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Biomedical subjects

T O'Brien

Publications and source records attributed to T O'Brien.

At least 217 records · Page 12Linked to original sources
PubMed1982

Gas-liquid chromatographic-thermal energy analyzer determination of N-nitrosodimethylamine in beer: collaborative study.

The GLC/TEA method for N-nitrosodimethylamine (NDMA) in beer was studied collaboratively by 13 laboratories from 7 countries. Collaborators were asked to analyze a total of 10 randomly labeled samples of beer consisting of the following duplicates: a naturally contaminated commercial beer; a beer extremely low (ca 0.1 ppb) in NDMA; and the low NDMA beer spiked with 0.5, 1.9, and 5.0 ppb NDMA. The pooled repeatability and reproducibility coefficients of variation (CV) for all samples were 17% and 27%, respectively. However, when data from 2 laboratories (outliers) were omitted, the corresponding CV values improved considerably (11% and 15%, respectively). Variance analysis showed the presence of a significant laboratory-sample interaction when all data were used for analysis, but this interaction disappeared when data from the 2 outlying laboratories were excluded. The pooled percent recovery of the overall method (omitting outliers) was 101.4 +/- 3.5. All the laboratories detected NDMA in the low NDMA beer. The method was adopted official first action.

Beer↗
PubMed1981

Prognosis of convulsions between 1 and 6 months of age.

The prognosis of 28 infants presenting consecutively to a general paediatric unit with convulsions between 1 and 6 months of age was far better than had been reported previously. Between 1 and 4 years after presentation the condition of 19 patients was normal, 3 were mildly handicapped, 4 severely handicapped, and 2 had died. Normal physical examination and electroencephalogram at time of presentation, and easy control of convulsions were associated with a satisfactory outcome.

Anticonvulsants↗
PubMed1981

Elevation of voice volume in young developmentally delayed children via an operant shaping procedure.

Unusually low voice volume was identified by teachers as a significant impediment to the academic and social progress of two preschool students. A simple operant shaping procedure was conducted by teachers to increase voice volume using a voice-activated apparatus with attractive visual display. Setting generalization of volume increases to the classroom was achieved and maintained at one- and four-month follow-ups.

Behavior Therapy↗
PubMed1980

Effects of hyperthermia on normal and tumor microenvironment.

The effects of hyperthermia on pH, local blood flow (LBF) and tissue oxygen tension (TpO2) in several normal and tumor tissues were studied. It was found that TpO2, local blood flow and pH are inhomogeneous in tumor tissue. TpO2 is very low in certain areas which also seem deprived of blood flow and are at very low pH. Hyperthermia has a dual effect: at temperatures below 41 degrees C, it increases blood flow and TpO2 while above 41 degrees C, it causes a collapse in blood flow, lower TpO2 and a shift of the tissue pH towards acidosis from the already low pH values found in tumors.

Adenocarcinoma↗
PubMed1980

Feline chronic progressive polyarthritis.

Twenty cats with a chronic progressive polyarthritis were studied. The disorder occurred exclusively in male cats, and all but six of the cats were between 1.5 and 5.0 years of age. There were two forms of the disease as determined by radiographic changes: joint instability and deformity, and clinical course. The most prevalent form of the disease was characterized by osteopenia and periosteal new bone formation surrounding affected joints. Marginal periarticular erosions and collapse of the joint spaces with fibrous ankylosis occurred with time, but joint instability and deformities were not seen. The second form of the disease was characterized by severe subchondral marginal erosions, joint instability, and deformities. The periosteal proliferative form resembled Reiter's arthritis of man, and the deforming type resembled human rheumatoid arthritis. The disease began as tenosynovitis and synovitis, with subsequent changes in the articular cartilage and periosteal bone. Histopathologic changes in these cats were similar to those occurring in both chronic Reiter's and rheumatoid arthritis of man. Chronic progressive polyarthritis of cats was not caused by identifiable bacteria or mycoplasma, but was etiologically linked to feline leukemia virus (FeLV) and feline syncytia-forming virus (FeSFV) infections. The FeSFV was isolated from the blood or was detected by a serologic test in all of the cats with the disease, whereas FeLV was isolated or identified by immunofluorescence technique in 60% of the cats. The arthritis could not be reproduced by inoculation of cell-free cynovial tissue from diseased cats or with tissue culture fluid containing FeSFV and FeLV isolates. It was postulated that arthritis was an uncommon manifestation of FeSFV infection that occurred in predisposed male cats. Feline leukemia virus may not have been directly involved in the disease, but may have acted in some way to potentiate the pathogenic effects of FeSFV.

