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Biomedical subjects

C Foster

Publications and source records attributed to C Foster.

At least 91 records · Page 5Linked to original sources
PubMed1995

Factors influencing the outcome of in-vitro fertilization with percutaneous aspirated epididymal spermatozoa and intracytoplasmic sperm injection in azoospermic men.

In-vitro fertilization (IVF) by intracytoplasmic sperm injection (ICSI) with spermatozoa retrieved by percutaneous epididymal sperm aspiration (PESA) is a novel, simple and effective treatment for azoospermic men. In all, 38 azoospermic men had an IVF/PESA/ICSI cycle. A total of 42 cycles were performed. The aetiology of azoospermia was classified as failed vasectomy reversal (12 patients/16 cycles), inflammatory obstruction (five patients/five cycles), partial testicular failure (five patients/five cycles) and bilateral congenital absence of vas (16 patients/16 cycles). Adequate sperm preparations for ICSI were obtained from 38 of the 42 treatment cycles (90%). The mean fertilization rate was 32.7%, and fertilization occurred in 35 cycles (92.0%). Embryo transfer was performed in 13 out of 14 cycles (93%) in men with a failed vasectomy reversal, four out of five cycles in men with an inflammatory obstruction (80%), four out of four cycles in men with a partial testicular failure (100%), and 14 out of 15 cycles in men with a bilateral congenital absence of vas (93%). The overall pregnancy rate per two or three embryos transferred was 28.6 and 26.3% per treatment cycle respectively. The sperm parameters of the final pooled sperm aspirate preparations varied widely among the four aetiological groups. These parameters were of no value in predicting the fertilization or pregnancy rates (P > 0.05), and neither was the embryo cleavage rate.

Cytoplasm↗
PubMed1995

Titration of HPV-11 infectivity and antibody neutralization can be measured in vitro.

Human papillomavirus type 11 (HPV-11), produced from the athymic mouse xenograft system, was shown to infect cultured neonatal human foreskin keratinocytes and the HaCaT keratinocyte cell line in vitro. Infection was documented by the appearance of HPV-11-specific spliced mRNA, detected by reverse transcriptase-polymerase chain reaction. Purified HPV-11 virions at concentrations of approximately 10(7) particles/ml could successfully evoke infection in this system. Infection was completely abrogated by preincubation of the HPV-11 inoculum with mouse anti-HPV-11 monoclonal antibodies, experimentally immunized animal sera, or sera of human patients with HPV infection. Concurrent detection of cellular mRNA for the beta-actin gene, also by reverse transcriptase-polymerase chain reaction, provided an internal control confirming RNA recovery and successful reverse transcriptase-polymerase chain reaction. Using this approach, it was possible to determine semiquantitative titers for test solutions of HPV-11-neutralizing antibodies. The in vitro system for HPV-11 infectivity and neutralization may be useful in the study of the immune response to HPV-11 infection or immunization in patients.

Actins↗
PubMed1995

Simplified sperm retrieval and intracytoplasmic sperm injection in patients with azoospermia.

OBJECTIVE: To evaluate the rate of recovery of spermatozoa from the epididymis using a percutaneous aspiration technique and to assess the fertilization rate following intracytoplasmic sperm injection (ICSI). PATIENTS AND METHODS: Forty-two patients with azoospermia underwent a total of 46 treatment cycles of in vitro fertilization (IVF) and ICSI. The sperm used for ICSI was retrieved percutaneously by fine-needle aspiration and syringe suction (percutaneous epididymal sperm aspiration, PESA) from the epididymis in 28 patients (mean age 34.9 years), over 32 cycles. Six patients underwent microsurgical sperm aspiration (MESA) and in the remaining eight patients, neither percutaneous aspiration nor MESA yielded suitable sperm and spermatozoa extracted from testicular biopsy were used. RESULTS: A total of 362 oocytes were collected and of those, 286 (79%) were subjected to ICSI. Of the injected oocytes, 49 (17.2%) were damaged, 138 (48.3%) achieved normal fertilization and, of those, 112 (81.2%) cleaved. A total of 67 embryos were transferred and 18 more were suitable for cryopreservation. Of the 25 cycles with embryo transfer, eight resulted in a pregnancy and of these, one miscarried. The pregnancy rate was 25% per cycle and 32% per embryo transfer. The implantation rate was 12%. CONCLUSIONS: This extensive series of PESA/ICSI cycles indicates that PESA can be used successfully to retrieve spermatozoa in patients with azoospermia. The technique is simple, cost-effective and is associated with fewer complications compared to an open microsurgical procedure.

