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Biomedical subjects

R King

Publications and source records attributed to R King.

At least 19 recordsLinked to original sources
PubMed1992

Effect of temperature and medium composition on mycelial growth of Streptomyces tendae in submerged culture.

To investigate the influence of culture conditions on growth of filamentous bacteria in submerged culture, S. tendae was cultivated at various temperatures and in various media. For this purpose, a temperature-controlled growth chamber was constructed, which allows the cultivation of filamentous bacteria and fungi oxygen saturated medium. To observe the development of mycelia emerging from spores, this growth chamber was mounted on a microscope stage and series of images were analyzed by an image processing system. Growth kinetics obtained in liquid culture were identical to those determined on solid media. Specific growth rate and apical extension rates of individual hyphae seemed to be higher than those observed on solid media, due to a better supply of medium in submerged culture. A two-fold increase in specific growth rate, mean apical extension rate and branching rate was observed when the temperature was increased from 27 degrees C to 37 degrees C, therefore, the length of the hyphal growth unit was not changed. Growth in synthetic media used here was considerably slower compared with complex medium. A decrease in glucose concentration from 40.0 g l-1 to 1.0 g l-1 resulted in an increase in branching rate and specific growth rate, while apical extension rate of individual hyphae was unchanged.

Bacteriological Techniques↗
PubMed1992

Nutritional control of nikkomycin and juglomycin production by Streptomyces tendae in continuous culture.

Continuous cultures with Streptomyces tendae revealed some interesting facts. In a continuous culture running for more than 2500 h the production of either nikkomycines or juglomycins could be selected by varying the feed composition. Decreasing the phosphate supply in the feed broth from the initial concentration of 2.5 mM to 1.0 mM enhanced the productivity of nikkomycins and decreased the productivity of juglomycins. When switching back to the initial conditions of the experiment after 2000 h nearly the same production behaviour as at the beginning of the fermentation could be observed. This indicated a stable behaviour of the population with regard to nikkomycin productivity. The long continuous fermentation showed the ability of S. tendae Tü 901/8c to produce nikkomycin at a high level for at least 1500 h. In a second continuous culture it was shown that the productivity of the nikkomycins and juglomycins decreased and increased, respectively, with increasing dilution rate. Comparing batch cultures with continuous fermentations, higher juglomycin productivity was found in the latter. These facts indicate that the strain responds to complex interacting physiological controls, by producing either nikkomycins or juglomycins in a higher amount.

Aminoglycosides↗
PubMed1992

Production and characterization of recombinant insulin-like growth factor-I (IGF-I) and potent analogues of IGF-I, with Gly or Arg substituted for Glu3, following their expression in Escherichia coli as fusion proteins.

The development of an efficient expression system for insulin-like growth factor-I (IGF-I) in Escherichia coli as a fusion protein is described. The fusion protein consists of an N-terminal extension made up of the first 46 amino acids of methionyl porcine GH ([Met1]-pGH) followed by the dipeptide Val-Asn. The latter two residues provide a unique hydroxylamine-sensitive link between [Met1]-pGH(1-46) and the N-terminal Gly of IGF-I. Downstream processing of the fusion proteins involved isolation of inclusion bodies, cleavage at the Asn-Gly bond, refolding of the reduced IGF-I peptide and purification to homogeneity. This expression system was also used to produce two variants of IGF-I in which Glu3 was substituted by either Gly or Arg to give [Gly3]-IGF-I and [Arg3]-IGF-I respectively. Production of milligram quantities of IGF-I peptide was readily achieved. The purity of the IGF-I, [Gly3]-IGF-I and [Arg3]-IGF-I was established by high-performance liquid chromatography and N-terminal sequence analysis. [Gly3]-IGF-I and [Arg3]-IGF-I were more potent than IGF-I in biological assays measuring stimulation of protein synthesis and DNA synthesis or inhibition of protein breakdown in rat L6 myoblasts. Both analogues bound very poorly to bovine IGF-binding protein-2 and slightly less well than IGF-I to the type-1 receptor on rat L6 myoblasts. We conclude that reduced binding to IGF-binding proteins rather than increased receptor binding is the likely explanation for the greater biological potency of the analogues compared with IGF-I.

Amino Acid Sequence↗
PubMed1992

Novel recombinant fusion protein analogues of insulin-like growth factor (IGF)-I indicate the relative importance of IGF-binding protein and receptor binding for enhanced biological potency.

