Biomedical subjects
Publications and source records attributed to E Thomas.
Diminutive polyps found on flexible sigmoidoscopy are predominantly hyperplastic, but it is impossible to rely on endoscopic appearance to make an accurate diagnosis. Colonoscopy, polypectomy, and full pathologic evaluation are recommended for all such polyps. Follow-up care varies depending on the nature of the lesion.
A computational model of the flow of activity in a vertically organized slab of cat primary visual cortex (area 17) has been developed. The membrane potential of each cell in the model, as a function of time, is given by the solution of a system of first order, coupled, non-linear differential equations. When firing threshold is exceeded, an action potential waveform is "pasted" in. The behavior of the model following a brief simulated stimulus to afferents from the dorsal lateral geniculate nucleus (dLGN) is explored. Excitatory and inhibitory post-synaptic potential (E and IPSP) latencies, as a function of cortical depth, were generated by the model. These data were compared with the experimental literature. In general, good agreement was found for EPSPs. Many disynaptic inhibitory inputs were found to be "masked" by the firing of action potentials in the model. To our knowledge this phenomenon has not been reported in the experimental literature. The model demonstrates that whether a cell exhibits disynaptic or polysynaptic PSP latencies is not a fixed consequence of anatomical connectivity, but rather, can be influenced by connection strengths, and may be influenced by the ongoing pattern of activity in the cortex.
Clinical, histopathological, and ultrastructural features of an extended intracranial malignant neoplasm are presented. Following incomplete extirpation of a large epidural tumor at the temporal base of the skull, the 21-year-old male patient suffered from several local recurrences and died at the age of 27. The neoplasm was defined by its histopathological and ultrastructural characteristics and by the pattern of its antigenicity as a malignant rhabdoid tumor (MRT). Considering previous publications on MRT, this case may be the first of primary intracranial MRT appearing in an adult.
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A case of pneumonia and acute tubular necrosis was caused by an initially unknown species of Legionella. The organism was later identified as Legionella maceachernii by a combination of cultural, biochemical, and serological methods along with a gas-liquid chromatographic profile.
The clinical effects of high-volume spinal anaesthesia with bupivacaine 0.125% were studied in 30 patients presenting for postpartum sterilisation. Group A, B and C patients received 6, 8 and 10 ml of bupivacaine 0.125% respectively. Onset, duration and regression of sensory block and motor blockade, haemodynamic parameters and postoperative complications were studied. A sensory level of T10 was reliably obtained in Group B and C but not in Group A. Similarly motor blockade was unreliable in Group A compared with Group B (P < 0.05) and Group C (P < 0.05). Two segment regression times were similar in all three groups. L1 regression times were 47.9, 94.3 and 99.0 minutes in Groups A, B and C respectively. The corresponding times for complete recovery of motor power were 120, 212.3 and 182.7 minutes respectively (P < 0.01 when Group A compared to B and C). A significant incidence of high spinal anaesthesia occurred when 10 ml bupivacaine 0.125% was administered (P < 0.05 when compared with Group A). No patient experienced respiratory discomfort in spite of sensory levels of up to T1. Hypotension responded readily to intravenous fluids and small doses of ephedrine (three patients). Only one patient (Group A) developed a postdural puncture headache. In this study, high-volume spinal anaesthesia with bupivacaine 0.125% was found to be satisfactory for postpartum tubal ligation. The optimal volume of bupivacaine 0.125% was 8 ml.
This paper presents experiences encountered with protein-modified diets (PMD) in the management of 67 patients, aged 1 day to 14 years, followed in the Pediatric Nutrition Clinic in the past 5 years. All had inborn errors of amino acid metabolism: maple syrup urine disease (MSUD), 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) lyase deficiency, propionic acidemia (PPA), or methylmalonic aciduria (MMA). In early infancy, the diet prescription is frequently adjusted to search for the infant's tolerance level of restricted amino acids. The levels must be established when natural foods other than milk are added to the PMD. The amino acids restricted are leucine, isoleucine, and valine in MSUD; leucine in HMG-CoA lyase deficiency; and isoleucine, methionine, threonine, and valine in PPA and MMA. Efficacy of the PMD depends on accuracy in prediction of the restricted amino acid requirement and the willingness and ability of parents and patients to conform to its demands.
