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Biomedical subjects

J Barron

Publications and source records attributed to J Barron.

At least 55 records · Page 3Linked to original sources
PubMed1982

Syndrome of inappropriate antidiuretic hormone secretion following dis-dichlorodiammineplatinum II in a patient with malignant thymoma.

A patient with malignant thymoma is reported, in whom the syndrome of inappropriate antidiuretic hormone secretion (SIADH) occurred 36-48 hours after being given cis-Dichlorodiammineplatinum II (CPPD) with a mannitol diuresis. The SIADH was treated by fluid restriction and demeclocycline and subsided after approximately 72 hours. Subsequent courses of CPPD with mannitol diuresis were given with demeclocycline prophylactically and no untoward effects noted. The precise mechanism for the SIADH following the use of CPPD is unknown, but may be life-threatening, especially since preloading with fluid followed by forced diuresis is used when CPPD is given to avoid nephrotoxicity. The patient has survived 37 months, with 24 months of relapse-free survival following treatment with CPPD, irradiation and surgery.

Cisplatin↗
PubMed1982

The enigma of microtubule coils in brain synaptosomes.

When synaptosomes are prepared from rat brain and incubated in Krebs solution, the presynaptic bulb develops a coil of microtubules (mts). Various considerations indicate that the coil does not have a cytoskeletal supportive function. Synaptosome coil mts show certain peculiarities, e.g. they thrive during incubation in Krebs solution (dendritic mts are depolymerized in Krebs solution) and they show no protofilament molecular substructure with tannic acid. Dendritic mts show clearly a 13 protofilament substructure when processed in the same way. Synaptosomal coil mts are sensitive to micromolar calcium and are depolymerized by treatment of the synaptosomes with veratridine or A23187. Our evidence indicates that coil mts of synaptosome and synaptic vesicle clothed mts of 'intact' albumin-treated synapses are different morphological and functional entities. As mentioned above, the function of coil mts remains enigmatic, while the mts seen in albumin-treated synapses could well have a role in synaptic vesicle translocation.

Animals↗
PubMed1982

Dissection of stages in exocytosis in the adrenal chromaffin cell with use of trifluoperazine.

Stimulation of isolated chromaffin cells with carbamylcholine led to a number of morphological changes, indicative of exocytosis, apparently resulting from translocation of secretory granules to the plasma membrane and their subsequent fusion with the plasma membrane to release their contents. However, stimulation in the presence of trifluoperazine resulted only in the accumulation of secretory granules close to the plasma membrane. Thus exocytosis could be divided into two stages: a trifluoperazine-insensitive stage involving translocation of secretory granules to the plasma membrane and a second trifluoperazine-sensitive stage resulting in granule-plasma membrane fusion.

Adrenal Medulla↗
PubMed1982

Depolymerization of dendritic microtubules following incubation of cortical slices.

Electron microscopical examination indicated that incubation of slices of rat cerebral cortex in Krebs buffer at room temperature of 37 degrees C led to a rapid and more or less complete depolymerization of dendritic microtubules. The loss of dendritic microtubules did not appear to be a consequence of anoxia. Myelinated axons showed only a partial loss of microtubules and the microtubules of preterminal axons were unaffected by incubation. These results indicate differential labilities of axonal and dendritic microtubules under these conditions of incubation. Such an effect of the incubation of slices in Krebs buffer indicates a need for caution in the interpretation of experiments on slice preparations.

Animals↗
PubMed1982

Synaptic organisation and neuron microtubule distribution.

The microtubules in different parts of the neuron and synaptosomes were examined with respect to their stability, structure and orientation. On the basis of distribution, different labilities and differences in protofilament substructure seen by tannic acid staining, we have classified microtubules into eight major categories. Functional involvements in vesicle translocation, cytoskeletal support and the regulation of assembly/disassembly are considered.

Animals↗
PubMed1982

Somatostatin-28 inhibits LHRH-stimulated gonadotrophin secretion in man.

The LH and FSH responses to 100 micrograms LHRH in a combined pituitary stimulation test were compared to five normal men during infusions of somatostatin-28 (SS-28) and somatostatin (SS-14) and during control infusions of haemacel. SS-28 and SS-14 were administered in equimolar concentrations of 1.8 nmol/kg body weight over 210 min and LHRH was injected as a bolus at 120 min after commencement of the infusion. SS-28 significantly reduced both LH and FSH responses to LHRH compared with control infusions. SS-14 did not significantly alter the FSH response but caused a significant reduction in the LH concentration 75 and 90 min after LHRH injection. These findings demonstrate that SS-28 has distinct biological activity in addition to its role as a putative precursor of SS-14. Inhibition of gonadotropin hormone secretion by SS-14 and SS-28 suggest that these hypothalamic peptides may play a part in the regulation of LH and FSH secretion.