Adult↗
PubMed1995

Holmium-YAG laser for gall stone fragmentation: an endoscopic tool.

A systematic review of the 2.1 mu holmium-YAG laser for gall stone lithotripsy was undertaken. This infrared laser, which can be used endoscopically and percutaneously, has safety advantages over other lasers and has potential as a general purpose vascular and surgical tool. Twenty nine gall stones (mean mass 1.3 g) were fragmented in vitro using pulse energies of 114 to 159 mJ/pulse at 5 Hz with a 0.6 mm fibre, while being held in an endoscopy basket. All stones were successfully fragmented, requiring an average of 566 pulses with a 5 Hz pulse repetition frequency. The number of pulses required increased with gall stone size and mass (p < 0.01), and decreased with both pulse energy (p < 0.01) and operator experience (p < 0.05). The biochemical content of the stone did not significantly affect the number of pulses needed. The potential hazard of the laser to the biliary endothelium was investigated. At the pulse energies used, five pulses at close contact penetrated into the serosa of fresh gall bladder wall. No damage was seen when two pulses were fired. This laser shows considerable promise in gall stone lithotripsy. Until further safety data are available, however, its use with endoscopic vision is advised.

Cholelithiasis↗
PubMed1995

Enhanced nitric oxide synthase activity in portal hypertensive rabbits.

Portal hypertension (PHT) is characterized by splanchnic hyperemia caused by a reduction in mesenteric vascular resistance. Mediators of this hyperemia include nitric oxide (NO). This is based on several reports indicating a marked splanchnic hyporesponsiveness in PHT to vaso-constrictor stimuli, both in vitro and in vivo, and a subsequent reversal using specific inhibitors of NO synthase (NOS). The objective of this study was to determine directly if the generation of NO is altered in PHT vasculature. Thus, we compared NOS activity in the hyperemic vasculature of normal rabbits and rabbits with PHT (after undergoing partial portal vein ligation). Nicotinamide adenine dinucleotide phosphate diaphorase staining indicated the presence of NOS within the vascular endothelium. Ca(2+)-dependent NOS activity was significantly increased (P < .05) in PHT particulate fractions from the superior mesenteric artery and thoracic aorta, but not from the portal vein. There was no change in NOS activity within the cytosolic fractions. Arterial wall cyclic guanosine monophosphate (cGMP) levels and plasma nitrite levels were both significantly increased in PHT. These results show enhanced NOS activity in PHT hyperemic vessels concurrent with increased tissue cGMP levels. We conclude that enhanced NO synthesis contributes to the hyperdynamic circulation of PHT.

Amino Acid Oxidoreductases↗
PubMed1995

Managing sacral pressure ulcers with hydrocolloid dressings: results of a controlled, clinical study.

One-hundred and three patients with Stage II and III sacral pressure ulcers were enrolled in a prospective, controlled, multi-center clinical study to evaluate and compare dressing performance, safety and efficacy. Fifty-two patients were randomized to treatment with a triangle-shaped hydrocolloid border dressing and 51 patients were randomized to a different, oval shape, hydrocolloid dressing. The majority of patients (70 percent) utilized a pressure reducing mattress or bed. Most ulcers were Stage II, had existed for < 1 month and exhibited no change utilizing previous treatments. Patients and wounds were similarly distributed among treatment groups. Patients in the oval dressing group were more likely to exhibit a product related adverse reaction resulting in discontinuation of treatment as compared to patients treated with the triangle border dressing (p = 0.057, Fisher's Exact Test). Wear time was longest for wounds dressed with the triangle dressing applied point down. Incontinence reduced the interval between dressing changes in both groups. Healing was more likely to occur in wounds dressed with the triangle border dressing. These ulcers showed a greater reduction in ulcer width as compared to wounds dressed with the oval dressing (p < 0.03, Fisher's Exact Test).

