The influence of variations in electrolyte concentration on skin potential level and response amplitude

The application of electrolytes of low concentration to the palm causes hydration of the epidermis with swelling of the skin, closure of the sweat gland pores, and reduction of skin potential level (SPL). Solutions of high concentration are known not to produce poral closure. Previous reports of increases in SPL with increased concentration of electrolyte did not control for possible effects of hydration associated with differences in concentration. The experiments reported here compared the effects of varying concentration with and without holding hydration constant. The results indicated that the effect of concentration on both positive and negative skin potential response amplitude can be attributed to hydration, whereas the effect on SPL is not influenced by hydration. The effect of concentration on SPL was the same whether measured during rest or during periods of considerable sweat gland activity. This last finding is difficult to interpret in terms of the traditional assumption that the membrane responsible for the concentration-potential effect lies deep in the epidermis, and it was suggested that the membrane may be located in the upper sweat gland duct.     

Metabolic depression and myocardial potassium

Summary The action potential duration (APD) of guinea pig atrial muscle responded qualitatively to metabolic depression and altered glucose concentration as shown previously for papillary muscle. Both preparations lost potassium and gained sodium during 8 h anoxic incubations and these changes were partially prevented by 50 mM glucose. Experiments with potassium⁴² indicated that anoxia-induced loss of potassium was not primarily due to an increased efflux but to a decreased influx. Stimulation did not increase potassium⁴² efflux from atria but caused some increase in potassium loss. The ATP content of atria and ventricular muscle decreased rapidly during anoxic incubation but was maintained at a significantly higher level in the presence of 50 mM glucose. Since muscle potassium levels following 8 h of anoxic incubation were incompatible with observed resting potentials, the results support the concept of either an electrogenic sodium pump or the intracellular compartmentalization of potassium. In addition, the anoxia-induced reduction of action potential duration does not appear to be associated with an increase in potassium⁴² efflux.This work was supported by grants from the Medical Research Council of Canada and the Canadian Heart Foundation.     

Fine-needle aspiration biopsy of multiple myeloma in a patient with renal-cell carcinoma: A case report

A case of multiple myeloma diagnosed by fine-needle aspiration (FNA) biopsy and confirmed by laboratory studies in a patient with a history of renal-cell carcinoma is presented. The patient was diagnosed with renal-cell carcinoma of the right kidney and a radical nephrectomy was performed. Eighteen months after this diagnosis was made, the patient developed chest wall pain and was found to have osteolytic bone lesions of the ribs and vertebral bodies. FNA of an osteolytic rib lesion disclosed multiple myeloma. Additional laboratory studies confirmed the diagnosis of multiple myeloma. This case report demonstrates the value of FNA as a diagnostic tool for the follow-up of cancer patients, the subsequent discrimination between metatastic lesions and a second primary malignancy, and the cytology of multiple myeloma.     

SEM of the proximal tubule of the adult rabbit kidney

The present study utilizes the scanning electron microscope (SEM) to reveal the surface morphology of proximal tubular cells and the parietal cells of Bowman's capsule of the adult rabbit nephron. To facilitate the examination of the basal surface of these cells, proximal tubules were dissected free and treated with collagenase to remove the basememt membrane. Other blocks of tissue were cryofractured to expose the lateral cell surfaces of the proximal tubules. Our investigation has shown that the lateral and basal surfaces of both the convoluted and straight segments of the proximal tubule have numerous processes. However, the arrangement and degree of branching is distinctly different in the two segments. The convoluted segment has large lateral ridges which form at the base of the microvilli and fan out to divide into lateral-basal processes. Many of the lateral-basal processes reach the basement membrane intact, interdigitating with complementary processes from adjacent cells. However, some of the lateral-basal processes branch into short, knobby projections (basal villi) which may also reach the basement membrane. Patches of basal villi are interspersed between broad regions of interdigitating lateralbasal processes. Therefore, in the convoluted segment, the lateral-basal processes form the major part of the basal cell surface. In tubular cells of the pars recta, unlike convoluted tubular cells, the majority of the ridges remain unbranched and pass directly to the basal surface where they divide into elaborate basal villi. Thus the basal surface of the pars recta cells is highly complex, appearing leaf-like, being a composite of numerous basal villi with a few lateral ridges. The basal surface of some parietal cells of Bowman's capsule have parallel ridges, which results in patches of striations.     