Early studies confirmed the beneficial effects of calcium channel blockers on the normal oesophagus, which included a decrease in lower oesophageal sphincter tone in achalasia and a decrease in oesophageal contractions and amplitude in diffuse oesophageal spasm. This resulted in the enthusiastic use of the drugs in both disorders. With further experience, and with increased recognition of side effects, the role of these drugs in the 2 disorders has been better clarified. Clinical trials in general have not reflected the improvement observed in the manometric parameters. Only a minority of patients appear to derive sustained symptomatic benefit. Calcium channel blockers may be the initial choice for high or moderate risk patients with achalasia prior to proceeding with pneumatic dilatation or surgical myotomy. In diffuse oesophageal spasm, they are a reasonable first choice for all risk categories.
Uniparental disomy has recently been recognized to cause human disorders, including Prader-Willi syndrome (PWS). We describe a particularly instructive case which raises important issues concerning the mechanisms producing uniparental disomy and whose evaluation provides evidence that trisomy may precede uniparental disomy in a fetus. Chorionic villus sampling performed for advanced maternal age revealed trisomy 15 in all direct and cultured cells, though the fetus appeared normal. Chromosome analysis of amniocytes obtained at 15 wk was normal in over 100 cells studied. The child was hypotonic at birth, and high-resolution banding failed to reveal the deletion of 15q11-13, a deletion which is found in 50%-70% of patients with PWS. Over time, typical features of PWS developed. Molecular genetic analysis using probes for chromosome 15 revealed maternal disomy. Maternal nondisjunction with fertilization of a disomic egg by a normal sperm, followed by loss of the paternal 15, is a likely cause of confined placental mosaicism and uniparental disomy in this case of PWS, and advanced maternal age may be a predisposing factor.
An 8-year-old boy with perinatal HIV infection developed a large fusiform aneurysm in the circle of Willis two years prior to death which was confirmed by radiological studies. The postmortem examinations revealed a predominantly intimal, proliferative lesion, and partial destruction of the internal elastic lamina in the involved arteries. Within the intima hyperplasia of fibroblasts and smooth muscle cells was observed. No inflammatory alterations, no granulomas and no multinucleated giant cells could be noted in the vascular walls and in the cerebral parenchyma. A small ischemic infarct was present in the left thalamus. Cerebellum, brainstem and medulla showed multiple areas of progressive multifocal leukoencephalopathy (PML). Immunohistochemistry with anti-gp41, a monoclonal antibody against HIV envelope did not exhibit any positive results. These findings implicate that the vascular lesion might be attributed to primary infection of the brain by HIV which led to a defect of elastic lamina and consecutive intimal hyperplasia. A second hypothesis could be based on the effect of extremely high dose AZT therapy avoiding inflammatory reaction after HIV infection.
Most people suffering from migraine present a hypersensitivity of the cervico-facial muscles, which may be linked to magnesium deficit. This paper describes a comparative study of serum and erythrocyte magnesium levels in 79 migraine patients and 55 controls. Serum magnesium did not differ significantly in either group, but some values were quite low. On the other hand, there was a significantly greater erythrocyte magnesium deficit in persons suffering from migraine than in controls (in both female and male subjects). This fact correlates with the improved state of migraine patients (already ascertained in earlier studies) following treatment consisting of the intake of magnesium-rich water. The findings support the hypothesis of a magnesium deficit in people suffering from migraine and raise the problem of the relationship between migraine and other pathologies, including chronic magnesium deficit, latent tetany due to magnesium deficit, mitral valve prolapse, and allergy.
Difficult intubation has been much discussed in the anaesthetic literature. The incidence of difficult intubation (11:560) was higher in obstetric patients (6:277) as compared to gynaecological patients (5:283) in our hospital. We tested the Mallampati's classification as a predictor of difficult intubation in 277 obstetric and 283 gynaecological patients. We recommend that Mallampati's classification can be used reliably (p less than 0.05) to predict difficult intubation in obstetric but not in gynaecological patients.
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The importance of papillitis as a disease entity capable of producing significant symptoms is not well appreciated. Presenting symptoms are usually pain or cholestasis. The cholangiographic appearance of papillitis may mimic that of papillary tumor and small distal common bile duct stone; endoscopic papillotomy (EPT) with biopsy may help clarify the diagnosis. In patients with delayed drainage, EPT may be therapeutic. Two cases of papillitis that presented as difficult diagnostic and therapeutic problems are reported.
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A low buoyant density fraction (A4) was isolated from human cartilage by CsCl density gradient ultracentrifugation. This fraction contained a hydrodynamically small proteoglycan (Kav, 0.74 on Sepharose CL-2B) that reacted with monoclonal antibody 12/20/1C6 specific for the hyaluronic acid binding region (G1 globe) of the large aggregating high-density proteoglycan isolated from many animal cartilages. Despite the presence of the hyaluronic acid binding region, this small proteoglycan did not form proteoglycan aggregates with hyaluronan, not even in the presence of link protein.
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