Aged↗
PubMed1995

The bloodless lactate profile.

The blood lactate profile (HLa-P) is an accepted method of evaluating athletes and providing a basis for the prescription of training intensity. For both logistic and public health reasons HLa-P is less than optimal. In this study we evaluate the relative velocity or the %HR-max, obtained during a training session, as alternatives to HLa-P. Competitive speed skaters (N = 20) performed HLa-P consisting of 5.2000 m/400 m at incremental velocities ranging from very slow to maximal (time = 3.0-5.0 min). Blood lactate measured during a 60-s interval following each repetition was used to construct HLa-P and to predict the velocity associated with steady state (HLa = 4.0-6.5 mmol.l-1). Relative velocity was calculated relative to the velocity of the maximal trial. A plot of relative velocity and %HRmax vs HLa demonstrated that HLa = 4.0-6.5 mmol.l-1 occurred at a relative velocity of 78-88% (R2 = 0.807) and at 84-92 %HRmax (R2 = 0.748). In a separate training session the relative velocity and %HRmax models were cross validated by having the subjects skate 9.2000 m/400 m at constant velocity. HLa changes during the training session defined the presence/absence of steady state (delta HLa < 1.0 mM from trial 3 to 9). Comparing the velocity during the training session vs the velocity predicted from HLa-P, relative velocity model and %HRmax model allowed a test of the accuracy of bloodless means of defining steady state. HLa-P correctly predicted 81% of training session HLa responses, the relative velocity model correctly predicted 78%, and the %HRmax model correctly predicted 68%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Insulin resistance and not hyperinsulinaemia determines erythrocyte Na+/Li+ countertransport in non-insulin-dependent diabetes mellitus.

Insulin resistance and increased erythrocyte Na+/Li+ countertransport activity are well documented in subjects with essential hypertension, raising the question whether compensatory hyperinsulinaemia might be responsible for activating Na+/Li+ countertransport. We measured Na+/Li+ countertransport in 63 non-nephropathic non-insulin-dependent diabetic subjects (36 hypertensive, 27 normotensive), finding no correlation with fasting levels of insulin (r = 0.074, P = 0.28), despite using a sensitive and specific insulin assay. In contrast, in 33 of the subjects in whom insulin sensitivity was measured, Na+/Li+ countertransport correlated significantly with the whole body glucose clearance rate (r = -0.37, P = 0.036). It is concluded that increased Na+/Li+ countertransport may be a cellular marker for insulin resistance, but that hyperinsulinaemia is not likely to be the factor which mediates this relation.

Aged↗
PubMed1995

Left ventricular ejection fraction during incremental and steady state exercise.

Despite extensive study of left ventricular (LV) function during incremental exercise (INC), there is little known about LV function during steady state exercise typical of that used during exercise training. In this study we evaluated LV ejection fraction (LVEF) during upright cycle ergometer exercise using first-pass radionuclide angiography (RNA). Healthy volunteers (N = 10) were studied during both INC and steady state. INC studies were performed at rest, at the ventilatory threshold (VT), and at maximal exercise. During steady state studies were performed after 10, 20, and 30 min of exercise at VT. During INC LVEF increased from rest (61% +/- 5%) to exercise at the VT (73% +/- 5%). There was no further change in LVEF at maximal exercise (73% +/- 5%). During steady state, LVEF increased from rest (61% +/- 5%), to exercise at VT (73% +/- 5%), with further increases after 20 (78% +/- 6%) and 30 (79% +/- 3%) min of exercise. The results suggest that LVEF is nearly maximal during submaximal exercise at VT. During steady state LVEF continues to increase with continuation of steady state exercise.

