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Biomedical subjects

R A Martin

Publications and source records attributed to R A Martin.

At least 19 recordsLinked to original sources
PubMed1992

Pentalogy of Cantrell and ectopia cordis, a familial developmental field complex.

The association of sternal fusion defects with various cardiac, diaphragmatic, and anterior body wall defects represents a developmental field complex that includes the Pentalogy of Cantrell and ectopia cordis. No familial cases have been reported previously. We present 3 consecutively born brothers with extensive diaphragmatic defects, 2 who had the Pentalogy of Cantrell. One of the 2 also had ectopia cordis.

Adult↗
PubMed1992

Congenital absence of the vas deferens: recurrence in a family.

We report on 2 brothers with congenital absence of the vas deferens discovered in childhood during inguinal hernia repairs. The vas is absent unilaterally in one sib and bilaterally in the other. The unusual presentation of inguinal hernias in these children is discussed as well as mechanisms of inheritance and associated risk of renal anomalies.

Child, Preschool↗
PubMed1992

Differential analysis of animal bone marrow by flow cytometry.

A simple procedure was developed for rapid analysis of animal bone marrow by flow cytometry using the lipophilic cationic dye 3,3'-dihexyloxacarbocyanine iodide [DiOC6(3)]. The batch process allows differentiation of bone marrow cells into lymphoid, erythroid, and myeloid populations and enables classification of erythroid and myeloid cells into proliferating and maturing subpopulations. From these data, myeloid:erythroid (M:E) ratios and maturation indices for erythroid and myeloid cells (EMI and MMI, respectively) can be derived. This procedure provides the opportunity to analyze bone marrow quantitatively and offers distinct advantages to current manual methods in terms of simplicity, throughput, and reproducibility. The method has been tested successfully using marrow from Wistar rats, B6C3F1 mice, beagle dogs, and cynomolgus monkeys. This technique facilitates the evaluation of bone marrow samples taken from preclinical safety studies or from animal colonies of large size.

Animals↗
PubMed1992

Effect of ACE inhibition on the fetal kidney: decreased renal blood flow.

The kidneys of nine fetuses whose mothers were chronically hypertensive were examined microscopically. Three of these mothers used antihypertensive agents throughout pregnancy including one who used an angiotensin-converting enzyme (ACE) inhibitor. The tubular defects found in these kidneys were compared to the kidneys of 20 normal controls, 13 fetuses with various multiple malformation syndromes and six cases of the twin to twin transfusion syndrome. Evidence from these cases as well as the literature suggest that the primary mechanism by which ACE inhibitors affect development of the fetal kidney is through decreased renal blood flow.

Abnormalities, Drug-Induced↗
PubMed1992

Chronic toxicity and carcinogenicity studies with the beta-adrenoceptor antagonist levobunolol.

The chronic toxicity and carcinogenicity of levobunolol, a nonselective beta-adrenoceptor antagonist, was evaluated in Swiss mice and Wistar rats. The drug was administered in the diet to mice at 0, 12, 50, and 200 mg/kg/day for 80 weeks and to rats at 0, 0.5, 2, 5, 30, and 180 mg/kg/day for 2 years. In mice, uterine leiomyomas were present in 4 of 50 females at 200 mg/kg but not in any other group. The incidences of other tumor types, as well as pathologic findings, were comparable among groups. In rats, significant body weight gain suppression occurred at 5, 30, and 180 mg/kg. Brown discoloration of perianal fur and steel-gray discoloration of hairless skin were evident in high-dose rats. A generalized steel-gray discoloration of internal organs and tissues occurred in the 30 and 180 mg/kg groups. No other differences between treated and control groups were evident. The clinical relevance of the increased incidence of uterine leiomyoma in mice is questionable because it occurred only in one species at more than 200 times the projected therapeutic dose.

Adrenergic beta-Antagonists↗
PubMed1992

Functional, radiographic, and histologic assessment of healing of autogenous osteochondral grafts and full-thickness cartilage defects in the talus of dogs.

