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Biomedical subjects

D C Martin

Publications and source records attributed to D C Martin.

At least 19 recordsLinked to original sources
PubMed1992

A rapid and sensitive cellular enzyme-linked immunoabsorbent assay (CELISA) for the detection and quantitation of antibodies against cell surface determinants. I. A comparison of cell fixation and storage techniques.

A solid phase cellular ELISA was designed and evaluated for the detection of antibodies specific for cell surface determinants. It was hypothesized that certain fixation and freezing procedures would result in stabilization of cell structures for prevention of antigen diffusion and extraction during washing procedures. This would assure assay accuracy and convenient sample management. It was hypothesized that fixation with certain reagents prior to analysis would not alter antigenicity of antibody targeted epitopes. In order to improve the preservation of the cells following cell binding to the solid phase matrix while still retaining antigenicity and morphology, a series of fixatives and storage procedures were screened to determine which were best suited for CELISA. Methanol, washing buffer (WB), Hanks' balanced salt solution (HBSS), and 0.5% formalin in HBSS were examined by comparing their relative cell binding capacity and the subsequent cell morphology. In consideration of all variables, fixation in 0.5% formalin provided the best maintenance of cell antigenicity, morphology, binding, and was associated with consistent results. Cells used immediately after fixation and fixed cells used after storage at -80 degrees C for up to 12 months were compared to determine if long term storage affected antigenicity. Since frozen cells and fresh cells demonstrated statistically identical positive to negative ratios and consistency of antibody binding, it was determined that long term frozen storage of formalin-fixed cells did not adversely affect antibody binding capacity to cell surface determinants.

Animals↗
PubMed1992

Fundus measurements with indirect ophthalmoscopy. An experimental approach.

We examined the factors influencing the accuracy of indirect ophthalmoscopic estimates of choroidal tumor size by studying indirect ophthalmoscope photographs of solid black domes implanted in the suprachoroidal space of postmortem human eyes. Measurements of the indirect ophthalmoscope photographs showed clinically significant differences in the absolute diameter of the visualized fundus, which varied with differences in condensing lens power and width, anteroposterior location of viewed fundus, and axial length of the experimental eye. Linear regression analysis demonstrated that the field of view of each condensing lens varied similarly with axial length and that the majority of variation in field size for each condensing lens was attributable to axial length variation. Equatorial fields of view averaged 11% smaller than posterior fields of view. The accuracy of estimated absolute intraocular dimensions using indirect ophthalmoscopy potentially approaches +/- 5%.

Choroid Neoplasms↗
PubMed1992

Modification of Le Bag ileocolonic pouch with improved results. Review of 17 cases.

The use of detubularized terminal ileum and cecum to construct a highly compliant, low-pressure, continent ileocolonic pouch was first described by Light and Engelman and was termed the "Le Bag." Results were excellent in terms of continence and preservation of renal function; however, nocturnal incontinence persisted in a substantial number of patients. We have modified the original procedure in 17 patients by performing a urethral-cecal anastomosis instead of using a tail of nondetubularized ileum. In addition, in those patients in whom a urethral anastomosis is contraindicated, we have modified the nipple as the continence-providing mechanism. Overall daytime and nighttime continence rate is 94 percent. Of the 13 patients with urethral-cecal anastomoses, only 1 patient requires intermittent catheterization. The remainder are voiding by Valsalva maneuver and with minimal residual urine. Based on our experience with the Le Bag ileocolonic pouch, we believe it is an excellent choice for total bladder replacement or continent diversion--the advantages being the relative ease of construction, minimal long-term complications, and near total urinary continence.

Adolescent↗
PubMed1992

Deep endometriosis: a consequence of infiltration or retraction or possibly adenomyosis externa?

