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Biomedical subjects

K Smith

Publications and source records attributed to K Smith.

At least 415 records · Page 23Linked to original sources
PubMed1989

Quantification of epidermal growth factor in human breast cyst fluids: correlation with dehydroepiandrosterone-sulphate and electrolyte concentrations.

Epidermal growth factor (EGF), dehydroepiandrosterone (DHA)-sulphate and [Na+] and [K+] were assayed in 78 cyst fluids from patients with a palpable breast cyst. Epidermal growth factor was detected in all but 2 cysts, the mean value +/- SEM being 506.2 +/- 39.3 ng/ml, with a range of 0-1,599 ng/ml. When the cyst fluids were sub-divided according to their [Na+]:[K+] ratio, group A cyst fluids ( [Na+]:[K+] less than 3) had a significantly higher (p less than 0.001) level of EGF than group B cyst fluids ([Na+]:[K+] greater than 3). Furthermore, the relationship between EGF and [Na+] and [K+] and between EGF and DHA-sulphate seemed to differ between the 2 cyst types and each cyst type was therefore analyzed separately.

Aged↗
PubMed1989

Amplification and overexpression of c-myc proto-oncogene correlate with the loss of glucocorticoid dependence in rodent cells transformed by human papillomavirus type 16.

Transformation of baby mouse kidney epithelial cells by human papillomavirus (HPV) type 16 is dependent both upon the cooperating oncogene and on the hormonal conditions after transfection. With v-fos as the oncogene, the transformed cells require glucocorticoid hormone, such as dexamethasone, for proliferation. This requirement is lost on continued passage of cell lines, and the cells become dexamethasone independent. Steroid-independent cell lines are also produced by growth of the HPV16/v-fos cells in 17 beta-estradiol following transfection, but cell lines produced in this manner showed no subsequent requirement for estradiol or dexamethasone. Expression of the c-myc proto-oncogene was measured in dexamethasone-dependent and independent cell lines. Dexamethasone-dependent cell lines all exhibited low level c-myc expression, but this markedly increased in the cell lines that had become dexamethasone independent as a result of continued in vitro growth. The low level of c-myc expression in some early passage dexamethasone-dependent cell lines appears to be associated with rearrangement of the c-myc locus, whereas late passage dexamethasone-independent cell lines contain amplified c-myc sequences. Dexamethasone-independent cell lines derived by growth in 17 beta-estradiol showed higher levels of c-myc expression, together with higher c-myc copy number, than dexamethasone-dependent lines. Taken together, these studies indicate that the steady-state level of c-myc expression affects the continued requirement of HPV16-transformed cells for dexamethasone.

Cell Division↗
PubMed1989

Skeletal muscle glutamine transport, intramuscular glutamine concentration, and muscle-protein turnover.

This article reviews work we have carried out to investigate (1) the transport mechanisms responsible for the high distribution ratio of free glutamine commonly observed in skeletal muscle; (2) the fall in the distribution ratio that accompanies starvation, injury and chronic disease, whether directly involving muscle or not; and (3) the effect of modulation of intracellular free-glutamine concentration on protein synthesis and breakdown in skeletal muscle. We suggest that the results are consistent with the controlling role of the muscle membrane glutamine-sodium cotransporter in the regulation of the intracellular glutamine pool, the existence of pathophysiological mechanisms for the modulation of intramuscular glutamine and anabolic effects of glutamine in promoting protein synthesis, with a smaller effect in reducing protein breakdown. The mechanisms by which glutamine affects skeletal muscle protein turnover, and thus muscle protein balance, and the extent of the net flow of amino acids between the periphery and the viscera are unknown as yet, but the results suggest that modulation of transporter activity may offer the possibility of therapeutic intervention to reduce muscle wasting associated with injury and disease.

Animals↗
PubMed1989

A spectrophotometric procedure for the determination of objective measurements of equine spermatozoan motility.