A circular (5.5 mm diameter) full-thickness cartilage defect was created on the medial ridge of the talus in 12 skeletally mature dogs. In 6 dogs, the articular surface of the lesion was repaired, using an osteochondral graft obtained from the ipsilateral manus. The graft (digit I, first phalanx, distal articular surface and diaphysis) was contoured to obtain a press fit in the drilled talar recipient site. In 6 dogs, the lesion was not treated and healed by fibrous tissue replacement. Functional assessment (lameness, hock range of motion, joint stability, joint crepitus, and mid-femoral muscle circumference) was completed before surgery and at postoperative weeks 2 through 20. Radiographic assessment (periarticular soft tissue width, joint space width, osteophyte formation, and graft incorporation) was completed before surgery and at postoperative weeks 0, 6, 12, and 20. To facilitate histologic assessment, tissues were stained with toluidine blue and H&E. Histologic assessment of the articular surface on the surgically treated talus, ipsilateral tibia, and contralateral talus was completed, using a modification of the Mankin grading system. Subchondral bone was examined to assess graft viability and incorporation. Analysis of the ordinal data was completed, using a Mann-Whitney rank sum test. All dogs were fully weight bearing by postoperative week 7. Dogs without grafts had significantly (P = 0.036) better clinical function at postoperative week 6. Significant difference in functional assessment was not evident at postoperative week 20. Immediate postoperative radiographic assessment revealed significant (P = 0.005) difference between nongrafted and grafted groups. Significant difference was not observed at postoperative week 6, 12, or 20. All grafts appeared radiographically incorporated by postoperative week 12. All grafts restored joint surface congruity, whereas 3 of 6 nongrafted lesions had poor articular congruity. Of 6 grafts, 4 partially retained normal hyaline cartilage, resulting in significantly (P = 0.014) lower Mankin grades. Significant histologic differences between groups were not apparent when the apposing tibia and control talus were examined. Talar reconstruction by use of a phalangeal osteochondral graft is a viable surgical procedure. These data indicate that normal articular and subchondral architecture are more closely approximated by osteochondral reconstruction than by fibrous tissue repair.

Animals↗
PubMed1992

Investigation of glomerular lesions in dogs with acute experimentally induced Ehrlichia canis infection.

Six male Beagles were inoculated with Ehrlichia canis. Transient proteinuria was confirmed during the acute phase of infection by serial determination of urinary protein-to-creatinine ratio. Peak urine protein loss, consisting principally of albumin, was observed 2.5 to 3.5 weeks after inoculation. Renal biopsy specimens were obtained before inoculation, during peak proteinuria, and 10 weeks after inoculation when proteinuria had resolved. Renal tissue was evaluated by use of light, immunofluorescent, and electron microscopy to correlate specific glomerular lesions with development of proteinuria. Histologic examination revealed perivenular and interstitial infiltrates of lymphocytes and plasma cells localized principally to the renal cortex. Glomerular lesions were minimal to absent. Immunofluorescent staining revealed moderate to marked deposition of anti-canine IgG and IgM in the glomerular tufts and mesangium. Depositions of anti-canine complement factor C3 were not observed. Immunofluorescent staining persisted 10 weeks after inoculation, despite resolution of proteinuria, and probably represented passive trapping of immunoglobulins. Ultrastructural examination revealed fusion of podocyte processes that coincided with development of proteinuria. Electron-dense deposits or changes in the basement membrane were not observed. Morphometric measurements of average podocyte process length and percentage of coverage of basement membrane by podocyte processes were used to quantify the degree of process fusion. Both measurements increased significantly (P < 0.05) during peak proteinuria, and returned to preinoculation values when proteinuria had resolved 10 weeks after E canis inoculation. These findings indicated possible minimal-change glomerulopathy, rather than immune-complex glomerulonephritis, during acute E canis infection and could explain transient proteinuria without histologic evidence of glomerular disease.

Animals↗
PubMed1992

Rectovaginal fistula with atresia ani in three kittens.

