Search PubMed⌕ Search

Biomedical subjects

C Lazarus

Publications and source records attributed to C Lazarus.

At least 37 records · Page 2Linked to original sources
PubMed1999

Modulation of 5-hydroxytryptamine release in hippocampal slices of rats: effects of fimbria-fornix lesions on 5-HT1B-autoreceptor and alpha2-heteroreceptor function.

Fimbria-fornix lesions disrupt important parts of serotonergic and noradrenergic hippocampal afferents and elicit sprouting of sympathetic fibers from the superior cervical ganglion. Since 5-hydroxytryptamine (5-HT) release in the hippocampus is modulated by 5-HT1B auto- and alpha2-heteroreceptors, we investigated whether such lesions may alter these presynaptic mechanisms. Hippocampal slices of sham-operated (SHAM) and fimbria-fornix-lesioned (LES) rats (14 months after surgery) were preincubated with [3H]5-HT, superfused continuously, and stimulated electrically using two stimulation conditions: either (a) 360 pulses 3 Hz, or (b) 20 pulses 100 Hz (2 ms, 28 mA, 4 V/chamber). The amount of [3H]5-HT taken up by slices from LES rats was significantly reduced, whereas the evoked 5-HT release (in percent of tissue-3H) was unchanged compared to that of SHAM rats. The 5-HT1B agonist CP 93,129 or the alpha2-agonist UK 14,304 reduced the evoked 5-HT release more potently in slices from LES rats, but only using stimulation condition (a), which permits inhibition by endogenously released transmitters. In LES rats, the facilitatory effect of the 5-HT antagonist metitepine was weaker, whereas that of the alpha2-antagonist idazoxane was more pronounced than in SHAM rats. In LES rats, hippocampal 5-HT content was reduced to about 45% of SHAM levels, whereas that of noradrenaline was increased by about 30% (high-performance liquid chromatography). We conclude: (1) despite LES-induced changes in tissue levels of endogenous ligands, there is no down- or upregulation of 5-HT1B-autoreceptors or alpha2-heteroreceptors on serotonergic neurons in the denervated rat hippocampus. (2) The reduced endogenous autoinhibition (by 5-HT) seems to be compensated for by an increased heteroinhibition (by noradrenaline).

Adrenergic alpha-Agonists↗
PubMed1998

Biosynthesis of C18 polyunsaturated fatty acids in microsomal membrane preparations from the filamentous fungus Mucor circinelloides.

The biosynthesis of C18 polyunsaturated fatty acids has been studied in the fungus Mucor circinelloides. Microsomal membrane preparations contained delta9, delta12 and delta6 desaturase activities. The delta9 desaturase exhibited characteristics similar to those of the animal and yeast delta9 desaturases in being membrane bound and utilising stearoyl-CoA as substrate. Cytochrome b5 (a soluble form lacking the 20-amino-acid hydrophobic C-terminus) stimulated desaturation and was identified as a major cytochrome component of the membranes. A high ferricyanide reductase activity (indicative of NADH:cytochrome b5 reductase activity) coupled to inhibition by cyanide further supported the similarity with the mammalian and yeast enzymes. Time-course studies with radiolabelled oleoyl-CoA showed that the oleate [18:1(9)] was transferred to position sn-2 of phosphatidylcholine (PtdCho) and was desaturated to linoleoyl-PtdCho. Removal of the excess oleoyl-CoA from the membranes prior to addition of reductant confirmed that oleoyl-PtdCho is a substrate for the delta12 desaturase. The entry of oleate at this position of the phospholipid was facilitated by the activity of lyso-PtdCho:acyl-CoA acyltransferase (LPCAT), which readily transferred oleate from oleoyl-CoA to lyso-PtdCho. Desaturation of oleate at the sn-1 position of PtdCho was also demonstrated after the entry of oleate in to the phospholipid by the enzymes of the Kennedy pathway. Thus oleate at sn-1 and sn-2 positions served as substrate for the delta12 desaturase and is consistent with observations in oil seed tissues. LPCAT activity was substantially higher than that observed with lysophosphatidylethanolamine:acyl-CoA acyltransferase (LPEAT) indicating that oleate is less effectively channelled to phosphatidylethanolamine for linoleate synthesis. No desaturation on phosphatidylinositol could be demonstrated. Delta6 desaturase utilised linoleate at the sn-2 position of exogenously supplied PtdCho presented to the membranes in the presence of reductant. Thus, the entry of substrates into PtdCho via LPCAT and the synthesis of linoleate [18:2(9,12)] and gamma-linolenate [18:3(6,9,12)] on this phospholipid is similar to that reported for oil seed membranes.

Acyl Coenzyme A↗
PubMed1998

Hypothyroldism in a neonate following excision of a cervical teratoma.