Adult↗
PubMed1994

Expression of hepatocyte growth factor mRNA, and c-met mRNA (hepatocyte growth factor receptor) in human liver tumours.

We have quantified mRNA for the hepatocyte growth factor and its putative receptor the c-met proto-oncogene protein product, in a series of human primary and secondary liver tumours and adjacent non-neoplastic liver. In all hepatocellular cancers, hepatocyte growth factor 6 kb mRNA expression was less (mean 23.93% +/- 6.33% S.E.M. n = 7) in the tumours than in the adjacent normal liver. Both relative over- and under-expression of c-met transcripts were found in tumour tissue compared to non-neoplastic liver. Thus hepatocellular cancer tissue does not over-express mRNA for hepatocyte growth factor, though this growth factor might play a role in hyperproliferative states leading to liver cancer.

Adenoma↗
PubMed1994

A simplified approach to estimating the maximal lactate steady state.

The exercise intensity associated with an elevated but stable blood lactate (HLa) concentration during constant load work (the maximal steady state, MSS) has received attention as a candidate for the "optimal" exercise intensity for endurance training. Identification of MSS ordinarily demands direct measurement of HLa or respiratory metabolism. The purpose of this study was to test the ability of heart rate (HR) to identify MSS during steady state exercise, similar to that used in conventional exercise prescription. Trained runners (n = 9) and cyclists (n = 12) performed incremental and steady state exercise. MSS was defined as the highest intensity in which blood lactate concentration increased < 1.0 mM from minutes 10 to 30. The next higher intensity workbout completed was defined as > MSS. HR models related to the presence or absence of steady state conditions were developed from the upper 95% confidence interval of MSS and the lower 95% confidence interval of > MSS. Cross validation of the model to predict MSS was performed using 21 running and 45 cycling exercise bouts in a separate group. Using the MSS upper 95% confidence interval model 84% and 76% of workbouts were correctly predicted in cyclists and runners, respectively. Using the > MSS lower 95% confidence interval model, 76% and 81% of workbouts were correctly predicted in cyclists and runners, respectively. Prediction errors tended to incorrectly predict non-steady state conditions when steady state had occurred (16/26) (62%). We conclude that use of these simple HR models may predict MSS with sufficient accuracy to be useful when direct HLa measurement is not available.

Adult↗
PubMed1994

Successive time courses of strength development and steroid hormone responses to heavy-resistance training.

Subjects (5 males, 5 females) performed heavy-resistance exercise at a constant stimulus 3 days/wk for 8 wk. Work rates were then increased to higher but constant levels for an additional 8 wk. Half times of the first training period were 14 and 10 days for the bench press and parallel squat, respectively. The second time course resulted in only one-third of the overall magnitude of strength increases for both exercises as the first, and the kinetics were slower in the parallel squat but similar in the bench press (half time 13 days). Skeletal muscle fiber area was significantly increased (19%) in fast-twitch fibers by the end of the second training period. Postexercise elevations in serum cortisol and prolactin were seen only in the male subjects. Because the males trained at considerably higher work loads than the females, these results imply that absolute amounts of resistance may be an essential requirement for inducing certain hormonal responses. Serum cortisol levels in males after exercise were blunted by the 5th wk of the first time course. For serum testosterone, neither resting nor higher post-exercise concentrations were different at any point of the training periods for either sex. We conclude that the strength time course results are not inconsistent with current thought on factors contributing to strength accumulation. The absence of a specific serum androgenic response with strength development may be related to the fact that the constant exercise stimulus is not conducive to establishing clear-cut hormone-strength relationships.

Adult↗
PubMed1994

Insulin resistance, insulin, proinsulin, and ambulatory blood pressure in type II diabetes.