OBJECTIVE: To analyze the incidence and occurrence of subtypes of deep endometriosis. DESIGN: Deep endometriotic lesions (> 5 mm) were retrospectively analyzed, using our data base and slides taken systematically during surgery. SETTING: University Hospital Gasthuisberg (University of Leuven) which is a referral center for infertility and endoscopic surgery. PATIENTS: All women with deep endometriosis (n = 136) were selected from a consecutive series of 1,252 laparoscopies for infertility, pain, or both. INTERVENTIONS AND MAIN OUTCOME MEASUREMENTS: Deep endometriosis was excised by CO2 laser and the depth of infiltration and the pelvic area measured. As part of an ongoing study, most lesions were photographed. RESULTS: Deep endometriosis is suggested to contain three subgroups. Type I is conical shaped and suggested to be formed by infiltration. Type II is deeply located and covered by extensive adhesions and probably formed by retraction. Type III is a spherical nodule with its largest dimension under the peritoneum. Types I, II, and III are found in 4.1%, 0.8%, and 0.9% of women with infertility (n = 759) and in 10.4%, 3.2%, and 3.2% of women with pelvic pain (n = 374). Types I, II, and III are most frequently found in the revised American Fertility Society classes II, III to IV, and I, respectively. CONCLUSIONS: Three subtypes of deep endometriosis can be distinguished. Type III, which is a spherical nodule located in the recto vaginal septum is the most severe and largest lesion. This is, however, easily missed clinically because these lesions are generally scored as revised American Fertility Society class I.

Aging↗
PubMed1992

Time dependency of cognitive recovery with cobalamin replacement: report of a pilot study.

OBJECTIVE: To examine the effects of cobalamin repletion on cognition in elderly subjects with low serum cobalamin and evidence of cognitive dysfunction. DESIGN: Time series data collected in an open trial of parenteral cobalamin therapy. SETTINGS: Outpatient geriatric assessment centers, inpatient geropsychiatry unit, and tertiary care university hospital. PARTICIPANTS: Twenty-two subjects with low serum cobalamin (less than 150 pmol/L) and evidence of cognitive dysfunction were entered consecutively over an 8-month period of time. Eighteen subjects completed the study. INTERVENTIONS: Subjects received 1000 micrograms of cyanocobalamin intramuscularly daily for 1 week, then weekly for 1 month, then monthly thereafter for a minimum of six months. OUTPATIENT MEASURE: The Mattis Dementia Rating Scale (DRS) was administered both before and at least 6 months after full cobalamin replacement therapy. The hypothesis that cognitive improvement was dependent on the duration of cognitive symptoms was formulated a posteriori. RESULTS: After a minimum of 6 months of cobalamin therapy, 11 of 18 patients showed cognitive improvement. There was a striking correlation between duration of cognitive symptoms and response to therapy. Patients symptomatic for less than 12 months gained an average of twenty points on the DRS (paired t test P = 0.0076), whereas patients symptomatic greater than 12 months lost an average of three points (paired t test P = .34). Two patients symptomatic for only 3 months normalized their DRS scores, gaining 31 and 28 points, respectively. CONCLUSION: There may be a time-limited window of opportunity for effective intervention in patients with cognitive dysfunction and low serum cobalamin.

Aged↗
PubMed1992

Coexistence of contractile and relaxant 5-hydroxytryptamine receptors coupled to distinct signaling pathways in intestinal muscle cells: convergence of the pathways on Ca2+ mobilization.

