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Biomedical subjects

R Long

Publications and source records attributed to R Long.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Separation of sperm through a 12-layer percoll column decreases the percentage of sperm staining with quinacrine.

Previous methods of enriching sperm with a higher percentage of Y-bearing sperm have been questioned because the claims that Y enrichment was present were based on quinacrine staining of the Y chromosome, and the enrichment was not confirmed by polymerase chain reaction (PCR) or fluorescent in situ hybridization (FISH) techniques. A technique was evaluated that theoretically could increase the percentage of X-bearing sperm by isolating a fraction of the "heaviest" sperm by passing them through 12 layers of discontinuous Percoll gradient. Initially 12 specimens were checked both before and then after separation with 12 layers of Percoll for percentage of Y sperm. The median for baseline Y percentage was 49% and after processing the percentage of Y dropped to 10%. An additional 19 specimens were checked after separation only. The median was 19%. The sample with the lowest preseparation % of quinacrine staining sperm was 45% and the highest was 54%. After 12-layer Percoll, the lowest percentage was 3% and the highest was 24%. There have been claims that quinacrine staining can falsely increase apparent Y-bearing sperm enrichment following certain separation procedures, e.g.. albumin separation, by nonspecific staining of autosomal chromosomes. If anything, then, it should falsely decrease X-bearing sperm enrichment. Thus, 12-layer Percoll separation may actually enrich for X-bearing sperm or possibly this procedure somehow nonspecifically inhibits the ability of quinacrine to stain the Y chromosome.

Cell Separation↗
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Treatment of sperm with subnormal host scores with chymotrypsin/viable pregnancy after IUI.

Men with low hypoosmotic swelling test (HOST) scores (<50%) rarely achieve a pregnancy with intercourse or conventional intrauterine insemination (IUI) or even IVF. The defect seems to be related to a toxic factor attached to the sperm that can be transferred to the zona pellucida, which ultimately interferes with implantation. A small case series showed optimistic pregnancy outcome with treatment of the sperm with low HOST scores with chymotrypsin. However, the live pregnancy rate in 90 subsequent IUI cycles in men whose low HOST scores were improved by chymotrypsin was only 3.3%. IVF with ICSI remains the only highly effective treatment of this disorder.

Chymotrypsin↗
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Renin-angiotensin-aldosterone system, electrolyte homeostasis and blood pressure in alloxan diabetes.

The effect of a chronic glucose osmotic diuresis on electrolyte homeostasis was evaluated in alloxan diabetic rats with urine volumes greater than 150 ml/day and glycosuria of 4 to 10 gm/day. Results were compared with control rats for periods up to 84 days. Sodium and potassium intake and urinary losses were significantly higher in diabetic animals throughout the study periods. Negative Na balance, however, persisted for only four days, and negative K balance for only 18 days. Blood volumes were elevated probably secondary to the osmotic effect of hyperglycemia (serum glucose greater than 600 mg %). Plasma renin activity decreased progressively, in part because of an early decrease in renin substrate at a time when renin concentration was normal. Despite hyperkalemia, mean plasma aldosterone was not increased compared with that in control rats, suggesting diabetic rats had relative hypoaldosteronism. Although three diabetic rats became hypertensive, no significant difference in mean blood pressure was observed between the groups. The results suggest that diabetic rats have losses of Na and K early in their diabetes, following which mechanisms to conserve Na and K are activated preventing further electrolyte depletion despite continuation of the osmotic diuresis. Decreased renin activity with inadequate stimulation of aldosterone would contribute to K conservation. Maintenance of Na balance must be explained by increased Na intake and other renal Na conserving mechanisms.

Aldosterone↗
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Multidrug-resistant tuberculosis in Alberta and British Columbia, 1989 to 1998.