Rectovaginal fistula with atresia ani was diagnosed in 3 kittens. Physical abnormalities included abdominal distension, bulging of the perineum, and lack of an anal opening. Vaginography was helpful in determining the type of malformation present in 2 cases. In each kitten attempts were made to surgically correct the anatomic malformations. Various post-operative complications such as fecal incontinence, would dehiscence, constipation, and excessive scar tissue formation occurred and are discussed.

Anal Canal↗
PubMed1991

Delineation of the Costello syndrome.

We present a 15-year-old girl with mental retardation, short stature, coarse face, unusually thick, loose skin of the hands and feet, deep plantar and palmar creases, and nasal papillomata. Her history and physical findings are compared to those of 2 children initially reported by Costello and to 1 child recently reported by Der Kaloustian et al.

Adolescent↗
PubMed1991

In vitro regulation of B cell differentiation by interleukin-6 and soluble CD23 in systemic lupus erythematosus B cell subpopulations and antigen-induced normal B cells.

Polyreactive systemic lupus erythematosus (SLE) B cells were compared with antigen-induced SLE and normal B cells for their interleukin-6 (IL-6) and soluble CD23 requirements. Unlike normal B cells, secretion of antibody by SLE B cells in serum-free medium was not enhanced by exogenous IL-6. Anti-IL-6 antibodies inhibited immunoglobulin production in cultures of normal and SLE B cells, which suggests that IL-6 is required for B cell differentiation. SLE culture supernatants had elevated levels of IL-6, which explains the poor response of the SLE cells to exogenous IL-6. Soluble CD23 enhanced the responses of cells from normal subjects and SLE patients.

Adult↗
PubMed1991

Effects of CI-949, a novel antiallergy compound, on host resistance in mice.

The effect of CI-949, a novel inhibitor of allergic mediator release, on immune function was assessed with holistic mouse models of immunocompetence. Resistance to the bacterial pathogens Listeria monocytogenes and Streptococcus pneumoniae and the B16F10 melanoma cell line was used to evaluate the potential of CI-949 to affect immune function. CI-949 treatment of female B6C3F1 mice increased pulmonary tumor burden at 100 mg/kg/day in the B16F10 melanoma model, with a no effect level of at least 50 mg/kg/day. A correlation was seen between decreased clearance of the B16F10 cells and increased tumor burden. However, CI-949 produced this effect only at the maximum tolerated dose. No effect of the drug was seen in the S. pneumoniae model. Host resistance to L. monocytogenes was increased after CI-949 administration, with the no adverse effect level in this model being at least equivalent to the top dose of 100 mg/kg/day. Therefore, the immune system does not appear to be adversely affected or to be a specific target for CI-949 even at an overtly toxic dose.

Animals↗
PubMed1991

Cytokine production and lymphocyte transformation during stress.

The production of interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN gamma) and blast transformation in peripheral blood mononuclear cells were assessed in medical students writing an academic examination. Blood samples were obtained on three occasions: (1) 1 month prior to the examination during a period of relatively low academic demand; (2) immediately after the examination; and (3) 10 days later. Results indicated that immune responses were significantly different immediately after the examination compared with the baseline and postexam measures. Lymphocyte responsiveness to both concanavalin A and pokeweed mitogen was decreased, as was the production of IFN gamma, supporting earlier reports of immunosuppression after relatively commonplace stressors. In contrast to predictions, IL-1 beta production was significantly elevated after the examination. Cortisol levels were also measured, but did not change across the three sample points. Our finding of an increase in IL-1 beta production suggests that stress may have different effects on different cell populations by enhancing the responses of monocytes and depressing those of lymphocytes.

Adult↗
PubMed1991

Degradation of growth hormone releasing factor analogs in neutral aqueous solution is related to deamidation of asparagine residues. Replacement of asparagine residues by serine stabilizes.