Hypothyroidism developed in a neonate following the excision of a large cervical teratoma. This finding supports the observation that cervical teratomas commonly arise from thyroid tissue. Thyroid function tests should be performed routinely in all patients in whom identifiable residual thyroid tissue is not demonstrated at the conclusion of the operation.

Female↗
PubMed1995

Effects of a sour bolus on oropharyngeal swallowing measures in patients with neurogenic dysphagia.

This study examines the effects of a sour bolus (50% lemon juice, 50% barium liquid) on pharyngeal swallow measures in two groups of patients with neurogenic dysphagia. Group 1 consisted of 19 patients who had suffered at least one stroke. Group 2 consisted of 8 patients with dysphagia related to other neurogenic etiologies. All patients were selected because they exhibited delays in the onset of the oral swallow and delays in triggering the pharyngeal swallow on boluses of 1 ml and 3 ml liquid barium during videofluoroscopy. Results showed significant improvement in oral onset of the swallow in both groups of patients and a significant reduction in pharyngeal swallow delay in Group 1 patients and in frequency of aspiration in Group 2 patients with the sour as compared to the non-sour boluses. Other selected swallow measures in both subject groups also improved with the sour bolus. Volume effects were present but not as consistently as in prior studies. Implications for swallow therapy are discussed.

Adult↗
PubMed1995

Acute appendicitis among black South Africans.

Acute appendicitis has become the commonest nontrauma-related abdominal surgical emergency at Cecilia Makiwane Hospital. The records of 122 patients undergoing appendicectomy were reviewed. Attention is drawn to late presentation and the high complication rare encountered. Mortality rate (0.8%) and overall diagnostic accuracy (85%) were acceptable. The need for adequate patient education is stressed as a possible measure to reduce high morbidity associated with late presentation.

Acute Disease↗
PubMed1994

Hippocampal amino acid concentrations after raphe and/or septal cell suspension grafts in rats with fimbria-fornix lesions.

Two weeks after infracallosal electrolytic fimbria-fornix lesions, Long-Evans female rats received intrahippocampal suspension grafts of either fetal septal or mesencephalic raphe tissue, or a mixture of both. Ten months after lesion surgery, the concentrations of alanine, aspartate, GABA, glutamate, glutamine, glycine, serine and taurine were determined in a dorsal, a "middle" and a ventral region of the hippocampus. We found neither the lesions nor the grafts to have significantly modified the concentration of these amino acids which, in all groups, presented a regional heterogeneity in their hippocampal distribution. GABA, glutamate and glutamine were highest in the ventral hippocampus, whereas the other amino acids were highest in the dorsal region. Our results (i) show that fimbria-fornix lesions do not result in lasting effects on hippocampal concentrations of the assessed amino acids, (ii) confirm the regional heterogeneity in the distribution of these amino acids in the hippocampus and (iii) demonstrate that cell suspension grafts of fetal septal or mesencephalic raphe tissue, as well as grafts of a mixture of both of these tissues, do not exert a non-specific effect on either of the amino acid concentrations measured. These data complete those of the preceeding paper [Kiss et al. (1990) Neuroscience 36, 61-72] concerning the effects of the same grafts on hippocampal cholinergic, serotonergic and noradrenergic markers, as well as on several behavioural variables.

Amino Acids↗
PubMed1994

The value of abrasive cytology in the early detection of oesophageal carcinoma. A pilot survey in Ciskei.

The use of abrasive cytology as a screening procedure in the diagnosis of early cancer of the oesophagus among asymptomatic rural Ciskeians was assessed. An inexpensive, locally manufactured brush biopsy capsule was used to obtain cytological material from 1,336 subjects. The technique gives a high yield, has a high predictive value and identifies a high prevalence of sufferers at the detectable preclinical phase of the disease.

Carcinoma, Squamous Cell↗
PubMed1993

Comparison of simultaneous 99mTc-HMPAO and 111In oxine labelled white cell scans in the assessment of inflammatory bowel disease.

Forty-seven patients, 29 with chronic inflammatory bowel disease (IBD) and 18 with presumed irritable bowel syndrome, including one with uncomplicated diverticular disease, were studied with simultaneous technetium-99m hexamethylpropylene amine oxime and indium-111 oxine labelled leucocyte scans performed at 1, 3 and 24 h. Twenty-seven patients with IBD had active disease as judged by clinical and laboratory criteria and all of these had positive scans with both agents. No false positive studies were obtained. The 1-h 99mTc-HMPAO WBC scans showed the same distribution to disease as the 3-h 111-In WBC scans, with no difference in intensity (P < 0.92); they showed more extensive disease (P < 0.02) and more intense uptake (P < 0.001) than did the 1-h 111-In scans. The 3-h 99mTc-HMPAO WBC scans showed more extensive disease (P < 0.002), with greater intensity (P < 0.0005), than did the 3-h 111In WBC scans. Physiological bowel activity on 3-h 99mTc-HMPAO WBC scans was present in 12 patients but was faint and did not interfere with assessment of disease extent and activity. It is concluded that in terms of isotope availability, radiation dosimetry and image quality, 99mTc-HMPAO is the agent of choice in detecting active IBD, with localization of disease possible at 1-h after re-injection and optimal resolution and definition of disease extent at 3 h. A negative scan reliably excludes active disease.

