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Biomedical subjects

P Gilbert

Publications and source records attributed to P Gilbert.

At least 199 records · Page 11Linked to original sources
PubMed1986

Isolated partial third nerve palsy following Le Fort I maxillary osteotomy in a patient with cleft lip and palate.

A rare case is reported of right sided isolated partial IIIrd (oculomotor) nerve palsy complicating a Le Fort I Wake osteotomy in a cleft patient. This lesion recovered spontaneously and completely by 8 weeks. Computed tomography failed to reveal a focal lesion to account for this complication, which was thought to be a neuropraxia caused either by transmitted force or accumulation of haematoma and/or oedema, perhaps related to abnormal anatomy inherent in cleft cases.

Adolescent↗
PubMed1986

The context of menopause: psychotropic drug use and menopausal status.

The menopause has been cited as a causal factor in psychotropic drug use among women in midlife. This paper first examines the stereotype of the menopausal woman and the theories which can be used to predict that she will be a high user of psychotropic medication. It then examines the actual use of psychotropics and the relationship between use and menopausal status using data from a study of 2500 women, aged 40-59, living in the Province of Manitoba, Canada.

Adaptation, Psychological↗
PubMed1986

Differentiation properties of renal collecting duct cells in culture.

In the present study, we were particularly interested in distinguishing specific patterns of structural and functional proteins in the collecting duct system of neonatal and adult kidneys and in cultured renal collecting duct epithelia in order to ascertain the degree of differentiation in the cultures. We studied the distribution of specific renal collecting duct cell markers using morphological, immunohistochemical and biochemical procedures. Cultured renal collecting duct epithelium undergoes maturation in vitro. Examples of morphological differentiation include the appearance of cilia and microvilli at the apical cell pole, and a basement membrane at the basal aspect of the epithelium. Tight junctions with five to seven strands separate the wide intercellular spaces from the apical cell surface. Physiological maturation from a 'leaky' to a 'tight' epithelium is evident from the acquisition of the alpha-subunit of Na/K-ATPase and the development of a high transepithelial potential difference and resistance. Biochemical differentiation is revealed by the expression of specific proteins. The simple-epithelium cytokeratins, PKK1 and PKK2, which are typical intracellular-matrix proteins of mature collecting duct epithelium, maintain the same distribution in cell culture as in neonatal and adult kidneys. An indicator of maturation in vitro is the expression of the collecting duct-specific proteins, PCD2 and PCD3. Newly developed monoclonal antibodies against these antigens reacted similarly with cultured cells and cells of the mature collecting duct system, but they did not label the embryonic ampullae in the cortex of neonatal rabbit kidneys. In contrast, a third collecting duct-specific protein, PCD1, is not expressed by the cultured cells, which indicates the retention of an embryonic characteristic in vitro. Embryonic collecting duct ampullae of the neonatal kidney in situ contain laminin during their development. Laminin is, however, absent in cultured collecting duct epithelium. Biochemical stimulation of the adenylate cyclase system by arginine vasopressin resulted in a twofold stimulation of the enzyme activity. This degree of stimulation is similar to that found in maturing kidneys of neonatal rabbits and indicates another embryonic feature of the cultures.

Animals↗
PubMed1986

Histological changes in rat testicles after short-term ischaemia.

A temporary pinching off of the spermatic cord was carried out in 100 male Wistar rats in order to evaluate the effect of a limited period of ischaemia on the testicular parenchyma. The animals were divided into four groups of equal number, and a certain period of ischaemia was chosen (15, 30, 45 and 60 min). The histological investigation of the testicle parenchyma was performed 2 months after the operation, the contralateral testicle serving as control. Already an ischaemia of 15 min leads to a statistically significant, irreversible damage of 53.5% of the seminiferous tubulus (p = 0.001). The degree of the damage does not increase up to an ischaemic period of 1 h. Since rat testicles have proven to be a model for the judgement of human fertility, operations on testicles which are combined with a temporary ischaemia of this organ, should be ended within a few minutes.