Production of anti-NC1 antibody by affected male dogs with X-linked hereditary nephritis: A probe for assessing the NC1 domain of collagen type IV in dogs and humans with hereditary nephritis

Summary Some patients with hereditary nephritis (HN) who have received a renal transplant have been shown to form antibody with specificity for the NC1 domain of collagen type IV, a major constituent of glomerular basement membranes (GBM). We attempted to duplicate this phenomenon in a family of dogs with X-linked HN, a model for human X-linked HN, by immunizing affected male dogs with normal dog NC1 domain. A collagenase digest was prepared from normal dog GBM, the NC1 domain was separated into dimer (50 kDa) and monomer (24 kDa and 26 kDa) components by SDS-PAGE, and injected into two affected male dogs. Antisera obtained from both dogs contained antibody which reacted with the NC1 domain of dog and human GBM by a plate-binding radioimmunoassay, bound to the dimer and 26 kDa monomer bands by Western blotting, and staining dog and human GBM by immunofluorescence (IF). The affected male dog antiserum reacted equally by radioimmunoassay with the NC1 domain isolated from GBM of unaffected, affected male, and carrier female dogs in the family with X-linked HN, and bound by Western blotting to dimers and the 26 kDa monomer band of the NC1 domain of GBM in each group of dogs. However, the affected male dog antiserum differentiated these dogs by IF; it produced global staining of GBM of unaffected dogs, failed to stain GBM of affected male dogs, and produced segmental staining of GBM of carrier female dogs. Absorption of the affected male dog antiserum with normal dog NC1 domain eliminated the staining of dog GBM by IF, whereas staining persisted after absorption with affected male dog NC1 domain. The abnormal staining patterns of GBM seen by IF in the affected male and carrier female dogs and the results of the absorption studies imply an abnormality of one or more determinants in the 26 kDa monomer band of the NC1 domain of their GBM. Amino acid sequencing of this band identified the 1(IV) chain of collagen type IV, a finding that has implications for the pathogenesis of canine X-linked HN. Absent and segmental staining respectively were also seen by IF in GBM of a male and female patient with HN, using the affected male dog antiserum. Thus, the results obtained in affected male and carrier female dogs with X-linked HN may also be relevant to patients with this disease.     

Cystic fibrosis: Synthesis of ciliary inhibitor by amniotic cells

The presence of a ciliary inhibitor in media of cultured amniotic cells obtained from a fetus heterozygous for cystic fibrosis has been observed by the oyster gill cilia assay. The chromatographic fraction containing the inhibitor corresponded to eluted fractions chromatographed from cystic fibrosis fibroblast media and serum. An analogous chromatographic fraction from media of cultured amniotic cells from two proportedly normal fetuses did not inhibit cilia. The chromatographic fraction from media of cultured amniotic cells of a fetus at high risk for cystic fibrosis did not inhibit ciliary activity. Serum was collected from this baby seven weeks after birth and also did not inhibit ciliary action, indicating a homozygous normal genotype. These observations may lead to the development of an antenatal test for cystic fibrosis.     

Molecular identification of a novel deltaproteobacterium as the etiologic agent of epizootic bovine abortion (foothill abortion)

Epizootic bovine abortion (EBA) is endemic in California's coastal range and the foothill regions of the Sierra Nevada, where it has been the primary diagnosed cause of abortion in beef cattle for >50 years. Investigation of these losses has defined a specific fetal syndrome characterized by late-term abortion or birth of weak or dead calves. Although the unusual clinical presentation and unique fetal pathology associated with EBA have been recognized since the 1950s, the identity of the etiologic agent is unknown. In this study, suppression-hybridization PCR was used to identify a fragment of the 16S rRNA gene of a previously undescribed bacterium in thymus tissue derived from affected fetuses. Phylogenetic analysis revealed that this pathogen was a deltaproteobacterium closely related to members of the order Myxococcales. A specific PCR was subsequently developed to detect the presence of this bacterium in DNA extracted from fetal thymuses. Using histopathology as the definitive diagnosis for EBA, this PCR demonstrated 100% specificity and 88% sensitivity. The bacterium was also detected in the argasid tick Ornithodoros coriaceus, which is the recognized vector of EBA. These data imply a close association between this novel agent and the etiology of EBA.     

Nitric oxide synthase immunoreactivity of interstitial cells of Cajal in experimental colitis

OBJECTIVE: There is functional and morphological evidence that interstitial cells of Cajal (ICC) may play a role in nitric oxide (NO) dependent signal transduction. However, little is known about the nitric oxide synthase (NOS) containing ICC during inflammation. MATERIALS AND METHODS: Immunocytochemical methods were used for the ultrastructural localization of NOS1-containing ICC in the wall of the colon of rats in experimental colitis. RESULTS: Large numbers of NOS immunoreactive (IR) nerve terminals were found in very close vicinity to smooth muscle cells as well as to blood vessels. IR nerves were found in close relationship with the ICC. The gap between the NOS IR nerve fibers and the membrane of smooth muscle cells and of ICC was 20-250 nm. In experimental colitis the number of NOS IR nerve fibers slightly decreased, however, large numbers (24%) of the ICC became IR for NOS. In the noninflamed area and in the controls, all these cells were immunonegative for NOS. CONCLUSIONS: Our light- and ultrastructural study suggests that some of the ICC can also synthesize NO, at least during inflammation. Therefore the change in the number and structure of ICC could play an important role in the pathogenesis of a variety of motility disorders.