An efficient expression system in Escherichia coli for several biologically active insulin-like growth factor-I (IGF-I) fusion peptide analogues is described. These novel IGF-I fusion protein analogues have properties that make them very useful reagents in the investigation of IGF-I action. The analogues comprise an IGF-I sequence and the first 11 amino acids of methionyl porcine growth hormone (pGH) and include [Met1]-pGH(1-11)-Val-Asn-IGF-I, which contains the authentic IGF-I sequence, and two analogues, [Met1]-pGH(1-11)-Val-Asn-[Gly3]-IGF-I and [Met1]-pGH(1-11)-Val-Asn-[Arg3]-IGF-I, where Glu-3 in the human IGF-I sequence has been replaced by Gly or Arg respectively. The three peptides are referred to as Long IGF-I, Long [Gly3]-IGF-I or Long [Arg3]-IGF-I depending on the IGF-I sequence present. Production of the purified fusion peptides was aided by folding the reduced and denatured fusion peptide sequence under conditions that gave very high yields of biologically active product. Introduction of a hydrophobic N-terminal extension peptide appears to facilitate the correct folding of the IGF-I analogues compared with that obtained previously when folding normal-length IGFs. The biological activities of the IGF-I fusion peptides were compared with authentic IGF-I and the truncated analogue, des(1-3)IGF-I. In L6 rat myoblasts, all the analogues were more potent than authentic IGF-I in their abilities to stimulate protein and DNA synthesis and inhibit protein breakdown. In H35 hepatoma cells, where the IGFs act through the insulin receptor, the Long IGF-I analogues maintained a similar potency relative to IGF-I as was observed in the L6 myoblasts. The order of biological potency in cell lines secreting IGF-binding proteins (IGFBPs) into the medium was Long [Arg3]-IGF-I-des(1-3)IGF-I greater than Long [Gly3]-IGF-I greater than Long IGF-I greater than IGF-I. In chicken embryo fibroblasts, a cell line that does not secrete detectable IGFBPs into the medium, Long [Arg3]-IGF-I, was less potent than IGF-I. Investigation of receptor and IGFBP association by these analogues reinforced our previous findings that N-terminal analogues of IGF-I show increased biological potency due to changes in the degree of their IGFBP interactions.

Amino Acid Sequence↗
PubMed1992

Psychoanalysis, science and clinical practice.

The question of the relationship between psychoanalysis and science, and the place of psychoanalysis in clinical practice is reviewed. A commonly held view that the central question is whether or not psychoanalysis is scientific is challenged. It is argued instead that psychoanalysis, science and clinical practice are epistemologically independent fields and attempts to subsume one within the other are unproductive. Psychoanalysis may have as much to say concerning the epistemological basis of science as science has to say concerning the epistemological basis of psychoanalysis. Only a proper appreciation of this enables the question of the relationship between psychoanalysis and clinical practice to be adequately examined.

Australia↗
PubMed1992

A comparison of two methods of breastfeeding management.

This study has demonstrated that, in a small group of 58 mothers, specific advice focused on establishing easier patterns of breastfeeding resulted in more of them continuing to breastfeed their babies for a longer period post-partum, with a less intense feeding pattern and the use of fewer complementary bottles of formula or other liquids, than did those given only the standard advice about breastfeeding. Current advice might be reviewed to continue to encourage demand breastfeeding but to emphasise the establishment of easier patterns of breastfeeding that optimise the mother-infant interaction.

Adult↗
PubMed1991

Thoracoscopic talc poudrage pleurodesis for chronic recurrent pleural effusions.

OBJECTIVE: To assess the effectiveness of thoracoscopic talc poudrage for the treatment of chronic pleural effusions. DESIGN: Prospective evaluation. SETTING: Kaiser-Permanente Hospital. PATIENTS: Forty-seven consecutive patients with recalcitrant pleural effusions, referred for thoracoscopy. INTERVENTION: Patients received general or local anesthesia; 42 had a 7-mm rigid thoracoscopic examination followed by insufflation of 5 mL of talc. Patients then had chest-tube drainage. MEASUREMENTS: We recorded clinical characteristics, final diagnosis, procedure-related pain and morbidity, days of hospitalization, patient-reported degree of symptom relief, and chest roentgenographic results at 1, 3, and 12 months. All patients were followed for 16 months or until death. MAIN RESULTS: Of 39 evaluable patients, all reported prolonged relief of effusion-related dyspnea. Radiographic results confirmed the elimination of pleural effusions in 34 patients (87%), including all 11 with benign conditions and 23 of 28 (82%) with malignancies. Treatment failed in three patients because of entrapped lung and in two patients with mesotheliomas whose effusions recurred more than a year after treatment. No procedure-related mortality or morbidity was found. Ambulatory patients required hospitalization for a mean of 3.9 days (range, 2 to 11 days). Mild pain was reported by some patients. The mean duration of chest-tube drainage was 2.7 days (range, 1 to 9 days). Patients with malignant disease lived an average of 12.4 months (range, 1 to 61 months) after the procedure. CONCLUSIONS: Thoracoscopic talc poudrage is an effective pleural sclerosing technique and is relatively painless.

Adult↗
PubMed1991

Bovine probursin tetradecapeptide contains amino acid sequence from somatostatin, tuftsin and bursin.

The B cell differentiating tripeptide bursin (lysyl-histidyl-glycyl-amide) is found in avian and mammalian bone marrow and in epithelial cells of the avian bursa of Fabricius and mammalian intrahepatic bile ducts. We now report the structure of probursin (Phe-Phe-Trp-Lys-Thr-Lys-Pro-Arg-Lys-His-Gly-Gly-Arg-Arg) isolated from bovine bone marrow and liver. Amino acids 1-5 correspond to the active site of somatostatin, 5-8 to tuftsin and 9-11 to bursin. Intact probursin has the biological activity of both somatostatin and bursin, and known enzyme cleavages could release free tuftsin, although intact probursin has low tuftsin activity. Probursin and its component peptides could regulate other bone marrow functions in addition to B cell differentiation, and, in mammals, could also regulate the function of hepatocytes and Kupffer cells after transport to the hepatic sinusoids via a local portal system involving the peribiliary capillary plexus.

