Search PubMed⌕ Search

Biomedical subjects

B Smith

Publications and source records attributed to B Smith.

At least 271 records · Page 15Linked to original sources
PubMed1992

CAPD disconnect systems: UK peritonitis experience.

We reviewed peritonitis (P) experience of four UK units using single use Y (Freeline T.M., Baxter UK)(F) and Twinbag (Solo T.M., Baxter UK) (S) disconnect systems, which incorporate the 'Flush Before Fill' principle. We aim to show clinical achievements, in varying circumstances, in the light of previously published in vitro study results. Each unit recorded P data, i.e., rates, causative organisms, and recurrences (R) over a 12 month period (Sept 89-Aug 90). This data was then analysed by system, by unit and in total. Each unit had similar definitions for P and R, but had varying system selection criteria. Unit 1 had a fairly open criteria for F use, then became more selective at the same time as introducing S. In unit 2, F, and then S, were first choice systems for all (inc. blind diabetics). Unit 3 trains every pt. on non-disconnect System 2, then pt. choice determines if they are retained onto a disconnect system. Unit 4 had a more highly selected population. Results, expressed as episodes/patient month, were as follows: [table: see text] We conclude that it is possible to achieve a low incidence of P, especially that caused by S. epidermidis, particularly with S. It would seem the extent is related to pt. to system selection criteria. The effects of R and ES/TI need to be addressed.

Humans↗
PubMed1992

Oral ketamine premedication to alleviate the distress of invasive procedures in pediatric oncology patients.

This study prospectively evaluated the efficacy of oral ketamine in alleviating procedure-related distress in pediatric oncology patients. Ketamine (10 mg/kg) was administered orally to 35 children and adolescents, ranging in age from 14 months to 17 years (mean = 6.5 years). Procedure-related distress was evaluated by using parent/clinician ratings and the Observational Scale of Behavioral Distress (OSBD-R). Eighty-seven percent of children were sedated within 45 minutes. Clinician and parent ratings were similar, with 77% rating procedural distress as low (0 to 3). The OSBD-R scores were low throughout all phases of the study. Although this study was neither randomized nor placebo-controlled, statistical comparison of the OSBD-R scores of the patients who received oral ketamine with those of historical controls (from a study previously performed at the same institution but using intravenous midazolam) showed significantly less distress (P < .001) during the procedure in children who received oral ketamine. Additionally, OSBD-R scores of the patients who received oral ketamine were significantly lower (P < .001) during all phases than those of the saline placebo group in the other study. No cardiorespiratory side effects related to ketamine were noted. The majority of patients showed recovery from sedation within 2 hours following the procedure. In conclusion, oral ketamine effectively alleviated procedure-related distress in pediatric oncology patients.

Administration, Oral↗
PubMed1991

Detection of melanoma cells in peripheral blood by means of reverse transcriptase and polymerase chain reaction.

Only small numbers of cells from solid tumours are needed for haematogenous metastasis. Detection is difficult because existing techniques are not sensitive enough. We have used reverse transcriptase to make complementary DNA from peripheral blood messenger RNA, and the polymerase chain reaction (PCR) to amplify cDNA specific for a gene actively transcribed only in the tumour tissue type. We prepared cDNA from peripheral blood of seven patients with malignant melanoma, four patients with other metastatic cancers, and four healthy subjects, as well as from several melanoma-derived cell lines. PCR was used to amplify the gene for tyrosinase, a tissue-specific gene in melanocytes. Since normal melanocytes are not thought to circulate in peripheral blood, detection of tyrosinase transcription in peripheral blood should indicate the presence of circulating cancer cells. The method was highly sensitive and could detect a single melanoma cell from a cell line in 2 ml normal blood. Blood samples from four of the seven patients with malignant melanoma gave positive results, whereas all eight control subjects gave negative results. This method does not depend on the characterisation of cancer-specific genetic abnormalities and can be applied to any cancer for which tissue-specific genes can be identified, including epithelial cancers. It could prove useful in the diagnosis of primary or metastatic cancers, in assessing prognosis, and in detecting residual disease after treatment.

