and walked without an observable limp within 2 weeks after surgery. Radiography at euthanasia did not reveal degenerative changes. Well-vascularized, highly cellular, loose fibrous connective tissue was reorganized with time into a dense fibrous connective tissue covering the entire wound. Scanning electron microscopy revealed that the replacement tissue surface was rough, torn, and debris-covered. Differential histologic staining established that change to fibrocartilage had begun deep within the replacement tissue. Histochemical analyses corroborated those observations.

Ultrasonographic and biometric evaluation of the eye and orbit of dogs.

The normal B-scan ultrasonographic anatomic features of the eye and orbit of mesocephalic and dolichocephalic dogs were described. The B-scan appearance of ocular and orbital structures correlated well with the visual morphologic features of the specimens. The eyes of mesocephalic and dolichocephalic dogs were measured by use of ultrasonographic methods; those measurements were compared with direct measurements of the specimens. The 2-tailed Student t-test was used for all statistical analyses (P = 0.05). Measurements made included mid-cornea to anterior lens surface, lens thickness, vitreous body (posterior lens surface to retina), and axial globe length. The A-scan measurements of all 4 ocular distances were significantly different, compared with direct measurements. The B-scan measurements of mid-cornea to anterior lens surface, lens thickness, and vitreous body were significantly different from direct measurements; however, there was no significant difference between B-scan and direct measurements of axial globe length. There was no significant difference between A- and B-scan measurements. These findings suggest that A- and B-scan measurements are similar and that B-scan measurements are reasonably accurate for axial globe determination. Several variables were compared by B-scan and direct measurement methods. The axial globe length of dolichocephalic dogs was significantly longer than that of mesocephalic dogs. The axial globe length of male and female dogs was not significantly different in mesocephalic or dolichocephalic dogs. There was no significant difference in the axial globe length of right and left eyes in mesocephalic or dolichocephalic dogs.

Histochemical study of the anulus fibrosus in normal canine caudal cervical intervertebral discs.

A qualitative assessment of glycosaminoglycans (GAGs) in the non-chondrodystrophoid canine cervical anulus fibrosus was performed using the Alcian blue/critical electrolyte concentration staining technique. Estimates of GAG concentration were deduced for two groups of dogs (average age four and eight years) by determining the hyaluronic acid, chondroitin sulphates and keratan sulphate 'alcianophilic indices'. Keratan sulphate was the predominant GAG in the four-year-old group of dogs. The concentration of keratan sulphate was equal to that of chondroitin sulphates in the eight-year-old group and the total GAG concentration was decreased. This qualitative assessment indicated that the concentrations of keratan sulphate decreased and chondroitin sulphates increased between four and eight years of age. Similar conclusions have not been reported for anuli in the thoracic and lumbar regions of the canine spine.

Morphometric studies of the epidermal-dermal junction in the rat ear: some effects of experimental friction on epidermis and anchoring fibrils.

The aim of this investigation was to determine whether, following the application of experimental friction to the skin, qualitative an quantitative differences could be induced in the epidermis and in anchoring fibrils. The skin of rat ears was subjected to repeated mild fractional stimulation with a rotating bristle brush moistened with saline thrice weekly for three weeks, untreated ears being used as controls. A stratified random sampling design was followed for the morphometric analysis of interfollicular epidermis. With the light microscope, the lengths of the granular cell/keratin (BGK) and epithelial-connective tissue (BEC) junctions were measured using an image analyser, as was the epithelial thickness (T). The ratio BEC/BGK provides an index of the degree of irregularity of the epithelial-connective tissue junction. Using electron microscopy, the numbers of anchoring fibrils per unit length of lamina densa (NB) were determined using stereological intersection counting. There are no significant differences in BEC/BGK or T between control and experimental groups, but anchoring fibril frequency NB increased from 10.29 micrometers in control epidermis to 18.9 micrometers in friction-treated epidermis. It is concluded that a mild frictional stimulus which fails to produce significant alterations in epidermal thickness can produce a marked increase in anchoring fibril frequency. This response may reflect a functional alteration associated with increased mechanical loading, in which epidermal-dermal adherence is augmented by either synthesis of anchoring fibrils or their insertion into the lamina densa.

Ultrastructural changes associated with the mineralization of deer antler cartilage.

The maturation and mineralization of deer antler cartilage were investigated ultrastructurally by using enzymatic digestions and subsequent staining with ruthenium red (RR) or phosphotungstic acid (PTA). RR staining of matrix granules was observed in the immature prechondroblastic matrix and became more intense as the cartilage matured into a mineralized tissue. The granules got larger and more numerically dense in the mature matrix. There were matrix granules that coalesced around matrix vesicles or remnants of such in the mineralized zone. These granules were observed after demineralization, and they were RR and acidic PTA-positive (they were not susceptible to hyaluronidase nor trypsin digestion, however). It appears that the granules were modified such that the matrix vesicle formed a centralized nidus for mineralization. The growth of hydroxyapatite crystals along matrix granules (which in this zone may or may not represent proteoglycan monomers) may have caused the coalescence. Microfibrils associated with matrix granules probably represented the hyaluronic acid core of the large proteoglycan complexes because of their susceptibility to hyaluronidase digestion.

Characterization of developing antler cartilage matrix. I. Selected histochemical and enzymatic assessment.

Biopsy samples of the main beams and tines were obtained from the antlers of mature Rocky Mountain mule deer (Odocoileus hemionus hemionus) during the rapid phase of the antler grow-th cycle. The samples were studied using histochemical and enzymatic techniques for the demonstration of mucosubstances. The reserve mesenchyme contained chondroitin 4- and 6-sulfates, hyaluronic acid and sialic acid. During prechondroblastic and chondroblastic differentiation, some strongly sulfated mucopolysaccharides were complemented by low molecular weight or incompletely sulfated chondroitin 4- and 6-sulfates. During maturation of the cartilage strongly anionic mucopolysaccharides (possibly heparin, keratan and/or dermatan sulfates) were present in the general matrix and especially prominent along the capsular margins. Calcification foci, beginning initially in the mid-trabecular regions and eventually extending to the trabecular margins, were highly reactive for mucosubstances and were enzyme-resistant. This histochemical study establishes the cartilaginous nature of the developing deer antler, defines some of the mucosubstance constituents involved in the chondrogenic and calcification process, and confirms the utility of the antler as a model for chondrogenic and calcification studies.

Characterization of developing antler cartilage matrix, II, An ultrastructural study.

Cartilage from the main beams and tines of deer antler was examined with the electron microscope. The material studied included prechondroblastic, chondroblastic and chondrocytic matrices. Exdysial microfibrils (5-10 nm in diameter) were observed in the matrix of the prechondroblastic zone. These microfibrils and associated amorphous material were continuous with electron-dense material that probably represented extracellular units of collagen polymers. Matrix (proteoglycan) granules were first observed in the chondroblastic zone. They stained positively with colloidal iron and therefore probably represented proteinpolysaccharides. The matrix granules of the chondroxytic (unmineralized and mineralized) zone were twice the diameter of those in the chondroblastic zone. Matrix vesicles were present in all three stages of development. They were in contact with cellular extensions and also arose directly from cell membranes in the immature zones. As in somatic mineralizing cartilage, these vesicles served as the foci for early mineralization. The initial mineralization process was associated with the membrane of the vesicles.