Amino Acid Sequence↗
PubMed1991

Cloning and functional characterization of the rat glutamine synthetase gene.

Glutamine synthetase catalyzes the formation of glutamine from glutamate and ammonia. It plays a central role in both amino acid neurotransmitter metabolism and ammonia detoxification in the central nervous system. Glutamine synthetase expression is regulated in developmental, hormonal, and in tissue- and cell-specific manners. We have cloned a full-length cDNA coding for rat glutamine synthetase, and have found an AT-rich area of conservation in the 3' untranslated regions between rat, mouse, and chicken, which may play a part in the regulation of the stability of the glutamine synthetase message. We have also cloned and mapped the gene coding for rat glutamine synthetase, and identified, by sequence analysis, areas potentially important for the regulation of glutamine synthetase transcription. Transient transfection of a variety of cell lines with deletion constructs of the glutamine synthetase promoter driving a chloramphenicol acetyltransferase reporter gene functionally demonstrates regions of the promoter containing elements important for transcriptional regulation.

Amino Acid Sequence↗
PubMed1991

Developmental changes in growth hormone, insulin-like growth factors (IGF-I and IGF-II) and IGF-binding proteins in plasma of young growing pigs.

The relationship between plasma concentrations of normally secreted GH and insulin-like growth factor-I (IGF-I) was investigated in pigs after weaning. Frequent blood sampling for between 12 and 24 h showed that plasma GH was pulsatile in pigs of 10, 20 and 35 kg liveweight. Pulses were brief in duration, low in amplitude and variable in frequency. Basal and average daily plasma concentrations of GH changed significantly with development, increasing by about 50% between 10 and 20 kg liveweight. Concentrations of IGF-I in plasma showed little or no evidence of diurnal periodicity and were not increased by GH pulses. Average daily concentrations of both IGF-I and IGF-II in plasma progressively increased between 10 and 35 kg liveweight, as did the total desaturated IGF-binding protein (IGFBP) activity of plasma. A strong positive correlation was observed between the total concentration of IGFs (IGF-I plus IGF-II) in the circulation and plasma IGFBP activity. The developmental rise in IGFBP activity of plasma was associated with increased labelling with 125I-labelled human IGF-II in ligand blots of binding proteins of apparent molecular masses greater than 200, 50, 43 and 29 kDa. One class of binding proteins of 34.5 kDa decreased with development. This study of young growing pigs shows that normally secreted endogenous GH exerts no significant immediate control over plasma IGF-I concentrations, and that plasma levels of IGF-I and IGF-II increase with maturation in this species.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Frequency of asymptomatic hepatitis types B and C in an inner city community and relation to possible risk factors.

The frequency of asymptomatic carriage of the hepatitis virus types B and C in an inner city area (South London) was assessed in a survey of 1002 subjects attending their General Practitioner for minor, non-hepatic complaints. Ten subjects were seropositive for hepatitis B surface antigen (HBsAg) (1 per cent), but only one, who declined liver biopsy, had any clinical laboratory evidence of hepatitis B virus-related chronic liver disease. Carriage of, and exposure to, hepatitis B virus was significantly more frequent among people born outside the UK/Eire and those with a history of jaundice. Among people of Caribbean origin the frequency of hepatitis B virus markers fell from 31 per cent among those born in the Caribbean to 11 per cent amongst second generation subjects born in this country. Despite careful counselling, offers of further investigation and treatment of those affected, and vaccination of vulnerable children or partners, were often declined. Four percent of the same population had antibodies to the hepatitis C virus using the Ortho anti-hepatitis C virus enzyme-linked immunosorbent assay but this figure fell to 0.9 per cent when a second test, based on synthetic peptides rather than a recombinant antigen, was used. None had any abnormality of standard liver function tests. Chronic asymptomatic carriage of hepatitis, particularly in inner city areas, may be more common than previously recognized. Effective use of antiviral agents and vaccination will be limited until appropriate health education dispels the widespread misconceptions and fears associated with a diagnosis of chronic viral hepatitis.

Adult↗
PubMed1991

[Urinary incontinence in the paraplegic woman: surgical treatment].

It is described by first time a technic used for the treatment of urinary incontinence on the paraplegic patients that restore the capacity of self control and micturition equivalent to a normal woman, without use of prosthesis. Basically, it consists in a procedure of an aponeurotic belt (Ingelheim type) but it is tractioned by a fingering of the anterior rectum of the abdomen or oblique. For this reason, the tonic contraction or the enforcement produces the elevation of the rear lip of the vesical neck and its sure shut, such as happens in the normal woman. The relaxing opens the neck for the micturition. The procedure is simple, with common instrumental, without prosthesis and at low cost. Two patients have been operated so far, with excellent results and they were controlled for 5 years until now presenting normal conditions.

Adult↗