Animals↗
PubMed1986

[Metaraminol--an antidote in corpus cavernosum autoinjection therapy-induced prolonged erection].

Up to now 65 patients with erectile dysfunction were treated by means of corpus cavernosum-autoinjection-therapy (CAT). The only side effect observed were 6 prolonged erections, which could successfully be treated in 3 cases by puncture and aspiration of the corpora cavernosa. In another 3 cases prolonged erection subsided after an intracavernous injection of 2 mg metaraminol. Erection induced by CAT was immediately interrupted by metaraminol in 10 other patients.

Adult↗
PubMed1985

The structure of the mer operon.

The DNA sequence has been determined for a 3.8-kb region which encodes the mercury-resistance (mer) operon of the IncFII plasmid NR1. The sequence reveals 4 open reading frames which could encode proteins of 12,522, 9,429, 14,965, and 58,912 d corresponding to the 4 previously described Hg-inducible proteins detected in minicells carrying mer+ plasmids. The Hg(II) reductase protein sequence is about 90% homologous to that of Tn501, but the DNA sequence shows a homology of 60-70% to that of Tn501 except for short regions of very high homology. The entire mer region is 63.4% G-C overall. The region encoding the merR (positive regulatory) function has 3 possible open reading frames, 2 of which overlap in one direction and the third of which reads in the opposite direction. Attempts to visualize the polypeptide(s) encoded by the merR cistron were unsuccessful.

Bacteria↗
PubMed1985

The theory and relevance of continuous culture.

Batch cultures of micro-organisms which utilize typical laboratory media, generally result in rapidly dividing cultures (generation times less than 1 h). These are atypical of those found in natural environments. The continuous culture of micro-organisms allows either specific-growth-rate to be controlled, whilst maintaining the cells in a constant physical and chemical environment or a constant specific-growth-rate to be maintained whilst physico-chemical parameters of growth such as pH, temperature or nutrient availability are varied. Continuous culture therefore offers the prospect of in-vitro culture of micro-organisms in physiological states relevant to their natural habitats. This article introduces the concepts of continuous culture and discusses their relevance towards in-vitro models of infection and of antibiotic dosing.

Anti-Bacterial Agents↗
PubMed1984

Depolarization of cultured oligodendrocytes by glutamate and GABA.

Subpopulations of cultured oligodendrocytes from mouse spinal cord respond with depolarization to glutamate and GABA. Heterogeneity in the oligodendrocyte population was indicated by the observation that some cells respond to both GABA and glutamate, while others respond to only one and some are not responsive to either. Depolarizations are not mediated by an increase of [K+]o released from neurons. The response to GABA was blocked in Na+-free solution and is not accompanied by a change in input resistance. Several other neurotransmitters did not induce changes in membrane potential.

Animals↗
PubMed1984

A monoclonal antibody which detects a 125 kd glycoprotein on embryonal carcinoma cells and is mitogenic for murine spleen cells.

The isolation and characterisation of a monoclonal antibody (2H9), selected for reactivity against murine teratocarcinoma stem cells, is described. This antibody recognizes one major glycoprotein on the surface of embryonal carcinoma (EC) cells but detects multiple glycoprotein species on various murine or human derived cell types. The binding of the antibody to cells is abolished by treatment with periodate or neuraminidase. These results suggest that 2H9 antibody detects a carbohydrate determinant; this is apparently distinct from other anti-EC reactive monoclonal antibodies and a variety of lectins. These antibodies are mitogenic for a population of lymphocytes in murine spleen. The antibodies recognize numerous cell surface glycoproteins on the surface of the spleen cells.

Animals↗
PubMed1984

Interaction of some polyhexamethylene biguanides and membrane phospholipids in Escherichia coli.

