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Biomedical subjects

K R Baker

Publications and source records attributed to K R Baker.

At least 19 recordsLinked to original sources
PubMed2002

Abnormal optical waveform profiles in coagulation assays from patients with antiphospholipid antibodies.

Transmittance waveforms are the optical data generated during clot formation on photo-optical coagulation analyzers and are used to define specific events of the clotting reactions. Thus, a prothrombin time (PT) or an activated partial thromboplastin time (aPTT) can be divided into a pre-coagulation phase, a coagulation phase, and a post-coagulation phase. These phases are further characterized by parameters that define the timing, the rate, the 'slope', and the magnitude of the signal change of the reactions. We investigated the transmittance waveform parameters obtained during PT and aPTT of patients with antiphospholipid antibodies (APLA) who were or were not taking warfarin, normal donors, and non-APLA patients taking warfarin. An abnormal deflection in the pre-coagulation phase of the PT (called slope 1) was observed in 61.5% of the patients with APLA, in contrast to 5.9% of non-APLA patients taking warfarin (P= 0.0015). The presence of an abnormal PT slope 1 was reagent specific and was inversely correlated with the anticardiolipin antibody immunoglobulin G (IgG) level, which suggests that the abnormal PT slope 1 may reflect interactions between patient IgG and components from the thromboplastin, possibly phospholipids. The abnormal PT slope 1 values may be of diagnostic utility in the identification of patients with antiphospholipid syndromes.

Antibodies, Anticardiolipin↗
PubMed2001

The efficacy of home based progressive strength training in older adults with knee osteoarthritis: a randomized controlled trial.

OBJECTIVE: To test the effects of a high intensity home-based progressive strength training program on the clinical signs and symptoms of osteoarthritis (OA) of the knee. METHODS: Forty-six community dwelling patients, aged 55 years or older with knee pain and radiographic evidence of knee OA, were randomized to a 4 month home based progressive strength training program or a nutrition education program (attention control). Thirty-eight patients completed the trial with an adherence of 84% to the intervention and 65% to the attention control. The primary outcome was the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index pain and physical function subscales. Secondary outcomes included clinical knee examination, muscle strength, physical performance measures, and questionnaires to measure quality of life variables. RESULTS: Patients in the strength training group who completed the trial had a 71% improvement in knee extension strength in the leg reported as most painful versus a 3% improvement in the control group (p < 0.01). In a modified intent to treat analysis, self-reported pain improved by 36% and physical function by 38% in the strength training group versus 11 and 21%, respectively, in the control group (p = 0.01 for between group comparison). In addition, those patients in the strength training group who completed the trial had a 43% mean reduction in pain (p = 0.01 vs controls), a 44% mean improvement in self-reported physical function (p < 0.01 vs controls), and improvements in physical performance, quality of life, and self-efficacy when compared to the control group. CONCLUSION: High intensity, home based strength training can produce substantial improvements in strength, pain, physical function and quality of life in patients with knee OA.

Aged↗
PubMed2000

Donor cell leukemia: report of a case occurring 11 years after allogeneic bone marrow transplantation and review of the literature.

We report the case of a man with chronic myelocytic leukemia (CML) and a 46,XY,t(5;9;22) karyotype who developed acute myelocytic leukemia (AML) with a 45,X,t(8;21) karyotype 11 years after bone marrow transplantation (BMT) from his HLA-matched sister. Fluorescent in situ hybridization (FISH) studies and molecular analysis using short tandem repeat (STR) sequences proved the new leukemia to be of donor cell origin. Donor cell leukemia (DCL) after BMT is rare. Our review of the literature found 15 cases following BMT for leukemia and 2 cases after BMT for benign hematological disorders. In fewer than half the reported cases were molecular studies available to confirm the cytogenetic evidence for DCL, and the longest previously reported interval between BMT and DCL was 6 years.

Adult↗
PubMed2000

Thrombotic thrombocytopenic purpura and the hemolytic-uremic syndrome.