Animals↗
PubMed1977

Prepartum serum hormone concentrations related to dystocia in Holstein heifers.

Twelve Holstein heifers from a herd having a high incidence of dystocia were bled each day at 0730 h from 260 days gestation until parturition. The blood was analyzed for estradiol-17beta, estrone, 17-hydroxyprogesterone, progesterone, and corticosteroids. Six of the animals had dystocia. The concentrations of estradiol-17beta were lower and the concentration of progesterone higher in dystocial animals during the prepartum period from 23 to 12 days. The prepartum patterns of secretion of corticosteroid, estrone, and 17-hydroxyprogesterone did not change significantly in the two groups between days 23 and 12 prepartum. The prepartum difference in serum estradiol-17beta and progesterone concentration between normal and dystocial animals suggests that the timing of hormone changes in preparation for parturition is delayed and not as pronounced in dystocial animals.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Surgical management of insulinoma associated with multiple endocrine neoplasia type I.

Insulinoma in patients with multiple endocrine neoplasia (MEN) is a rare condition that because of its usual multicentricity presents difficulties not encountered in sporadic patients. In contrast to gastrinoma, which is the most common pancreatic neoplasm associated with MEN I, malignancy and duodenal tumors are much less common for patients with insulinomas, and excellent palliative medication is not available. Accordingly, there is a much greater reliance on surgical therapy for this group of patients. Between 1970 and 1991 a total of 19 patients had surgical treatment of MEN I-related insulinoma. Each patient had hyperinsulinemic hypoglycemia. One patient, with extensive metastases, had unresectable disease. Of the remaining 18, there were 16 (89%) multiple pancreatic tumors. Tumors were located in the neck, body, or tail in 17 cases, 10 of whom also had tumors in the head. Pancreatic resections performed were 1 total, 12 subtotal (7 also had enucleation of tumors from the pancreatic head), and 5 limited distal resections and/or enucleation (conservative resection). There was no operative mortality. One patient developed pancreatitis, fistula, and diabetes following subtotal resection and enucleation. Postoperative cure was achieved in 17 of 18 cases. Recurrent disease occurred in 2 of 5 conservative resections compared to 0 of 12 subtotal resections, with median follow-up times of 10.4 and 10.3 years, respectively. During the follow-up period, four patients died, possibly all due to MEN I-related conditions. Hyperinsulinism in MEN I is associated with the occurrence of multiple, usually benign, pancreatic islet cell tumors, and surgery is an effective treatment modality.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Evaluation of the syndesmotic screw in low Weber C ankle fractures.

OBJECTIVE: To determine the functional and radiographic outcome of low Weber C ankle fractures and to evaluate the contribution of the syndesmotic screw in their outcome. DESIGN: Prospective evaluation of a consecutive series. SETTING: Level I trauma center. PATIENTS: Forty-five patients divided into two groups matched for age, sex, and severity of injury. Twenty-six patients were treated with open reduction, internal fixation, and a supplemental syndesmotic screw, and nineteen patients were treated without a syndesmotic screw. Minimum time to follow-up was three years. METHODS: A subjective, objective, and radiographic ankle scoring system was used. Logistical regression analysis was performed to determine whether the presence or absence of a syndesmotic screw was a predictor of a poor outcome. The likelihood ratio test was used to evaluate the significance of each variable in both univariate and multivariate analyses. RESULTS: There was no statistically significant difference between either group, either using subjective outcome criteria (p = 0.86) or in ankle range of motion (p = 0.94). Logistical regression analysis indicated that fracture dislocation could be used as a predictor of a poor outcome for either group. Inadequate reduction and advancing age were also found to be significant predictors of a poorer outcome regardless of the use of a syndesmotic screw (p = 0.003, p = 0.004). CONCLUSIONS: Judicious fixation of Weber C type injuries within five centimeters of the ankle joint, with or without a syndesmotic screw, gives similar results. Obligatory fixation of these fractures with syndesmotic screws appears to have no benefit and creates the need for an additional procedure.