OBJECTIVE: To describe the extent of the problem of multidrug-resistant tuberculosis (MDR-TB) in Alberta and British Columbia from 1989 to 1998. DESIGN: A retrospective, population-based descriptive study of all notified MDR-TB cases in the context of all notified TB cases, all notified culture-positive TB cases and all notified drug-resistant TB cases. SETTING: Provinces of Alberta and British Columbia, and their TB registries. PATIENTS: All people with TB reported to the TB registries of Alberta and British Columbia between January 1, 1989 and June 30, 1998. MAIN OUTCOME MEASURES: Drug susceptibility testing was performed in all cases of culture-positive TB. Demographic, clinical and laboratory data on all cases of MDR-TB were recorded. RESULTS: Of 4606 notified cases of TB, 3553 (77.1%) were culture positive. Of these, 365 (10.3%) were drug resistant; of the drug-resistant cases, 24 (6.6%) were MDR. Most MDR-TB patients were foreign-born; of the four Canadian-born patients, two were infected while travelling abroad. Although foreign-born patients were significantly more likely to harbour drug-resistant strains, 14.3% versus 4.8%, respectively (P<0.001), among those who were harbouring a drug-resistant strain, the proportion of Canadian-born versus foreign-born patients with an MDR strain was the same (6.7% versus 6. 6%, respectively). From 1994 to 1998 versus 1989 to 1993, the proportion of all drug-resistant strains that were MDR was greater (9.0% versus 4.3%, respectively), but the difference was not statistically significant. Isolates from 16 of the 24 MDR-TB cases had been archived. Each of these was fingerprinted and found to be unique. Most MDR-TB cases (88%) were respiratory. Of those tested for human immunodeficiency virus (n=17), only one was seropositive. MDR-TB was 'acquired' in 67% and 'primary' in 33% of cases. Eight (33%) of the MDR-TB cases received curative courses of treatment, six (25%) are still being treated, and the remainder have either died (five, 21%), transferred out (four, 17%) or become 'chronic' (one, 4%). No secondary case of MDR-TB has been identified in Alberta and British Columbia. CONCLUSIONS: Most MDR-TB in Alberta and British Columbia is imported. The proportion of all drug-resistant cases that are MDR appears to be increasing, but not because of disease acquired from recent contact with MDR-TB in Canada.

Adult↗
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'Pseudo' treatment failure of pulmonary tuberculosis in association with a tuberculoma.

Failure of tuberculosis patients to respond to treatment is usually explained by one or more of five mechanisms: improper drug prescription; patient nonadherence to prescribed therapy; primary or acquired drug resistance; drug malabsorption; and rarely, exogenous reinfection with a drug-resistant isolate. Response to treatment is best measured bacteriologically; two different smear and one culture criteria for failure are widely used. Patients meeting either smear, but not culture, criteria for treatment failure may be said to have 'pseudo' treatment failure. Whether a patient can meet both smear criteria for failure, and not have a mechanism for treatment failure nor meet culture criteria, is unknown. A case of 'pseudo' treatment failure is reported in which both smear criteria for failure were met, but no mechanism for failure was proven to be operative.

Antitubercular Agents↗
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Medical versus surgical treatment of a primary tuberculous pleural peel.

The role and timing of surgical decortication in the management of a primary tuberculous pleural peel remains controversial. The present report describes the case of a young man with an extensive primary tuberculous pleural peel that responded dramatically to medical therapy. A serious attempt at surgical decortication three weeks into antituberculous drug therapy may have removed some compressive aspects of the peel, facilitating lung expansion. However, it had almost no measurable impact on the size of peel and was technically very difficult. Response to treatment was measured anatomically (computed tomography scans) and physiologically (pulmonary function tests).

Adult↗
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Effect of time interval between ejaculations on semen parameters.

The suggested abstinence period prior to performing a semen analysis has been 2-5 days. If one allows too long of an interval between ejaculates, motility will decrease significantly. This study was designed to evaluate whether any of the semen parameters change with increasing intervals of time between ejaculates and, if so, what parameters are involved. A derived calculation total-live sperm count (product of count/milliliter x volume x percent motility) was significantly lower at 3 days than at 7-, 10-, and 14-day intervals. Sperm count and motility showed a significant decrease at 14 days as compared to 7 days but not to 3 days. There were no significant differences between motility, the hypoosmotic swelling test, velocity, linearity, motile density, or morphology (with strict criteria). The ideal abstinence interval is between 7 and 10 days not 2-3 days, and motility does not appear to significantly decrease with a long interval between ejaculates.

Analysis of Variance↗
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Detrimental effects of cryopreservation on the structural and functional integrity of the sperm membrane.