The interaction between some polyhexamethylene biguanides and the cell envelope of Escherichia coli has been investigated. An amine-ended dimer, (AED, n = 2), a polydisperse mixture (ICI plc) available as the active ingredient of Vantocil IB, (PHMB, n = 5.5), and a high molecular weight fraction, (HMW, n = greater than or equal to 10) of PHMB were used. The sensitivity of batch cultures depleted of magnesium (M-dep), phosphorus (P-dep) or glycerol (C-dep) towards the biocides was assessed by monitoring the rate and extent of potassium ion leakage. P-dep suspensions were particularly resistant to all these agents and possessed less than half the quantity of phospholipid of other cell types. This was compensated for by a proportionate increase in fatty acid and neutral lipid content of the cells. The reduction in phospholipid content was accounted for by decreases in phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). Diphosphatidylglycerol (DPG) and phosphatidylserine (PS) content of the cultures remained unaffected by the depleting nutrient. Fourier-transform n.m.r. spectroscopy was used to study proton nuclei during the interaction of HMW, AED and PHMB with various phospholipid-vesicle preparations. The results strongly suggest that the biocides acted preferentially on the acidic phospholipids PG and DPG, rather than towards PE or PS. Resistance of P-dep cultures therefore reflected reductions in PG content. A molecular basis for the interaction of these compounds and membranes is proposed.

Biguanides↗
PubMed1984

gamma-Aminobutyric acid directly depolarizes cultured oligodendrocytes.

gamma-Aminobutyric acid (GABA) depolarizes in a dose-dependent manner approximately one-third of all immunologically identified oligodendrocytes in cultures of mouse spinal cord. Measurements of [K+]o indicate that the response to GABA is not due to K+ released from active neurons. The depolarization is not accompanied by a change in cell input resistance. Replacement of sodium in the bathing solution abolishes the entire response, whereas ouabain only inhibits the repolarization phase. Current clamp experiments with two separate intracellular electrodes show that the depolarization increases at more positive potentials while the repolarization increases at more negative potentials. Bicuculline and picrotoxin but not nipecotic acid reduce the GABA effect. Pentobarbital and chlordiazepoxid also reduce the GABA-induced depolarization. Muscimol produces a depolarization similar to that of GABA. Heterogeneity in the oligodendrocyte population is indicated by the observation that some cells respond to both GABA and glutamate, while others respond only to one and some are not responsive to either.

Animals↗
PubMed1984

Injury and recovery of Escherichia coli ATCC 8739 from treatment with some polyhexamethylene biguanides.

The action of some polyhexamethylene biguanides upon Escherichia coli has been investigated. An amine-ended-dimer (n = 2), a polydisperse mixture (n = 5.5) and a high molecular weight fraction (n greater than 10) of the compounds were employed. The three compounds caused damage and disruption of the cell envelope indicated by changes in permeability towards the dye 2-p-toluidinylnaphthylene-6-sulphonate. This damage was shown to be reversible below certain critical concentrations of the biocides. Prolongation of treatment time did not increase the extent of non-recoverable injury nor influence those critical concentrations of biocide initiating it. Recovery processes were rapid and complete within 1 min. The inclusion of an inhibitor of respiration, antimycin A, in the recovery medium did not reduce the rate of recovery by damaged cells.

Antimycin A↗
PubMed1984

Binding of some polyhexamethylene biguanides to the cell envelope of Escherichia coli ATCC 8739.

Absorption and antibacterial action of some polyhexamethylene biguanides upon Escherichia coli has been investigated. An amine-ended-dimer (AED) (n = 2), a polydisperse mixture sold by ICI Limited as the active ingredient of vantocil IB (PHMB) (n = 5.5), and a high molecular weight fraction of PHMB (HMW, n greater than or equal to 10) were used. Bactericidal activity was determined over a range of pH (5-9). Similarly, adsorption of drug to the cell surface, indicated by changes in electrophoretic mobility, and overall drug absorption by the cells were determined. Maximal activity occurred at pH 6 for PHMB and HMW and at pH 5 for AED. This corresponded to minimal surface adsorption and maximal distribution of drug to the underlying cytoplasm and cytoplasmic membrane. Uptake of drug corresponded to high affinity isotherms and indicated a rapid transfer of biocide into the cells following their initial interaction at the surface.

Biguanides↗