Muscle cells were dispersed separately from circular and longitudinal muscle layers of guinea pig intestine, and 5-hydroxytryptamine (5-HT) receptors were characterized in naive cells and in cells in which one receptor type was preserved by selective receptor protection. In naive cells from both regions, 5-HT caused contraction and stimulated increases in cytosolic free calcium concentration ([Ca2+]i) (3-fold; p < 0.01) and cAMP levels (40-60%; p < 0.01) that were inhibited, respectively, by the 5-HT2 antagonist ketanserin and the 5-HT1p antagonist N-acetyl-5-hydroxytryptophyl 5-hydroxytryptophan amide (5-HTP-DP). In circular muscle cells, where agonist-induced increase in [Ca2+]i is mediated by Ca2+ release from inositol (1,4,5)trisphosphate-sensitive stores, 5-HT caused an increase in inositol (1,4,5)trisphosphate levels that was inhibited by ketanserin. In cells maximally contracted with a non-5-HT agonist (cholecystokinin octapeptide), 5-HT caused relaxation when the contractile effect mediated by 5-HT2 receptors was blocked with ketanserin; relaxation and the concomitant increase in cAMP were inhibited by 5-HTP-DP. The singular contributions of the Ca2+ and cAMP signaling pathways were identified in cells where only one receptor type was preserved. In cells with only 5-HT2 receptors, 5-HT caused contraction and an increase in [Ca2+]i but not in cAMP levels; contraction and the increase in [Ca2+]i were inhibited by ketanserin. Conversely, in cells with only 5-HT1p receptors, 5-HT caused relaxation and an increase in cAMP levels but not in [Ca2+]i; relaxation and the increase in cAMP levels were inhibited by 5-HTP-DP. The two signaling pathways were functionally linked, converging to regulate the level of [Ca2+]i. Thus, the increase in [Ca2+]i was augmented 1) when cAMP production was inhibited by 5-HTP-DP in naive cells or 2) when cAMP production was suppressed in cells where 5-HT1p receptors were inactivated and only 5-HT2 receptors were preserved. The results imply that the increase in cAMP levels mediated by 5-HT1p receptors acted to attenuate the increase in [Ca2+]i mediated by 5-HT2 receptors. We conclude that the response to 5-HT in muscle cells is a compound effect involving activation of two receptor types coupled to distinct signaling pathways that converge on [Ca2+]i as the determinant of mechanical activity.

5-Hydroxytryptophan↗
PubMed1992

Correlation of focal pelvic tenderness with implant dimension and stage of endometriosis.

Reported symptoms in patients with endometriosis have shown poor correlation with the extent of disease at surgery. Recent data have suggested that signs and symptoms may correlate with depth and volume of individual implants. In this study preoperative focal tenderness was correlated with the presence or absence of endometriosis, depth and volume of the endometrial implants and the presence of other pathology. The findings suggest that focal tenderness has limited value in predicting the stage of endometriosis, but is strongly associated with the presence of disease in the cul de sac and uterosacral ligaments. There was also significant association of tenderness with deeper and larger volumes of implants, a finding that may be of clinical significance in the surgical management of endometriosis-associated symptoms and tenderness.

Endometriosis↗
PubMed1992

Ophthalmoscopy versus fundus photographs for detecting and grading diabetic retinopathy.

Reported here is the agreement between three examination methods chosen to detect and grade diabetic retinopathy in 124 subjects with type II (noninsulin-dependent) diabetes mellitus. These three examination methods include ophthalmoscopy (indirect and direct) by a retina specialist, seven standard field fundus photographs read by the same retina specialist, and the same photographs read by a trained photographic grader at the Fundus Photograph Reading Center. For the 59 subjects examined with all three methods, these results indicated fair to good (kappas, 0.69-0.84) agreement between the retina specialist's and trained grader's reading of photographs, fair to good (kappas, 0.58-0.79) agreement between the retina specialist's ophthalmoscopic findings and the specialist's reading of photographs, and fair (kappas, 0.49-0.62) agreement between the retina specialist's ophthalmoscopic findings and the trained grader's reading of fundus photographs. Analysis of the disagreements confirmed earlier reports that ophthalmoscopy misses approximately 50% of eyes with microaneurysms only. Other disagreements resulted from the trained grader's overreading photographs of eyes with lesions simulating diabetic retinopathy. Of the 393 total subjects (diabetic and nondiabetic) in this study, such lesions were seen with ophthalmoscopy in six eyes of six subjects (2.4% of diabetic patients and 1.1% of nondiabetic subjects). The authors believe at least one definite retinal microaneurysm should be present in one eye before establishing the diagnosis of diabetic retinopathy in diabetic patients.