Many centers have been disappointed with the pregnancy rate following the insemination of cryopreserved-thawed sperm, despite the maintenance of an adequate motile density. The possibility exists that damage to the sperm membrane might occur despite preservation of other semen parameters. Simple measurements of structural integrity (viability) and functional integrity (hypoosmotic swelling test) were performed on thawed specimens. In each instance, both the viability and HOS scores were less than the critical 50% level. Specimens from three different commercial centers had very poor HOS and viability scores from two of the centers, and, though the scores were generally greater than or equal to 50% from the third center, this was achieved by eliminating 11 of 12 donors. Reducing the glycerol concentration from 12 to 7% and switching from Nunc vials to plastic embryo straws did not improve the poor sperm membrane tests. The possibility exists that if modification of the cryopreservation technique leads to improved HOS and viability scores, perhaps improved pregnancy results will be realized.

Cell Membrane↗
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Effect of shortened exposure time to the critical period for ice crystal formation on subsequent post-thaw semen parameters from cryopreserved sperm.

Cryopreservation of human sperm using present methods leads to a reduced fertility potential of the specimen. In many instances this prevents the successful fertilization of the female partner from the frozen-thawed specimens of males whose semen has been cryopreserved prior to surgery, chemo-therapy, or even vasectomy. Furthermore, even though some donor specimens can be successfully used for achieving pregnancies, one needs to place the sperm intrauterine to approach the same pregnancy rates as those of fresh intracervical insemination. The main mechanism considered for sperm damage by cryopreservation is ice crystal formation. The most critical time for forming ice crystals is from 0 to -10 degrees C. In the present study the effect of a modified rapid cryopreservation technique with reduction of exposure time to the 0 to -10 degrees C temperature range was compared to standard freezing procedures on subsequent semen parameters. Though no significant differences were found on post-thaw motile densities or hypoosmotic swelling test scores, a new, equally effective, but more rapid technique for cryopreservation is reported.

Cryopreservation↗
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NHI? Maybe in the 94th.

Explore the source record for details and available documents.

National Health Insurance, United States↗
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Efficacy of intrauterine insemination without ovarian hyperstimulation for male or cervical factor in women aged 40 or over.

The efficacy of intrauterine insemination (IUI) for male or cervical factor by age of female partner was determined in a retrospective analysis. Patients who underwent IUI therapy for cervical and/or male factor (n = 281) were classified by age at first IUI cycle: <40 years (n = 232), > or =40 years (n = 49). The indication for IUI was cervical factor if a postcoital test failed to show sperm with good forward progression at time of mature follicle; male factor was diagnosed if the semen analysis demonstrated either low count, low motility, antisperm antibodies, or subnormal hypoosmotic swelling test. Intrauterine insemination was performed in either natural cycles or following ovarian stimulation for the treatment of anovulation or follicular maturation defects. Cumulative probability of ongoing pregnancy (viable at end of first trimester) following 3 cycles of IUI was evaluated. Cumulative probability of ongoing pregnancy following 3 cycles of IUI was 28.2% for the younger group and 0.0% for the older group. The age groups did not differ in terms of infertility history, use of ovarian stimulation, or baseline semen parameters. Thus, the treatment of male and/or cervical factor by IUI is ineffective for women > or =40 years.

Adult↗
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Drug resistance study of Mycobacterium tuberculosis in Canada, February 1, 1993 to January 31, 1994.

OBJECTIVE: To estimate the prevalence of resistance of Mycobacterium tuberculosis to first-line antituberculosis drugs in Canada. METHODS: M. tuberculosis isolates from one third of all culture-positive tuberculosis (TB) cases diagnosed between February 1, 1993 to January 31, 1994 in Canada were collected prospectively. Proportion of drug-resistant isolates and the factors related to drug resistance were measured. RESULTS: Of 458 study cases, 40 (8.7%) had resistance to at least one first-line antituberculosis drug, of which 5.9% had mono-resistance, 0.7% had multidrug-resistance(MDR-TB)--i.e., resistance to at least isoniazid and rifampin--and 2.2% had other patterns. The overall prevalence of resistance among the foreign-born cases was 10.6% with the highest level among those who resided in Canada for less than four years (15.5%). CONCLUSIONS: Canada has a relatively low prevalence of antituberculosis drug resistance and a very low prevalence of MDR-TB. Some new immigrants to Canada may be at higher risk for drug resistance and their initial treatment needs to be tailored accordingly.

Adolescent↗