A spectrophotometric procedure was developed and evaluated for the objective measurement of equine spermatozoan motility. A 100 mul sample of a sperm suspension, prepared by the removal of seminal plasma, was layered under a column of optically clear medium in a specially designed spectrophotometric cuvette maintained at 37 degrees C. Changes in light transmittance above the interface of the sperm suspension and medium were recorded on chart paper. As sperm cells swam into the medium, a decrease in light transmittance was recorded as a deflection on the chart paper. Chart recordings were analyzed for the height (cm) and time (min) to the peak deflection. To standardize the procedure, a fixed number of cells (1x10(9)) were used to prepare suspensions of 300x10(6) cells/ml. Coefficients of variation for mean values obtained under these conditions after the evaluation of five ejaculates from a given stallion were estimated at between 10 and 12%. Correlations between swim-up measurements and computer-assisted semen analysis demonstrated that the percentage of motile cells and mean velocity (mum/sec) of motile cells influenced swim-up measurements. Described here is a simple and inexpensive procedure to determine objective measurements of spermatozoan motility that may have application in semen evaluation and fertility testing in the stallion.

Journal Article↗
PubMed1989

Non-governmental organizations in the health field: collaboration, integration and contrasting aims.

Non-governmental organizations, from being voluntary agencies often with relief or religious mission orientations, have become very important players in the field of social development. In this paper something is given of their evolution, diversity, aims and activities; and of the important role they now play in many instances, as well as some of the obstacles to collaboration, co-ordination and integration at different levels of operation--internationally, nationally and locally.

Financing, Government↗
PubMed1989

Epidermal growth factor receptor in human bladder cancer: a comparison of immunohistochemistry and ligand binding.

Epidermal growth factor receptors were measured in biopsies from patients with newly diagnosed bladder cancer. Two methods to detect these receptors were compared: immunohistochemical staining of frozen sections, and a ligand binding study using radiolabeled epidermal growth factor and tumor cell membranes. We studied 101 patients by immunohistochemistry and 47 patients by both methods. An association was found between immunohistochemical positivity for epidermal growth factor receptors and high tumor stage (p less than 0.001). Thus, most of the muscle invasive tumors were positive (35 of 49, 71 per cent) and more stage pT1 tumors were positive (8 of 18, 44 per cent) than were stage pTa tumors (5 of 34, 15 per cent, p less than 0.05). The ligand binding study was slightly more sensitive in detecting receptors than immunohistochemistry (30 of 47, 64 per cent and 25 of 47, 53 per cent, respectively). Greater amounts of receptors were found in muscle invasive tumors compared to tumors not invading muscle (p less than 0.05). A significant association was found between the 2 methods in the detection of receptors (p less than 0.001) and no discrepancies were found between the 2 methods in tumors containing high levels of receptors. Immunohistochemistry provides a satisfactory method to detect receptors in tumors with high levels of receptors, although ligand binding is more sensitive in tumors with low levels of receptors.

Adult↗
PubMed1989

Increase in anterior tibialis muscle protein synthesis in healthy man during mixed amino acid infusion: studies of incorporation of [1-13C]leucine.

1. Anterior tibial muscle protein synthesis in seven healthy postabsorptive men was determined from increases in muscle protein bound leucine enrichment during a primed continuous infusion of L-[1-13C]leucine. Biopsies were taken 30 min after the beginning of leucine infusion (when plasma 13C enrichment was steady), 240 min later during continued fasting and again after 240 min of infusion of a mixed amino acid solution which increased plasma total amino acid concentrations by 37%. The mean enrichment of 13C in plasma alpha-ketoisocaproate was used as an index of the enrichment of the precursor pool for leucine metabolism. 2. Anterior tibial muscle mixed protein synthetic rate during fasting was 0.055 (SD 0.008)%/h and this increased by an average of 35% during infusion of mixed amino acid to 0.074 (SD 0.021)%/h (P less than 0.05). 3. Whole-body protein breakdown (expressed as the rate of endogenous leucine appearance in plasma) was 121 (SD 8) mumol h-1 kg-1 during fasting and decreased (P less than 0.01) by an average of 12% during amino acid infusion. Leucine oxidation was 18 (SD 3) mumol h-1 kg-1 during fasting and increased (P less than 0.001) by 89% during amino acid infusion. Whole-body protein synthesis (non-oxidative leucine disappearance) was 104 (SD 6) mumol h-1 kg-1 during fasting and rose by 13% (P less than 0.001) during mixed amino acid infusion. 4. 13C enrichment of muscle free leucine was only 61 (SD 19)% of that in plasma alpha-ketoisocaproate and this increased to 74 (SD 16)% (P less than 0.02) during mixed amino acid infusion. 5. The results suggest that increased availability of amino acids reverses whole-body protein balance from negative to positive and a major component of this is the increase in muscle protein synthesis.