Amino Acid Sequence↗
PubMed1991

Biochemical characterization of histamine H1 receptors in bovine adrenal medulla.

Bovine adrenal medullary membranes display high affinity and saturable binding to [3H]mepyramine, a selective H1 antagonist, with Kd of 1.5 +/- 0.1 nM and Bmax of 694 +/- 12 fmol/mg protein. [3H]Azidobenzpyramine, an azidobenzamide derivative of mepyramine, was synthesized and used to photolabel the high affinity mepyramine binding sites. Following photolysis, a protein component with an approximate molecular weight of 53-58 kDa was shown to be covalently labeled, as judged by gel filtration and SDS/PAGE; labeling being greatly reduced in the presence of excess unlabeled mepyramine. These results indicate that bovine adrenal medulla expresses a large number of H1 receptors, which are pharmacologically and biochemically indistinguishable from the H1 receptor of many other tissues of various species.

Adrenal Medulla↗
PubMed1991

Selective modification by transglutaminase of a glutamine side chain in the hinge region of the histidine-388----glutamine mutant of yeast phosphoglycerate kinase.

The transglutaminase-catalysed incorporation of putrescine and monodansylcadaverine into yeast phosphoglycerate kinase has been studied. There is little incorporation of the amines into wild-type enzyme, but nearly stoichiometric incorporation into the histidine-388----glutamine mutant enzyme. C.d. studies show that the overall structure of the mutant enzyme is very similar to that of the wild-type enzyme. Incorporation of the amines into the mutant enzyme causes no significant change in its activity. Glutamine-388 was shown, by isolation and sequencing of the modified peptide, to be the site of incorporation of monodansylcadaverine into the mutant enzyme. The specificity of the transglutaminase reaction is discussed in the light of available data.

Amino Acid Sequence↗
PubMed1991

Optimal control system for the intra-aortic balloon pump.

An optimal control system for the intra-aortic balloon pump (IABP) is presented. Control of the IABP is based on a performance index formulated to reflect a tradeoff between maximising cardiac oxygen supply and minimising cardiac oxygen consumption. In the performance index, mean diastolic pressure (MDP) was used to represent oxygen availability and peak systolic pressure (PSP) was used to represent oxygen consumption. An algorithm, implemented using an 8-bit microcomputer, changes the deflation time of the IABP to maximise this performance index by using an optimisation technique that employs both a search and an approximation. The search produces three equally spaced points which define a region that includes the maximum of the performance index. From these points, the optimum deflation time is estimated by a quadratic approximation. The algorithm has been successfully tested using performance index curves generated by computer simulations.

Algorithms↗
PubMed1991

A comparison of islet transplantation and subcutaneous insulin injections for the treatment of diabetes mellitus.

Transplantation of the islets of Langerhans has received considerable attention as a means of treating insulin-dependent diabetes mellitus. However, the number of islets needed and the level of plasma glucose control that results from this treatment method still needs to be defined. A pharmacokinetic model of glucose and insulin dynamics which includes the islet insulin response to plasma glucose is used to compare the effectiveness of subcutaneous insulin injections and transplanted islets of Langerhans for the treatment of a hypothetical patient with insulin dependent diabetes mellitus. For a patient receiving 60 U of insulin per day the results show that 500,000 human islets would be needed to obtain glucose control comparable to that obtained with insulin injections and at least 1.5 million human islets are needed to obtain normoglycemia.

Animals↗
PubMed1991

Results of TV imaging of Phobos (Experiment VSK-Fregat).

From February to March 1989 the Phobos 2 spacecraft took 37 TV images of Phobos at a distance of 190-1100 km. These images complement Mariner-9 and Viking data by providing higher-resolution coverage of a large region West of the crater Stickney (40-160 degrees W) and by providing disk-resolved measurements of surface brightness at a greater range of wavelengths and additional phase angles. These images have supported updated mapping and characterization of large craters and grooves, and have provided additional observations of craters' and grooves' bright rims. Variations in surface visible/near-infrared color ratio of almost a factor of 2 have been recognized; these variations appear to be associated with the ejecta of specific large impact craters. Updated determinations of satellite mass and volume allow calculation of a more accurate value of bulk density, 1.90 +/- 0.1 g cm-3. This is significantly lower than the density of meteoritic analogs to Phobos' surface, suggesting a porous interior perhaps containing interstitial ice.

