Biomedical subjects
Publications and source records attributed to S Hoffman.
A case is described of prolonged neuromuscular block in a patient who was given the muscle relaxant vecuronium followed by bolus injections of the antibiotics gentamycin and clindamycin.
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The sequential appearance of the extracellular matrix (ECM) protein, cytotactin, was examined during development of the chicken embryo by immunohistochemical techniques. Although cytotactin was identified as a molecule that mediates glia-neuron interactions, preliminary immunohistochemical localization of the molecule suggested that it was an ECM protein with a widespread but nonetheless more restricted distribution than either fibronectin or laminin. In the present study, it was found that cytotactin is first present in the gastrulating chicken embryo. It appears later in the basement membrane of the developing neural tube and notochord in a temporal sequence beginning in the cephalic regions and proceeding caudally. Between 2 and 3 d of development, the molecule is present at high levels in the early neural crest pathways (surrounding the neural tube and somites) but, in contrast to fibronectin and laminin, is not found in the lateral plate mesoderm or ectoderm. At later times, cytotactin is expressed extensively in the central nervous system, in lesser amounts in the peripheral nervous system, and in a number of nonneural sites, most prominently in all smooth muscles and in basement membranes of lung and kidney. Cytotactin appears in adult tissues with distributions that are similar to those seen in embryonic tissues. The findings raise the possibility that certain ECM proteins contribute to pattern formation in embryogenesis as a result of their restricted expression in a spatiotemporally regulated fashion at some sites but not at others.
Individual neurons can express both the neural cell adhesion molecule (N-CAM) and the neuron-glia cell adhesion molecule (Ng-CAM) at their cell surfaces. To determine how the functions of the two molecules may be differentially controlled, we have used specific antibodies to each cell adhesion molecule (CAM) to perturb its function, first in brain membrane vesicle aggregation and then in tissue culture assays testing the fasciculation of neurite outgrowths from cultured dorsal root ganglia, the migration of granule cells in cerebellar explants, and the formation of histological layers in the developing retina. Our strategy was initially to delineate further the binding mechanisms for each CAM. Antibodies to Ng-CAM and N-CAM each inhibited brain membrane vesicle aggregation but the binding mechanisms of the two CAMs differed. As expected from the known homophilic binding mechanism of N-CAM, anti-N-CAM-coated vesicles did not co-aggregate with uncoated vesicles. Anti-Ng-CAM-coated vesicles readily co-aggregated with uncoated vesicles in accord with a postulated heterophilic binding mechanism. It was also shown that N-CAM was not a ligand for Ng-CAM. In contrast to assays with brain membrane vesicles, cellular systems can reveal functional differences for each CAM reflecting its relative amount (prevalence modulation) and location (polarity modulation). Consistent with this, each of the three cellular processes examined in vitro was preferentially inhibited only by anti-N-CAM or by anti-Ng-CAM antibodies. Both neurite fasciculation and the migration of cerebellar granule cells were preferentially inhibited by anti-Ng-CAM antibodies. Anti-N-CAM antibodies inhibited the formation of histological layers in the retina. The data on perturbation by antibodies were correlated with the relative levels of expression of Ng-CAM and N-CAM in each of these different neural regions. Quantitative immunoblotting experiments indicated that the relative Ng-CAM/N-CAM ratios in comparable extracts of brain, dorsal root ganglia, and retina were respectively 0.32, 0.81, and 0.04. During culture of dorsal root ganglia in the presence of nerve growth factor, the Ng-CAM/N-CAM ratio rose to 4.95 in neurite outgrowths and 1.99 in the ganglion proper, reflecting both polarity and prevalence modulation. These results suggest that the relative ability of anti-Ng-CAM and anti-N-CAM antibodies to inhibit cell-cell interactions in different neural tissues is strongly correlated with the local Ng-CAM/N-CAM ratio.(ABSTRACT TRUNCATED AT 400 WORDS)
In order to properly evaluate results after reduction mammaplasty and correction of breast asymmetry, it is necessary to follow patients for several years. Cases are presented in which unusual deformities occurred after an initial satisfactory result. Pregnancy, aging, and fluctuations in weight contributed to these deformities. A case of recurrent hypertrophy 4 years following a reduction mammaplasty is presented. Several cases of asymmetry corrected by a combination of reduction and augmentation had early satisfactory results but several years later again showed asymmetry due to recurrent ptosis or atrophy. In one case, a 10-year follow-up showed considerable deformity after an initial good result following asymmetrical augmentation. It is important to point out to patients that changes do occur and that occasionally additional surgery is necessary.