Aged↗
PubMed1992

Blood coagulation, fibrinolytic and inhibitory profiles in renal transplant recipients: comparison of cyclosporine and azathioprine.

Renal transplant recipients treated with cyclosporine (CS) have been reported to be at increased risk of thrombotic complications. The present study was intended to examine the blood coagulation, fibrinolytic, and inhibitory systems in such patients. Eight transplant recipients on maintenance immunosuppression with CS and prednisone were studied. Five transplant recipients maintained on azathioprine (AZA) and prednisone and 32 normal volunteers served as controls. Plasma antigen concentrations and/or activities of various proteins in the above pathways were measured. Both the CS and AZA groups exhibited significant elevations of factor IX activity, von Willebrand factor (vWF), D-dimer, protein C and tissue type plasminogen activator (t-PA) levels when compared with the normal controls. In addition, CS group showed a significant elevation of alpha 2-macroglobulin activity and AZA group showed a significant reduction in factor XII activity when compared with the normal controls. Comparison of data from CS and AZA groups revealed higher factor XII activity and vWF concentration in the former group. In conclusion, transplant recipients treated with long-term cyclosporine and prednisone exhibited significant elevation of plasma vWF, D-dimer and protein C concentrations. In addition, both CS and AZA-treated transplant recipients showed increased plasma concentrations of D-dimer and t-PA. The latter observations suggest in vivo thrombin generation, fibrin formation and degradation.

Adult↗
PubMed1991

Volatile anesthetics and NMDA receptors. Enflurane inhibition of glutamate-stimulated [3H]MK-801 binding and reversal by glycine.

The influence of enflurane, a volatile general anesthetic, on [3H]MK-801 binding to a site in the ion channel of the N-methyl-D-aspartate (NMDA) receptor was determined in membranes from rat cerebral cortex. Enflurane disrupted glutamate stimulation of [3H]MK-801 (1 nM) binding with an IC50 of 0.4 mM. This inhibition was associated with a decrease in receptor affinity with no change in the number of [3H]MK-801 binding sites. Basal [3H]MK-801 binding measured in the absence of glutamate was not affected by enflurane. In contrast, [3H]CGS-19775 binding to the glutamate recognition site on the NMDA receptor was only weakly inhibited by enflurane (e.g., less than 20% inhibition of 5 nM [3H]CGS binding by 1.2 mM enflurane). Glycine, a positive allosteric NMDA receptor modulator, markedly attenuated the inhibition of glutamate-stimulated [3H]MK-801 binding by enflurane, with an EC50 of approximately 0.8 microM. Thus, enflurane selectively inhibits glutamate activation of the NMDA receptors, and an allosteric modulator attenuates this action. These effects could reflect anesthetic action at the glycine binding site or at another, undefined site which influences activation of the ion channel. These findings raise the possibility that inhibition of transmission at NMDA receptors contributes to the development of the anesthetic state.

Animals↗
PubMed1991

Influence of halothane on the interactions of serotonin1A and adenosine A1 receptors with G proteins in rat brain membranes.

The influence of halothane on the interactions of 5-HT1A and adenosine A1 receptors with G proteins was determined by monitoring the guanine nucleotide sensitivity of agonist binding to these receptors. Halothane inhibited the binding of radiolabeled agonists to 5-HT1A and adenosine A1 receptors by up to 30%, but only at concentrations considerably greater than those necessary for the maintenance of the anesthetic state. The sensitivity of high-affinity agonist binding to a guanine nucleotide (guanylyl-5'-imidodiphosphate) was not affected by halothane, indicating no disruption of receptor-G protein coupling. Thus, it appears that the ability of halothane to disrupt receptor-mediated signal transduction by interference with receptor-G protein interactions is receptor specific.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1991

A two-cycle immunoprecipitation procedure for reducing nonspecific protein contamination.