Adolescent↗
PubMedDate not supplied

Femoral head size in congenital dislocation of the hip.

Observations on the size of the femoral head in congenital dislocation of the hip are presented. The long-term effects of open reduction and innominate osteotomy on the size of the femoral head are assessed. Innominate osteotomy does not cause overgrowth of the femoral head, although open reduction results in mild coxa magna. The pathophysiology and significance of coxa magna are discussed.

Adolescent↗
PubMedDate not supplied

Distal forearm fractures in children: the role of hand dominance.

A survey of 426 children with unilateral distal forearm fractures was performed to examine the role of hand dominance. Results showed a significant preponderance of fractures occurring in the non-dominant arm (p < .01). This finding has implications for possible preventive strategies in these common injuries.

Child↗
PubMedDate not supplied

L-arginine availability is not limiting for nitric oxide generation from recombinant endothelial nitric oxide synthase.

L-arginine (L-Arg) may be limiting for inducible nitric oxide synthase (NOS) activity and under certain circumstances, such as increased concentrations of a NOS inhibitor, may also be limiting for endothelial NOS activity. It is unknown if L-Arg is limiting for recombinant eNOS activity in the vascular wall after adenoviral mediated gene transfer. Our aim was to examine, if L-Arg is limiting for recombinant eNOS activity in the normal or atherosclerotic vessel wall. Rings of rabbit aorta from chow or cholesterol fed animals were transduced with adenovirus vector encoding eNOS (AdeNOS) or beta-galactosidase (AdbetaGal). After 24 h, transgene expression was confirmed and vasomotor studies were performed in the absence or presence of L-Arg. During maximal contractions to phenylephrine (10(-5) M), L-Arg (3 mM) was added to the organ chamber for 30 min. Subsequently, relaxations to acetylcholine during half-maximal contractions were obtained. In the chow- and cholesterol-fed animals, relaxations were significantly enhanced in the NOS and NOS + L-Arg groups compared to the betaGal and betaGal + L-Arg groups. There was no difference between NOS and NOS + L-Arg or betaGal and betaGal + L-Arg rings from chow- or cholesterol-fed animals. While gene transfer of eNOS enhances endothelium-dependent vasorelaxation in the normal and atherosclerotic vessel wall, L-arginine is not limiting for recombinant eNOS activity.

Animals↗
PubMedDate not supplied

Expression and function of recombinant endothelial nitric oxide synthase in human endothelial cells.

Endothelial dysfunction is frequently involved in the pathogenesis of vascular disease. While nitric oxide (NO) inhibits smooth muscle cell proliferation, its effect on endothelial cell proliferation is unclear. The aim of this study was to determine if adenoviral-mediated gene transfer of endothelial NO synthase (eNOS) to human umbilical vein endothelial cells (HUVECs) would result in increased generation of NO and affect endothelial cell proliferation. HUVECs were transduced with adenoviral vectors encoding eNOS (AdeNOS) or beta-galactosidase (Ad beta gal) or exposed to diluent (control). AdeNOS-transduced cells showed increased eNOS expression as detected by Western blot analysis, and increased concentrations of cGMP (control 0.7 +/- 0.1; Ad beta gal 0.9 +/- 0.2; AdeNOS 3.1 +/- 0.5 pmol/mg protein; p < 0.001) and nitrite (control 11.8 +/- 1.2; Ad beta gal 13.3 +/- 1.7; AdeNOS 21.1 +/- 2.2 nmol/mg protein/hour; p < 0.01). DNA synthesis as assessed by [(3)H]thymidine incorporation and cell counts were significantly reduced (by approximately 30%) in AdeNOS-transduced HUVECs. Expression of mitogen-activated protein kinase was also decreased in AdeNOS-transduced cells. This study shows that adenoviral-mediated gene transfer of eNOS to HUVECs inhibits endothelial cell proliferation.

Adenoviruses, Human↗