Adult↗
PubMed1992

Impact of the diagnostic procedure on outcome measures of swallowing rehabilitation in head and neck cancer patients.

This study was designed to determine whether swallow rehabilitation outcomes were affected by the type of evaluation procedure utilized by the clinician. The two evaluation techniques compared were the bedside examination and videofluoroscopy (the modified barium swallow). Ten institutions participated in this study, enrolling a total of 103 partial laryngectomized patients, 21 in the bedside arm and 82 in the videofluoroscopy arm. Data on recovery of oral intake were collected weekly. All patients received an X-ray study of swallow at 3 months after the operation. Mean time to oral intake of food was significantly lower in patients assessed with bedside examination. Overall swallow measures of transit times and swallow efficiencies after 3 months revealed significantly better function in the videofluoroscopy group. Results are discussed in terms of the visibility of swallow physiology with the two assessment techniques, the accuracy of therapy planning with the bedside examination versus videofluoroscopy and the ability of head and neck cancer patients to tolerate some aspiration without developing aspiration pneumonia.

Deglutition↗
PubMed1992

Brush cytology technique in the detection of oesophageal carcinoma in the asymptomatic, high risk subject; a pilot survey.

This study assesses the reliability of abrasive brush cytology in the diagnosis of early cancer of the oesophagus among asymptomatic rural Ciskeians. An inexpensive locally manufactured brush biopsy capsule was used to obtain cytological material from 1336 subjects; 59% of them were brushed a second time. The technique appears to have a high sensitivity (90%) and specificity (99.9%). Three of five asymptomatic subjects diagnosed as having early oesophageal cancer refused further treatment, indicating the importance of health education as a prerequisite to the introduction of a screening programme for oesophageal cancer.

Adult↗
PubMed1991

Interactions of testosterone with the olfactory system in the display of mounting behavior in the female rat.

Adult ovariectomized female rats received a testosterone propionate (TP) silastic implant (day 0) and were subsequently tested for mounting behavior. The number of females displaying mounting behavior increased from day 2 (0%) to day 14 (94%) following testosterone implantation. Olfactory bulbectomy (OB) performed on day -7 or on day +14 reduced the number of females that mounted on day +16 as compared to sham counterparts. However, the number of females displaying mounting behavior was significantly higher when OB was performed on day +14 than on day -7. Peripheral anosmia induced by ZnSO4 instillation, either with multiple instillations beginning on day -8 before TP implant or with a single injection on day +14, equally impaired mounting behavior on day +16. These results, which further confirm the role of the olfactory system in facilitating the display of mounting behavior in the female rat, suggest an olfaction-testosterone interaction.

Animals↗
PubMed1989

Experience in imaging medullary thyroid carcinoma using 99mTc (V) dimercaptosuccinic acid (DMSA).

99mTc (V) dimercaptosuccinic acid (DMSA) is a new tumor imaging agent that has been successfully used to image patients with medullary thyroid carcinoma (MTC). Since 1986, studies have been performed in 32 patients with histologically proven MTC at Guy's Hospital, London, England. Five patients with primary tumor were studied prior to surgery, four patients were studied after successful removal of the primary tumor, and 26 patients with biochemical evidence of recurrence were studied. Eight patients were studied serially to assess progression of disease, and four patients were studied before and after surgery. Twenty-one of the 26 patients with disease had positive scans with four false-negative scans and three true negative scans. One patient had a false-positive scan (sensitivity 80%, specificity 75%). Two of the false-negative scans were obtained in patients with moderate but stable elevations of calcitonin but no other evidence of recurrence. One false-negative scan was obtained in a patient who was discovered on screening to have an abnormal pentagastrin response, and a small 1 cm tumor was subsequently removed. Uptake in local neck recurrence was frequently intense, but uptake at sites of bone metastases was less marked. 99mTc (V) DMSA is an inexpensive radiopharmaceutical which produces good quality images and has been shown to have an acceptable sensitivity and specificity in the follow-up of patients with MTC and thereby contributes significantly to the management of these patients.

Adolescent↗
PubMed1987

Pott's paraplegia.

Experience gained in the management of 261 patients with tuberculous paraplegia and paraparesis seen over a 17-year period is presented. A plea is made for prompt spinal canal decompression in all cases of tuberculosis of the spine with evidence of neurological involvement.

Adolescent↗