Amino Acids↗
PubMed1989

Single-dose pharmacokinetics of intravenous ampicillin plus sulbactam in healthy elderly and young adult subjects.

The pharmacokinetics of intravenous ampicillin and sulbactam, a beta-lactamase inhibitor, were evaluated in two different age groups. Twelve healthy elderly subjects (age 65-93 years) and 12 healthy young adult subjects (age 20-35 years) received both a dose of ampicillin 1 g plus sulbactam 0.5 g and a higher dose of ampicillin 2 g plus sulbactam 1 g after a one-week period between doses. A reverse-phase high-pressure liquid chromatography method was used for the quantitation of ampicillin and sulbactam in serum and urine. The pharmacokinetic parameters for both ampicillin and sulbactam were calculated by computer-based two-compartment nonlinear model. After a 30-min infusion, serum concentrations of both drugs declined in a biexponential manner for both doses. Elderly subjects demonstrated significantly lower total clearances (Clt) than young adult subjects of ampicillin 1 g (220.0 +/- 104.2 vs 360.0 +/- 95.8 ml/min/1.73 m2), ampicillin 2 g (72.6 +/- 36.6 vs 306.8 +/- 109.77 ml/min/1.73 m2), sulbactam 0.5 g (122.3 +/- 47.8 vs 263.9 +/- 93.7 ml/min/1.73 m2), and sulbactam 1 g (171.2 +/- 85.8 vs 391.7 +/- 70.8 ml/min/1.73 m2), respectively. Significance was defined as P less than 0.05. Renal clearance was also significantly reduced in the elderly subjects. Area under the curve was found to be significantly increased in the elderly subjects compared to the young subjects for both ampicillin and sulbactam as were the beta elimination half-lives. No significant difference in the apparent volume of distribution, when adjusted for body weight, was found for either sulbactam (P greater than 0.95) or ampicillin (P greater than 0.95) between the two groups. Linear regression analysis revealed that age was significantly correlated with the Clt of ampicillin 1 g (r = 0.85, P less than 0.001), ampicillin 2 g (r = 0.90, P less than 0.001), sulbactam 0.5 g (r = 0.80, P less than 0.001), and sulbactam 1 g (r = 0.93, P less than 0.001). A multivariate analysis showed a slight improvement in correlation when creatinine clearance was added to age and compared with Clt. Urinary recovery of both ampicillin and sulbactam was approximately 60% after 14 h.

Adult↗
PubMed1989

Effects of therapeutic percutaneous electrical stimulation of atrophic human quadriceps on muscle composition, protein synthesis and contractile properties.

The effects of percutaneous electrical stimulation (70 V, 300 microseconds pulses at 30 Hz) on muscle composition and rate of protein synthesis were studied in seven patients with quadriceps atrophy secondary to unilateral osteoarthritis of the knee (stimulated group). Quadriceps were stimulated on the affected side for 1 h per day. The results were compared to those from seven patients who did not use a muscle stimulator (control group), in whom muscle biopsy at surgery provided evidence of wasting of tissue protein on the side of osteoarthritis (normal leg 608 +/- 266 micrograms protein micrograms-1 DNA, affected leg 256 +/- 100 micrograms protein micrograms-1 DNA, means +/- SD, P less than 0.05; type I fibre diameters: normal 53.2 +/- 6.7 microns, affected 43.8 +/- 4.0 microns, P less than 0.05). In patients who had received stimulation there was no residual difference between the legs in either muscle protein concentration (normal 411 +/- 168 micrograms protein micrograms-1 DNA, affected 373 +/- 112 micrograms protein micrograms-1 DNA) or fibre diameter (type I diameters: normal 56.1 +/- 7.8 microns, affected 58.0 +/- 10.7 microns). Stimulation did not influence the ratios of muscle force elicited by acute stimulation at 20 and 50 Hz (normal 75 +/- 15%, affected 79 +/- 15%), or rates of muscle relaxation (percentage losses of tetanic force 10 ms-1: normal 7.66 +/- 1.2%, affected 8.67 +/- 2.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Photosensitization with derivatives of chlorophyll.