Both insulin resistance and insulin concentrations correlate with blood pressure in nondiabetic subjects, but there is no consensus on these relations in subjects with non-insulin-dependent diabetes, perhaps because of the use of nonspecific insulin assays and clinic blood pressure measurement. Therefore, we have investigated the relation between ambulatory blood pressure, insulin sensitivity (measured by an insulin sensitivity test), and levels of insulin and its principal precursors, measured by specific assays, in 24 subjects with non-insulin-dependent diabetes. Insulin sensitivity (glucose metabolic clearance rate) correlated strongly with mean 24-hour ambulatory systolic blood pressure (r = -.650, P < .001). In contrast, there was no relation between this blood pressure index and fasting levels of insulin (r = .096, P = NS) or all insulin-like molecules (r = .077, P = NS). Dichotomized on 24-hour ambulatory systolic blood pressure levels, the hypertensive group was more insulin resistant than the normotensive group (metabolic clearance rate, 3.6 [0.7] versus 6.5 [3.0] mL.kg-1.min-1, P = .006), whereas there was no difference in insulin or proinsulin concentrations among the groups. In multiple regression analysis, insulin sensitivity was the major determinant of blood pressure. We conclude that in subjects with non-insulin-dependent diabetes mellitus, blood pressure is related to insulin sensitivity but not to fasting levels of insulin, suggesting that hyperinsulinemia is probably not the mediator of this relation.

Ambulatory Care↗
PubMed1994

Accuracy of the Omron HEM 706 portable monitor for home measurement of blood pressure.

A reliable, well-validated home blood pressure (BP) self-measurement device could have an important role in the management of hypertension by the early identification of 'white coat' hypertensives. Under rigorous assessment such devices have not performed well in the estimation of DBP, particularly in the hypertensive range. We assessed the Omron HEM 706 device (oscillometric) for home measurement of BP according to the standards set out by the British Hypertension Society protocol and the Association for the Advancement of Medical Instrumentation (AAMI). The device was compared with simultaneous measurements made by two 'blinded' observers using a standard mercury sphygmomanometer in the same arm in 85 subjects aged 17-76 years with a wide range of BPs. The device was satisfactory over the whole BP range (SBP 89-188 mmHg, DBP 44-118 mmHg), with a B grading for SBP and a C grading for DBP (British Hypertension Society protocol) and a PASS for both SBP and DBP (AAMI). For the diastolic hypertensive range 90-120 mmHg, where most clinical decisions are made, the device scored a B grade for SBP and an A grade for DBP, with a PASS for both SBP and DBP. We conclude the Omron HEM 706 device for home BP measurement is highly satisfactory, particularly in the mild to moderate hypertension range, and is suitable for clinical use.

Adolescent↗
PubMed1994

Increased blood pressure variability during 24h blood pressure monitoring as an early sign of autonomic dysfunction in non-insulin-dependent diabetics.

To evaluate the presence of early autonomic dysfunction in non-insulin-dependent diabetics we examined 24h control of blood pressure (1/4 hourly readings day and 1/2 hourly at night, using TM 2420) in 20 non-insulin-dependent diabetics, controlled only on diet or oral hypoglycaemics and 20 age/sex/BP matched non-diabetics selected from a random population survey. The two groups were aged 52 +/- 9 years and 53 +/- 8 years, respectively. Both groups included normotensives and mild hypertensives in equal numbers but none was on antihypertensive treatment. The groups were well matched for daytime systolic blood pressure (SBP; 132.2 +/- 11.4 vs. 131.2 +/- 10.3) and diastolic blood pressure (DBP; 82.1 +/- 8.3 vs. 81.1 +/- 7.0). The diabetics had a significantly greater heart rate (HR) both during the day (79.6 +/- 9.5 vs. 72.3 +/- 8.8: P = 0.015) and during sleep (67.7 +/- 6.8 vs. 62.5 +/- 8.9). There was increased BP variability in the diabetics during the day (standard deviation of SBP; 16.9 +/- 6.2 vs. 13.3 +/- 4.7: P < 0.05) but the difference for DBP variability was not significant. The day-night difference for SBP, DBP, HR and HR variability was the same in both groups. We conclude that in these patients there was evidence for an alteration in BP variability (which may reflect baroreflex insensitivity) at a stage where there was no alteration in day-night rhythms of BP or HR. The increased HR both at day and night may also reflect baroreflex dysfunction and/or sympathovagal imbalance.(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Nervous System↗