Large and unusually large von Willebrand factor (vWf) multimers may be responsible for systemic platelet aggregation in thrombotic thrombocytopenic purpura (TTP). This possibility is supported by studies that show deficient vWf-cleaving metalloproteinase and increased platelet-vWf binding during TTP episodes. In acute idiopathic TTP, decreased vWf metalloproteinase is the result of autoantibodies against the enzyme. In familial and acquired hemolytic-uremic syndrome, vWf-cleaving metalloproteinase activity is normal. A deficiency or defect in factor H, which normally dampens the activation of C3 via the alternative complement pathway, has been seen in some patients with familial hemolytic-uremic syndrome. Ticlopidine therapy is an important risk factor for TTP.

Anti-Bacterial Agents↗
PubMed1996

Seated versus standing cycling in competitive road cyclists: uphill climbing and maximal oxygen uptake.

Seven competitive road cyclists (M +/- SE = 23.7 +/- 1.5 yr, 70.5 +/- 1.7 kg) participated to determine the effects of cycling body position on physiological responses during uphill cycling and maximal oxygen uptake (VO2max). There was no significant difference in VO2max between seated and standing positions on a cycle ergometer (66.4 +/- 1.6 vs. 66.4 +/- 1.7 ml . kg-1 . min-1). When the subjects rode their own bicycle on a treadmill, oxygen uptake and heart rate were significantly (p < 0.05) higher during standing when subjects bicycled at 20.0 km . h-1 (4% grade), but no difference was observed when riding at 12.3 km . h-1 (10% grade). Leg RPE was significantly (p < 0.05) lower for standing position up a 10% grade. The results suggest that the standing position is less economical during moderate hill climbing, but during steep hill climbing, it results in a decreased sensation of effort in the legs.

Adult↗
PubMed1992

Age as a risk factor in major genitourinary surgery.

Surgery for urinary incontinence is often not considered in elderly persons (older than 65 years) because of their age. In this paper the authors examine the effect of age on the success rate and complications of abdominal correction (modified retropubic colpourethropexy with or without other major gynecologic surgery) for genuine stress incontinence. Other than age, length of hospital stay and some urodynamic values there were no statistically significant differences in success and complication rates between the elderly and younger patients. The authors conclude that in properly selected elderly patients with genuine stress incontinence, retropubic colpourethropexy is as safe and effective as in younger patients.

Adult↗
PubMed1991

Partial characterization of a unique mitogenic activity secreted by rat Sertoli cells.

Sertoli cell conditioned medium (SCCM) contains a potent mitogen, Sertoli cell secreted growth factor (SCSGF). A431 cells, derived from a human epidermoid carcinoma have provided an excellent model cell line for the study of this apparently unique activity secreted by rat Sertoli cells in vitro. Previously, it was shown that SCCM contained an epidermal growth factor (EGF)-like activity which was thought to be the mitogen for A431 cells. The present study showed that these two factors are distinct entities. The secretion of the EGF-like activity decreased with increasing number of culture days, while that of SCSGF and of another Sertoli cell specific protein, transferrin remained constant. The addition of SCCM stimulated whereas 2.5 ng/ml EGF inhibited the A431 cell growth. The proliferative response of A431 cells to a wide variety of growth factors and known Sertoli cell secretions was investigated. SCSGF was the only growth factor of known Sertoli cell secretions tested (transforming growth factors (TGF alpha, TGF beta), EGF, bombesin, fibroblast growth factor (FGF), platelet derived growth factor (PDGF), insulin-like growth factors 1 and 2 (IGF-1 and IGF-2), prostaglandins E-1 and E-2, insulin, transferrin and lactate) which stimulated A431 cell proliferation. SCSGF was mitogenic for A431 cells even in the presence of serum in the culture medium. The partially purified SCSGF was heat- and acid-stable, protease-sensitive with a molecular weight of 14,000. It did not bind to heparin or concanavalin A-Sepharose. The secretion of a mitogenic activity by the Sertoli cell which is different from other previously identified growth factors and which coincides with active spermatogenesis could have important implications in the regulation of spermatogenesis.