Adult↗
PubMed1982

Cloacogenic carcinoma: a study of six cases and review of literature.

A clinicopathological study of six cases of cloacogenic carcinoma and review of the literature was undertaken. These tumors arise from transitional epithelium of the pectinate line. The tumors are often deceptive in the beginning and may often resemble small abscesses, fissures, or fistulas. Often they appear outside the mucosa and skin. Histologically, they are well, moderately, or poorly differentiated. Local excision is adequate for small noninfiltrating tumors. Pelvic radiation, combined with surgery for lesions greater than 2 cm with local extension and/or pelvic nodes, controls the pelvic disease. Well and moderately differentiated tumors have a better prognosis than squamous cell carcinoma. Overall survival rate is approximately 50%. Cure rate depends on the size of the lesion, differentiation of tumor, depth of invasion, duration of the symptoms, nodal involvement, lymphatic or vascular invasion, and contiguous organ invasion. Cloacogenic carcinoma is a better term than other names used in the literature for this tumor.

Aged↗
PubMed1981

Vaginal evisceration. A case report and brief review of the literature.

A 70-year-old woman was successfully treated for spontaneous vaginal evisceration, with extensive infarction of small intestine, by an abdominal and vaginal approach. Vaginal evisceration is a rare condition. It usually occurs in postmenopausal women after one or more vaginal operations and in the presence of an enterocele or other local abnormalities that contribute to tissue weakness. Prompt recognition and surgical treatment, combining abdominal and vaginal approaches as indicated, and use of ancillary antibiotics and anticoagulant regimens is associated with successful outcome in most instances.

Aged↗
PubMed1981

Angiodysplasia of the right colon treated by embolization with ivalon (polyvinyl alcohol).

Angiodysplasia of the colon is being recognized with increasing frequency as a source of lower gastrointestinal bleeding in the elderly. In one patient with colonic angiodysplasia, superselective segmental embolization of the ileo-colic artery with Ivalon resulted in the cessation of bleeding without causing bowel infarction. However, because of the development of collateral branches to the angiodysplastic malformation, bleeding recurred. While colectomy remains the treatment of choice in younger patients, in high risk patients embolization with a permanent embolic material, such as Ivalon, is an attractive alternative.

Aged↗
PubMed1980

Microtubules, dendritic spines and spine appratuses.

Using techniques for enhanced microtubular preservation, including albumin pretreatment (Gray, 1975), occipital cortex of rats was studied electron microscopically at various ages of development. A close structural relationship was seen between microtubules, sacs of SER and the postsynaptic "thickening" in primordial spines and with the dense "plate" material of spine apparatuses. Stereoscopic preparations in addition show a more complicated substructure than previously described for the "plate". Microtubules may contribute to the formation of the "plate" of the spine apparatus which in turn is associated with the postsynaptic "thickening" of the mature spine. Possible functional correlates are discussed.

Aging↗
PubMed1980

Cold stable microtubules in brain studied in fractions and slices.

Microtubules were shown to remain intact in brain slices and subfractions maintained at 0 degrees C for 1 h. Under the same conditions, microtubules isolated from brain by warm assembly-cold disassembly methods, disassemble into their constituent subunit proteins. No selective depletions of microtubules were seen when brain slices were incubated in homogenizing buffer at either 0 degrees C or 37 degrees C. The response of native microtubules in brain slices in incubation in other solutions showed that their properties were otherwise the same as those of assembled microtubules. The separated alpha and beta subunits of isolated cold labile and cold stable microtubules were compared by electrophoresis and isoelectric focusing and were shown to possess the same mobilities. The results suggest that native microtubules are temperature insensitive and that isolated microtubules are assembled from pre-existing pools of subunit proteins. The results further suggest that native microtubules possess a factor, lacking in isolated assembled microtubules, which confers temperature stability on the former.

Animals↗
PubMed1979

Aggregations of synaptic vesicles on the exposed inner membrane of presynaptic mitochondria in brain.

Fragments of rat cerebral cortex have been incubated under various conditions. When divalent cations are present, patches of the external membrane of some mitochondria are disassembled leaving the inner mitochondrial membrane exposed to the cytoplasm. Sometimes the entire external membrane is missing. In presynaptic bulbs the synaptic vesicles are attracted and adhere to the exposed outer face of the inner mitochondrial membrane. The mode of attraction and adhesion of the vesicles is discussed. Possibly this could serve as a model for further investigation of the attraction of vesicles to the active zone of the presynaptic membrane.

Animals↗
PubMed1977

Rubella--a reappraisal.

Rubella infection is reviewed and new information about congenital infection, possible sources of infection in pregnant women and the optimum ages and population groups for rubella vaccination is considered. Investigations required to confirm a suspected and possibly 'silent' infection during pregnancy are outlined.

Adolescent↗