A two-cycle immunoprecipitation procedure is described that markedly reduces nonspecific protein contamination occurring during the precipitation of hepatic lipase from rat H4 hepatoma cells. In this method, the precipitation of immune complexes during both cycles is achieved by utilizing a sodium dodecyl sulfate (SDS)-washed preparation of lyophilized Staphylococcus aureus cells (Staph A); this washed preparation effectively removes Staph A contaminants without compromising the ability to bind immune complexes. Following initial immunoprecipitation of the antigen, the Staph A/IgG/antigen complex containing coprecipitated nonspecific proteins was dissociated with SDS. Triton X-100 was added to the dissociated immunoprecipitate at a concentration (by weight) of at least 5 parts Triton X-100 to 1 part SDS. A second cycle of immunoprecipitation was then initiated by addition of fresh antibody, followed by Staph A precipitation of immune complexes and analysis by SDS-polyacrylamide gel electrophoresis. The two-cycle procedure is shown to be reproducible and suitable for the quantitative determination of relative amounts of hepatic lipase. The procedure described here is generally applicable to the immunoprecipitation of other antigens.

Antigen-Antibody Complex↗
PubMed1991

Fentanyl and sufentanil inhibit agonist binding to 5-HT1A receptors in membranes from the rat brain.

The influence of several opioid narcotics and related drugs, on the binding of [3H]8-hydroxy-N,N-dipropyl-2-aminotetralin. ([3H]8-OH-DPAT), a serotonergic agonist, to 5-HT1A receptors was determined in membranes from the brain of the rat. Sufentanil and fentanyl inhibited binding of [3H]8-OH-DPAT to hippocampal membranes, with IC50 values of 5.5 and 3.4 microM, respectively. In contrast, IC50 values for meperidine, alfentanil and naloxone exceeded 100 microM. The inhibition of binding by sufentanil appeared to be competitive insofar as 10 microM sufentanil increased the apparent KD from 1.0 +/- 0.1 to 3.9 +/- 0.3 nM, without affecting the number of binding sites and the inhibition was easily reversed. The binding of [3H]8-OH-DPAT to hippocampal membranes was inhibited by 5'-guanylylimidodiphosphate, a stable analogue of GTP, in a concentration-dependent manner. None of the opioid drugs examined altered the sensitivity of binding of [3H]8-OH-DPAT to guanine nucleotides. These results suggest that certain opioid narcotics, disrupt serotonergic neurotransmission as a result of direct interactions with 5-HT1A receptors. No effects of opioid narcotics on 5-HT1A receptor-G protein coupling were noted.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1991

Effects of sodium pentothal and sufentanil on serotonin induced constriction of canine coronary artery rings without endothelium.

1. The individual and combined effects of sufentanil and sodium pentothal on canine coronary artery vasomotor responses to 5-HT were studied in an isolated vascular ring preparation. 2. Clinical concentrations of sufentanil have little effect on basal coronary tension or constriction induced by either 5-HT or sodium pentothal individually, until very high doses greater than 0.26 microM are reached. 3. Sodium pentothal causes coronary constriction at clinical concentrations and this effect is additive and possibly potentiated when combined with 5-HT. 4. Sufentanil inhibits coronary constriction induced by the combination of sodium pentothal and 5-HT.

Anesthetics↗
PubMed1991

Data analysis and sample size issues in evaluations of community-based health promotion and disease prevention programs: a mixed-model analysis of variance approach.

The growing interest in community-based approaches to health promotion and disease prevention (HP/DP) has been accompanied by a growing need to evaluate the effectiveness of such programs. Special issues that arise in these evaluation studies include (1) entire communities are assigned to intervention and control groups, (2) only a small number of communities can usually be studied, (3) the time course of changes in behavior and other outcomes is often of interest, and (4) surveys to measure such changes over time can be conducted with either repeated cross-sectional samples or with longitudinal samples. This paper shows how these issues can be addressed under a mixed-model analysis of variance approach. This approach serves to unify several ideas in the literature on evaluation of community studies, including use of time-series regression and the question of whether the individual or the community should be the unit of analysis. We also describe how the method can be used to estimate sample size requirements, statistical power, or minimum detectable program effect.

Analysis of Variance↗