The incubation of a solution of the human growth hormone releasing factor analog, [Leu27] hGRF(1-32)NH2 at pH 7.4 and 37 degrees, resulted in extensive degradation of the sample. The major degradation products were identified as the peptides [beta-Asp8, Leu27] hGRF(1-32)NH2 and [alpha-Asp8, Leu27] hGRF(1-32)NH2, produced by deamidation of the Asn8 residue. When tested as growth hormone (GH) secretagogues in cultured bovine anterior pituitary cells, [beta-Asp8, Leu27] hGRF(1-32)NH2 was estimated to be 400-500 times less potent than the parent Asn8 peptide, while [alpha-Asp8, Leu27] hGRF(1-32)NH2 was calculated to be 25 times less potent than the parent Asn8 peptide. Three additional analogs of [Leu27] hGRF(1-32)NH2 containing either Ser or Asn at positions 8 and 28 were prepared and evaluated for their GH releasing activity and stability in aqueous phosphate buffer (pH 7.4, 37 degrees). Based on disappearance kinetics, [Leu27] hGRF(1-32)NH2 had a half-life of 202 h while the other analogs had the following half-lives: [Leu27, Asn28] hGRF(1-32)NH2 (150 h); [Ser8, Leu27, Asn28] hGRF(1-32)NH2 (746 h); and [Ser8, Leu27] hGRF(1-32)NH2 (1550 h). After 14 days, incubated samples of the Asn8 analogs lost GH releasing potency, while the Ser8 analogs retained full potency. The potential for loss of biological activity brought about by deamidation of other engineered peptides and proteins should be considered in their design.

Amides↗
PubMed1991

Species differences in response to photohemolytic agents.

Species differences in red blood cell susceptibility to the photohemolytic agents chlorpromazine, menadione and tetracycline were examined in mouse, rat, dog, and human blood. Menadione and tetracycline (25 microM) hemolyzed mouse but not dog, rat, or human red blood cells (RBC) when irradiated with UV light but not in the dark. Chlorpromazine (25 microM) produced a photohemolytic response in all four species with mouse and rat RBC lysing fastest followed by human then dog cells. Investigations into the nature of these species differences suggested that the size of mouse RBC may contribute to its high sensitivity to photohemolytic agents. An investigation of the effect of UV light on key antioxidant enzymes revealed species differences in enzyme inactivation. These data suggest that mouse RBC may be particularly vulnerable to phototoxic agents, especially those compounds which produce active oxygen species and, therefore, may prove more useful than human RBC as a model for predicting phototoxic potential of some chemical entities.

Animals↗
PubMed1991

Cleft palate repair.

Cleft palates are congenital or acquired and effect the primary palate (lip) or the secondary (hard and soft) palate. Surgical repair of congenital cleft palate is indicated at an early age. Preservation of maximal tissue and tissue blood supply and a tension-free closure of the defect are requisite for successful repair. Multiple surgical procedures are often performed prior to resolution of this problem. Aspiration pneumonia is often present concurrently and should be treated with appropriate antibiotic therapy.

Anesthesia, Inhalation↗
PubMed1991

Effect of left hepatic vein ligation on hepatic circulation, function, and microanatomy in dogs.

Eighteen healthy dogs were allotted to 3 groups (n = 6 dogs each). All dogs were evaluated at the beginning of the study by complete physical examination; total and differential WBC counts; serum biochemical analysis (alanine transaminase and alkaline phosphatase activities and bilirubin and albumin concentrations); sulfobromophthalein excretion, ammonia tolerance, and glucagon response testing; portal and intraparenchymal pressure determinations; operative mesenteric portography; and histologic assessment of hepatic biopsy specimens. The left hepatic vein was ligated completely in dogs of groups 1 and 2. Group-3 (control) dogs had a ligature placed loosely around the left hepatic vein. Dogs of groups 1 and 3 were reevaluated 24 hours after surgery by use of the aforementioned hematologic and biochemical tests. Group-1 dogs were reevaluated by use of portal and intraparenchymal pressure determinations, jejunal vein portography, and complete necropsy at 48 hours after surgery. At 4 weeks after surgery, dogs of groups 2 and 3 were reevaluated by use of all aforementioned tests. Results indicated transient hepatic congestion, which resolved by the fourth postoperative week. Longstanding effect on hepatic structure, circulation, or function was not found. We concluded that left hepatic vein ligation in clinically normal dogs does not cause severe or permanent liver damage.

Alanine Transaminase↗