Astronomy↗
PubMed1991

Dialysis-induced alterations in left ventricular filling: mechanisms and clinical significance.

Quantitative two-dimensional (2-D) and Doppler echocardiography were used to determine whether hemodialysis results in alterations in left ventricular (LV) diastolic filling that might contribute to dialysis-induced hypotension, as well as to assess whether any hemodynamic variables or indices of diastolic filling might be used to identify which patients were at the greatest risk of becoming hemodynamically unstable during dialysis. Sixteen male patients undergoing routine maintenance hemodialysis for end-stage renal disease were prospectively studied before and after hemodialysis. Following hemodialysis there was a significant prolongation (P less than 0.05) in LV isovolumetric relaxation time (IVRT), as well as a significant reduction in the rate and extent of early rapid ventricular filling (P less than 0.005); in contrast, late atrial-assisted filling did not change significantly. A multiple stepwise linear regression analysis of predialysis hemodynamic parameters and noninvasive indices of LV filling showed that there was a significant independent inverse relationship between the frequency of dialysis-related hypotensive episodes and the duration of early LV filling (r = -0.81; P less than 0.001). These results suggest that hemodialysis results in discrete alterations in early LV filling, with no significant compensatory increase in late atrial-assisted ventricular filling. Further, patients with the shortest early LV filling times appeared to have the greatest predilection for becoming hemodynamically unstable during dialysis.

Aged↗
PubMed1991

Treatment of Aptitude X Treatment interactions.

The main effects in psychotherapy research have been smaller than expected. Rather than concluding that psychotherapy has weak effects, clinical researchers have argued that average effect sizes are reduced because of mismatches between clients and treatment. Hence, Aptitude X Treatment interaction (ATI) research has been viewed as a promising new frontier in psychotherapy research. If ATI research is to become a productive and progressive program, then researchers will need to focus their attention on interesting and meaningful ATIs. This will require greater theoretical precision and a stronger emphasis on construct validity. Specific issues addressed in this article include Type II and Type III errors, manipulation checks from both the patient and practitioner perspective, considerations of the strength of treatment, the need to test rival hypotheses, and the desirability of collaborative research.

Aptitude↗
PubMed1991

Induction of HLA-DR by interferon-gamma requires a trypsin-like protease.

Induction of HLA-DR antigen expression by interferon-gamma (IFN-gamma) is inhibited by trypsin inhibitors and an anti-trypsin monoclonal antibody, but not by chymotrypsin inhibitors, suggesting a requirement for trypsin-like protease (TLP) activity in IFN-gamma-induced HLA-DR expression. Using p-nitroanilide and thioester substrates, TLP activity was demonstrated in cellular extracts of a hybrid epidermal cell line and judged to be essential for HLA-DR expression. TLP activity was inhibited by the trypsin inhibitors soybean trypsin inhibitor, ovomucoid trypsin inhibitor, and tosyl-lysyl-chloromethyl ketone and by an anti-trypsin monoclonal antibody, closely paralleling inhibition of HLA-DR expression by such agents. TLP activity was enhanced by exposure to trypsin-linked agarose, indicating that the protease normally exists in an inactive form, perhaps in an enzyme-inhibitor complex or as an activatable proenzyme. Finding glucocorticoids (GC) to also inhibit IFN-gamma-induced HLA-DR expression and to regulate serine protease, especially urokinase plasminogen activator (uPA), activity raised the possibility of GC regulation of TLP activity. However, TLP activity was found to be constitutively expressed, regulated by neither GC nor IFN-gamma, nor was uPA activity involved in HLA-DR regulation. Trypsin inhibitors and GC also inhibited induction of intracellular 2',5'-oligoadenylate (2-5A) synthetase by IFN-gamma. Thus, TLP activity is required for IFN-gamma induction of HLA-DR and 2-5A synthetase.

2',5'-Oligoadenylate Synthetase↗
PubMed1991

In-line lead connector for use with implanted neuroprosthesis.