The properties of several chlorophyll derivatives were examined: the methyl esters of pheophorbide A, pheophorbide B and pheophytin. In spite of structural differences, all products were equally effective sensitizers in vitro and were localized equally well by murine tumors in vivo after 1 h. But only the pheophytins persisted at neoplastic loci for 24 h. There was no evidence of hydrolysis of the methyl esters, but the phytyl ester linkage was labile in vivo.

Animals↗
PubMed1989

Prolonged converting enzyme inhibition in non-modulating hypertension.

Patients with normal- or high-renin non-modulating essential hypertension fail to shift their adrenal sensitivity on a low sodium diet in response to an infusion of angiotensin II (Ang II). In a prior study, 72 hours of converting enzyme inhibition (CEI) partially corrected this subnormal aldosterone response to Ang II in patients with non-modulating hypertension. Since it was uncertain whether the failure to restore normal adrenal responsiveness reflected a continued abnormality or an insufficient duration of CEI, the present study was performed wherein subjects were studied before CEI and then 72 hours and 6 weeks after CEI. Adrenal and renovascular responses were assessed in 13 subjects with normal- or high-renin hypertension in response to an infusion of Ang II (0.3, 1.0, and 3.0 ng/kg/min) in balance on a 10 meq Na+/100 meq K+ diet. Eight of 13 had a normal plasma aldosterone increment above control levels (greater than or equal to 15 ng/dl) and were classified as modulators; the remaining subjects (five of 13) were classified as non-modulators. Enalapril was then administered for 72 hours and 6 weeks, and the assessment of the Ang II dose-response relations was repeated. In the modulators, there was no change compared with levels before CEI in the aldosterone dose-response curve or threshold sensitivity to infused Ang II at either 3 days or 6 weeks after CEI administration. In the non-modulators, CEI for 72 hours partially restored aldosterone responsiveness, but more prolonged CEI for 6 weeks completely corrected the defect, restoring aldosterone responsiveness on a sodium-restricted diet to that seen in modulators and in normotensive control subjects.(ABSTRACT TRUNCATED AT 400 WORDS)

Aldosterone↗
PubMed1989

Lipolytic surface remnants of triglyceride-rich lipoproteins are cytotoxic to macrophages but not in the presence of high density lipoprotein. A possible mechanism of atherogenesis?

Hypertriglyceridemic (HTG) serum, lipolyzed in vitro by purified bovine milk lipoprotein lipase, was found to be cytotoxic to cultured macrophages. Surviving macrophages contained numerous lipid inclusions similar to those found in foam cells. Individual lipoprotein fractions isolated from the lipolyzed HTG serum, including HDL, were also cytotoxic. Lipolysis of isolated lipoprotein fractions (either HTG or normal) allowed localization of cytotoxicity to postlipolysis remnant VLDL and chylomicron particles. The presence of a critical concentration of HDL in either the lipolysis mixture or the culture dishes inhibited the cytotoxicity. Below this critical concentration HDL itself became cytotoxic, producing lipid inclusions in surviving macrophages. The lipid fraction of the cytotoxic remnants contained the cytotoxic factor(s); neither FFA nor lysolecithin alone could account for this cytotoxicity. Postprandial lipemic sera from subjects with a brisk chylomicron response, when lipolyzed in vitro, were cytotoxic to cultured macrophages; neither fasted sera from these subjects, nor postprandial sera from normolipidemic subjects with a normal chylomicron response, were cytotoxic. Postheparin (in vivo lipolyzed) serum and its isolated lipoprotein fractions obtained 30 min after heparin injection in subjects with HTG were shown to be cytotoxic to macrophages; by 60 min most of the cytotoxicity had disappeared. The postprandial and postheparin observations support an in vivo significance for remnant-associated cytotoxicity. We hypothesize that cytotoxic remnants of lipolyzed VLDL and chylomicrons may be one of the major atherogenic lipoproteins. Further, we suggest that inhibition of the cytotoxicity of these remnants may be one important way that HDL prevents atherosclerosis.