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The signs and symptoms of reactive hypoglycemia mimic the manifestations of other clinical disorders. The oral glucose tolerance test (OGTT) is a widely accepted diagnostic procedure to evaluate patients suspected of having reactive hypoglycemia. The reproducibility of the OGTT has not been previously assessed in a large group of patients. We evaluated the consistency of glucose nadirs at 50 mg/dl and below during two consecutive OGTTs for diagnostic screening of 59 patients with postprandial symptoms of hypoglycemia. The mean nadirs of the consecutive OGTTs were 56 +/- 12 mg and 57 +/- 13 mg, both significantly below the mean nadir of asymptomatic subjects (P less than .001). The nadir of the first OGTT was at or below 50 mg/dl in a subgroup of 20 patients ("hypoglycemic"). On the repeat OGTT, 13 previously "hypoglycemic" patients had nadirs over 50 mg/dl on the second OGTT. Nine of the 39 remaining patients had nadirs below or equal to 50 mg/dl during their second OGTT. Thus, 37% of all patients had a change in diagnostic classification in the second OGTT based on the glucose nadir level. We conclude that the glucose nadir during OGTT is an inconsistent and unreliable screening criterion for evaluating patients with recurrent postprandial hypoglycemic symptoms in clinical practice.
A new impedance plethymograph respiratory monitor, (AR-8800), was tested on anaesthetised dogs. Decreases in tidal volume and total apnoea were brought about by partial and complete airway obstruction and by partial and total muscle paralysis. The changes in respiration were reliably detected by the monitor and its alarms activated within 15-20 seconds. The misinterpretation of gross body movement as normal breathing did not occur. Our findings suggest that the AR-8800 is a safe and dependable monitor which has distinct advantages and may be of particular use in the monitoring of patients at risk of developing respiratory depression or obstruction, whether in the intensive care unit, the general ward or at home.
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A case of tuberculous flexor tenosynovitis causing a carpal tunnel syndrome is described. Surgery initially relieved the patient's symptoms, but the disease process continued until the diagnosis was made and appropriate treatment was instituted. This diagnosis, although rare, should be considered as the etiology in a carpal tunnel syndrome, particularly when there is evidence of a proliferative tenosynovitis and radiographs show diffuse osteoporosis.
We present 3 cases of iatrogenic phallic denudation that were managed successfully nonoperatively. The concept of conservative, nonoperative management should be considered in denudation injuries.
An extracellular matrix protein, cytotactin, with widespread tissue distribution has been identified, isolated, and partially characterized. Cytotactin mediates glia-neuron adhesion in vitro, but unlike Ng-CAM, the neuron-glia cell-adhesion molecule, it is absent from neurons. Cytotactin was isolated from 14-day embryonic chicken brains as structurally related polypeptides of Mr 220,000, 200,000, and 190,000. These polypeptides were efficiently extracted in the absence of detergent and appeared to be disulfide-linked into higher polymers. Immunofluorescence staining with specific antibodies indicated that cytotactin is found in extracellular spaces and in basement membranes of a variety of non-neural tissues including smooth muscle, lung, and kidney. In the cerebellum, it appears on glial end-feet, on Bergmann glial fibers, and in extracellular spaces. The molecule is synthesized by glia and cells from smooth muscle, lung, and kidney. It is found at the surface of glia in culture in a cell-associated fibrillar pattern. A survey of the times and sites of its appearance during embryogenesis is consistent with the hypothesis that cytotactin is a cell-substrate adhesion molecule that may mediate cell migration in a site-restricted fashion.
A male patient was admitted to the hospital in coma and acute respiratory failure following the oral intake of benzodiazepines and alcohol. On the fourth day after admission, the patient was conscious, results of clinical examination of the respiratory system were normal, and pulmonary ventilation tests and blood gas measurements were within normal limits. However, mouth occlusion pressure and ventilatory response to CO2 were found to be markedly reduced. In the period of weaning the discrepancy between the normal clinical picture and blood gases and the laboratory findings of respiratory depression implies that there is a slowing in recovery of the respiratory center in this type of intoxication.
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We report a case in which repair of a cleft of the secondary palate subsequently separated. A pharyngeal flap failed to provide capability for velopharyngeal closure and required revision. The revision was not successful because of scar contracture obstruction of the lateral ports by tonsillar tissue. The problem of scar contracture was eventually solved with a specially constructed prosthesis. The management of each of these complications is discussed.
Embryonic chicken brain tissue cultured in media containing 35S-labeled sulfate or 32P-labeled phosphate incorporated 35S or 32P into the neural cell adhesion molecule (N-CAM). The 35S label was located in asparagine-linked carbohydrates on both glycopeptides (molecular weights, 170,000 and 140,000) but not in the sialic acid. The 32P label was detected in phosphoamino acids in the carboxyl-terminal third of both polypeptides, but the ratio of phosphoserine to phosphothreonine differed in the two species. The sulfated saccharides and phosphoamino acids may provide additional sites for functional control of N-CAM.