Animals↗
PubMed1991

Effectiveness of antibiotic prophylaxis in preventing bacteriuria after multichannel urodynamic investigations: a blind, randomized study in 124 female patients.

One hundred twenty-four women with chronic, persistent lower urinary tract symptoms who had been scheduled for elective urodynamic investigations at Mount Sinai's Urodynamic Investigative Unit were divided into two blind, randomized groups, receiving either a placebo or prophylactic antibiotic. At the time of urodynamic testing, the rate of unsuspected urinary tract infection was 8.1%. There was no statistically significant decrease in postinstrumentation infection rate in the group who received prophylactic antibiotics. We conclude that, given in the fashion described in the study, prophylactic antibiotics are not effective in preventing urinary tract infections caused by urodynamic testing.

Adult↗
PubMed1990

Colposacropexy with Prolene mesh.

A retrospective analysis of 59 patients who underwent colposacropexy (CSP) using Prolene (polypropylene) mesh is presented. Fifty-eight of the patients had undergone previous surgical treatment, including either vaginal or abdominal hysterectomy. Twenty-two patients underwent CSP alone, 24 had CSP and retropubic urethropexy (RPU), eight had CSP with anterior or posterior repair, or both, and five had CSP and RPU with anterior and posterior repair. The operations were associated with a minimum of intraoperative complications and acceptable postoperative problems. A postoperative questionnaire was sent to the patients with an 89 per cent response rate. None of the patients complained of protrusion from the vagina. It is concluded that, in the hands of experienced surgeons, CSP is a safe, efficacious operative procedure that should remain the procedure of choice for vaginal vault prolapse since it restores the normal vaginal axis, maintains existing vaginal length and provides permanent care.

Female↗
PubMed1988

Cerebral blood flow velocity in term newborn infants: changes associated with ductal flow.

The effects of ductal closure on range-gated pulsed Doppler cerebral blood flow velocity (CBFV) patterns in the internal carotid, anterior cerebral, and middle cerebral arteries were studied in 10 normal term infants (mean birth weight 3302 +/- 294 g (SD) and mean gestational age 39.6 +/- 1.3 weeks). Pulsatility was calculated from flow velocities and used as an estimate of cerebral blood flow (CBF). Ductal closure was associated with a rise in mean blood pressure from 45.0 +/- 4.2 to 51.3 +/- 6.5 mm Hg (P less than 0.05) and a significant decrease in pulsatility in all three vessels (mean = 0.77 +/- 0.07 vs 0.70 +/- 0.05 (P less than 0.02]. Changes in pulsatility were correlated with changes in mean blood pressure (P less than 0.02), providing evidence that systemic blood pressure may influence postnatal cerebral arterial pulsatility indices. We also noted significant differences in the velocity and pulsatility of individual vessels that were independent of blood pressure, suggesting that Doppler flow studies may be useful in describing regional CBF patterns. The temporal association between ductal closure and decreased pulsatility suggests that CBFV patterns reflect ductal shunting in normal term newborn infants. Diastolic runoff and reduced systemic blood pressure in the presence of ductal shunting appear to reduce diastolic flow velocity and increase CBFV pulsatility in normal term infants during the first days of life. Normal mechanisms of cerebral autoregulation compensate for decreased flow with vasodilation; therefore the increased pulsatility associated with ductal shunting may be due to diastolic runoff rather than increased cerebrovascular resistance.

Blood Pressure↗
PubMed1980

Prediction of left ventricular pressure in infants with aortic stenosis.

Peak systolic left ventricular pressure was predicted in five infants with aortic stenosis by use of a wall stress constant, K. K was determined in 10 normal infants according to the formula K = P . Ds/Ws, where P = arterial pressure by Doppler, DS = end-systolic LV dimension, and WS = end-systolic wall thickness. Left ventricular peak systolic pressure was estimated in five infants using the formula P = K. Ws/Ds. Excellent correlation was obtained between measured left ventricular pressure and left ventricular-aortic pressure difference at cardiac catheterisation and echo estimates. Echocardiographic assessment of the severity of aortic stenosis may be applied to infants with good results.

Aortic Valve Stenosis↗