Animals↗
PubMed1989

Prognostic factors for response and survival after high-dose cyclophosphamide, carmustine, and etoposide with autologous bone marrow transplantation for relapsed Hodgkin's disease.

Sixty-one patients with relapsed Hodgkin's disease who had failed a mechlorethamine, vincristine, procarbazine, and prednisone (MOPP)- and a doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD)-like regimen were treated with a high-dose combination chemotherapy containing cyclophosphamide, carmustine, and etoposide (CBV) and autologous bone marrow transplantation (ABMT). Fifty-nine patients were treated in relapse and two were intensified early in third remission. Following therapy, 29 patients (47%) were in complete remission (CR), 18 patients (30%) achieved a partial response (PR), and 14 patients (23%) had progressive disease (PD). Among the partial responders, six patients achieved a CR following addition of local radiation therapy to sites of residual nodal disease. For a minimum follow-up of 2 years, 23 patients (38%) are alive and free of disease. High-dose CBV therapy produced severe myelosuppression, and there were four (7%) treatment-related deaths. A multivariate analysis identified failure of more than two prior chemotherapy treatments and poor performance status as important adverse risk factors for survival. Patients who had no adverse risk factor and/or were intensified with CBV while Hodgkin's disease was still responding to conventional chemotherapy, had a CR rate of 63%, with 77% projected 3-year survival; whereas, all other patients had a CR rate of 31%, and a projected 3-year survival of only 18%. Our results demonstrated that CBV and ABMT can induce remission duration of 2 years or greater in a significant proportion of patients with relapsed Hodgkin's disease.

Adolescent↗
PubMed1989

Freeze-fracture study of the intercellular junctions in bronchiolo-alveolar carcinoma (Clara cell type).

Two bronchiolo-alveolar carcinomas of Clara cell type have been studied by thin section and freeze-fracture techniques. Thin sections of the tumour cells showed junctional complexes (tight junctions and intermediate junctions) at the luminal aspect of the lateral cell membranes and desmosomes below them. Freeze-fracture replicas showed well-developed tight junctions with strands arranged in parallel or polygonal patterns. The junctions were continuous 'zonula occludens' type, usually three or more strands deep, with focal proliferation in some areas. The granules in the tumour cells tended to be larger than those of normal human Clara cells, although they were morphologically similar. There was no evidence of secretion of granules from the tumour cells. The relationships between tumour differentiation and growth pattern, and junctional development are discussed.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1988

Prevention of disuse muscle atrophy by means of electrical stimulation: maintenance of protein synthesis.

The effect of percutaneous electrical stimulation in preventing immobilisation-induced muscle atrophy was determined from measurements of quadriceps mass, composition, and rate of protein synthesis in seven men who had a fracture of one tibia immobilised in a long-leg cast for 6 weeks. These features were compared with those of fourteen men with similar injuries who did not use an electrical stimulator. In men who did not use the stimulator, quadriceps cross-sectional area (CSA) at midthigh, measured by ultrasonography, fell by a mean (SD) 17 (10)% and the rate of muscle protein synthesis was 23 (10)% lower on the immobilised than on the control side (0.037 [0.016] vs 0.048 [0.02]%/h). In contrast, in those who used the stimulator, quadriceps CSA (55.5 [7.3]) cm2 control leg, 50.9 [9.0] cm2 immobilised leg) and the rate of muscle protein synthesis (0.053 [0.009] %/h control leg, 0.059 [0.012] %/h immobilised leg) were similar on the two sides. The results suggest that brief periods of low-voltage percutaneous electrical stimulation will reduce quadriceps atrophy secondary to knee immobilisation, and that the mechanism includes prevention of the fall in muscle protein synthesis that usually occurs on immobilisation.

Adolescent↗