The design, implementation, and preliminary testing of an implantable in-line connector for individual lead-wires is presented. The connector provides for replacement of implanted components without disturbing other elements of the implanted system. Its flexibility and size makes it suitable for implantation in neuromuscular applications.

Animals↗
PubMed1991

Expression of SV40 T antigen under control of rabbit uteroglobin promoter in transgenic mice.

The rabbit uteroglobin gene is expressed in the lungs and reproductive tracts of male and female rabbits. To examine whether the promoter region of the uteroglobin gene could be used to target a heterologous gene to the lungs of transgenic mice, a fusion gene consisting of 3.3 kb of the 5'-flanking region of the rabbit uteroglobin gene and the large T antigen gene of the SV40 virus was constructed and microinjected into the pronuclei of one-cell mouse embryos. Eleven founder transgenic mice (5 female and 6 male) were generated. Seven of these mice developed bronchioalveolar neoplasms. Four of the founder males also developed primitive undifferentiated urogenital tract tumors. One founder female and one female offspring of a founder male developed glandular paraovarian tumors. Northern analysis revealed that the predominant site of expression of the transgene was the lung. Immunohistochemical staining showed T antigen predominantly in epithelial cells lining the bronchioles, the submucosal glands of the trachea, and the neoplasms. There appeared to be a high level of mosaicism for the transgene in the founder mice, with poor transmission of the transgene to subsequent generations. This suggests that, under the control of the uteroglobin promoter, the T antigen gene may be lethal to the fetus.

Animals↗
PubMed1991

Fructose-1,6-diphosphate, when given five minutes after injury, does not ameliorate hypoxic ischemic injury to the central nervous system in the newborn pig.

Hypoxic ischemic injury to the brain was induced in 12 0- to 3-day-old piglets. At time 0, the carotid arteries were ligated, and the blood pressure was reduced by one third by hemorrhage. At 15 min, inspired FIO2 was reduced from 50 to 6%. After 10 min of flat EEG, the FIO2 was changes to 100%, the carotid ligations were released, and the withdrawn blood was reinfused. Five minutes after reoxygenation, the piglets were randomly assigned to either receive 350 mg of fructose-1,6-diphosphate over 5 min, followed by 6 mg/kg/min for the ensuing 50 min, or an equivalent volume of normal saline. 3 days after the experiment, the animals received a neurologic examination by a blinded observer, were then sacrificed, and the brains examined by a blinded observer. There were no significant differences in the degree of damage between the two groups.

Animals↗
PubMed1991

MK-801 does not protect against hypoxic-ischemic brain injury in piglets.

BACKGROUND AND PURPOSE: The excitatory amino acid inhibitor MK-801 has been shown in many animals species to protect against hypoxic-ischemic brain injury. We sought to determine whether hypoxic-ischemic injury to the newborn pig's brain could be prevented by the use of MK-801. METHODS: Hypoxic-ischemic injury to the brain was induced in forty 0-3-day-old piglets. They were randomized to receive either 3 mg/kg MK-801 (MK-801 group, n = 20) or vehicle (control group, n = 19) prior to insult. At time 0, the carotid arteries were ligated and the blood pressure was reduced by one third by hemorrhage. At 15 minutes, inspired oxygen was reduced from 50% to 6%. At 30 minutes, inspired oxygen was changed to 100%, carotid ligatures were released, and the withdrawn blood was reinfused. An additional 14 piglets received 3 mg/kg MK-801 but not hypoxic-ischemic injury (drug-only group), and a final group of 11 piglets were subjected to only a sham operation (sham group). RESULTS: Neurological examination scores at 24, 48, and 72 hours showed that MK-801 and drug-only piglets were significantly worse than the controls. Pathological examination of the brains at 72 hours showed significantly greater damage in the brains of the MK-801 and control pigs relative to the sham and drug-only groups. No differences were found between the control and the MK-801 groups. No differences were found between the sham and drug-only groups. CONCLUSIONS: MK-801, at a dose of 3 mg/kg, causes neurological dysfunction in piglets lasting at least 72 hours, but neither causes brain damage nor ameliorates the effects of hypoxic-ischemic injury to the brain of the newborn pig.

Animals↗