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Biomedical subjects

L Baker

Publications and source records attributed to L Baker.

At least 127 records · Page 7Linked to original sources
PubMed1990

Impaired metabolic function and signaling defects in phagocytic cells in glycogen storage disease type 1b.

Patients with glycogen storage disease (GSD) type 1b (1b), in contrast to patients with GSD type 1a (1a), are susceptible to recurrent bacterial infections suggesting an impairment in their immune system. In this study, phagocytic cell (neutrophil and monocyte) respiratory burst activity, as measured by superoxide anion generation, oxygen consumption, and hexose monophosphate shunt activity, was markedly reduced in both neutrophils and monocytes from GSD 1b patients as compared with either GSD 1a patients or healthy adult control cells. Degranulation, unlike respiratory burst activity, was not significantly different in neutrophils from GSD 1b patients as compared with controls. Both neutrophils and monocytes from GSD 1b patients showed decreased ability to elevate cytosolic calcium in response to the chemotactic peptide f-Met-Leu-Phe. In addition, calcium mobilization in response to ionomycin was also attenuated suggesting decreased calcium stores. Thus, reduced phagocytic cell function in GSD 1b is associated with diminished calcium mobilization and defective calcium stores. Defective calcium signaling is associated with a selective defect in respiratory burst activity but not degranulation.

Calcium↗
PubMed1990

Diabetic glycemic control and retinal blood flow.

The effect of strict glycemic control on retinal volumetric blood flow rate (Q) was investigated in 13 insulin-dependent diabetic patients with laser Doppler velocimetry and monochromatic fundus photography. Strict glycemic control was achieved by glucose monitoring and four daily insulin injections. Q was determined in a major retinal vein at baseline and then 5 days, 2 mo, and 6 mo after the institution of strict control. Level of retinopathy was assessed from stereocolor fundus photographs taken at baseline and 6 mo. After 6 mo of strict diabetic control, five eyes demonstrated progression (P) by one or more retinopathy levels, and eight eyes showed no progression (NP). At 5 days, there was a significant decrease in Q of 1.4 +/- 0.9 microliters/min (P less than 0.005) in NP eyes and a nonsignificant increase in Q of 1.2 +/- 1.7 microliters/min in P eyes. Changes in Q from baseline observed at 5 days were strongly correlated with changes in retinopathy level at 6 mo (r = 0.79, P less than 0.005). No significant changes in Q from baseline were observed at 2 and 6 mo. A lack of decrease in Q at 5 days was associated with the progression of retinopathy that occurs in some patients after the institution of strict glycemic control and may serve as a predictor for progression of retinopathy.

Adult↗
PubMed1989

Differences in mucosal appearances and in relapse rates in duodenal ulceration treated with sucralfate or cimetidine.

A total of 46 patients with duodenal ulcer were randomly assigned, without the knowledge of the investigators, to treatment with cimetidine 200 mg three times daily and 400 mg at night or sucralfate 1 g four times daily followed by one year of maintenance treatment with cimetidine 400 mg at night or sucralfate 1 g twice daily, respectively, in those patients with healed ulcers. The endoscopic healing rates and relapse rates during the maintenance period were similar, four relapses occurring in each group. All four relapses in the sucralfate group occurred at 12 months and only two were symptomatic. All the cimetidine relapses were symptomatic, two occurring at six months, one at nine months, and one at 12 months. Following the one year maintenance period, 13 cimetidine patients and 11 sucralfate patients were followed up for 36 months. During the first two years, nine of 13 (69 percent) cimetidine-treated and two of 11 (18 percent) sucralfate-treated patients had relapses. During the third year, three more sucralfate-treated patients and one more cimetidine-treated patient had relapses, making a total of 10 of 13 (77 percent) and five of 11 (45 percent) in the cimetidine and sucralfate groups, respectively. Duodenal biopsy specimens obtained before and after healing and after one year of maintenance were examined by light and electron microscopy. The sucralfate group showed greater improvement after one year of maintenance therapy than did the cimetidine group, although the appearances in either group were not predictive of subsequent relapse. The results show that relapses are less frequent and occur later after sucralfate therapy and also that the morphologic appearances are more normal after treatment with sucralfate than after treatment with cimetidine.

Adolescent↗
PubMed1989

Infantile autism and developmental receptive dysphasia: a comparative follow-up into middle childhood.

An interim follow-up study of a group of "higher functioning" boys with infantile autism and control group of boys with severe (receptive) developmental language disorder (or dysphasia) is reported. The boys were compared both initially and at follow-up for overall functioning in the areas of language, peer relationships, stereotyped behaviors, and disruptive public behaviors, as well as for the presence of a number of specific symptoms. In some respects, the behaviors that differentiated the groups initially did so also at follow-up, although there were important differences. Very few of the autistic boys had good language skills at follow-up, whereas nearly half of the dysphasic group were communicating well, a difference that is striking in view of the initial general similarity between the groups in terms of poor language functioning. However, some of the dysphasic children had developed greater difficulties in peer relationships. The implications for concepts of the nature of the deficit in severe receptive developmental language disorders are considered.

Autistic Disorder↗
PubMed1989

Hyperfiltration and renal disease in glycogen storage disease, type I.

A prospective study of 14 patients (ages 6 months to 33 years) with glycogen storage disease, Type I (GSD-I) was carried out in order to define the character and frequency of renal dysfunction. A marked increase in the glomerular filtration rate (GFR) was documented in virtually all subjects, with the mean GFR raised by approximately 50%, to the range of 170 ml/min/1.73 m2. While this constituted the only renal abnormality found in the younger patients, a significant increase in urinary albumin excretion was seen in three teen-aged individuals; three patients over 20 years of age exhibited frank proteinuria (2 to 8 g/day). Renal biopsy on two of the proteinuric subjects revealed focal and global glomerulosclerosis and interstitial fibrosis. Evaluation of factors known to cause an increase in GFR did not define the precise etiology for its elevation in GSD-I. These studies suggest that: (1) glomerular damage and chronic renal disease are common in older patients with GSD-I; (2) the renal injury appears to be specifically related to GSD-I and is not secondary to the treatment of the disease; and (3) the natural history of the renal lesion in GSD-I may be analogous to that seen in insulin-dependent diabetes, with a "silent" period where hyperfiltration is the only demonstrable renal abnormality, followed by evidence of increasing glomerular damage progressing from microalbuminuria to frank proteinuria.

Adolescent↗
PubMed1989

Antibodies to human immunodeficiency virus type 1 in the urine specimens of HIV-1-seropositive individuals.

Specific antibodies to human immunodeficiency virus type 1 (HIV-1) were detected in 200-fold concentrated urine samples, but none were detected in unconcentrated urine specimens, from 100 randomly selected HIV-1--seropositive individuals by enzyme-linked immunosorbent assay (ELISA) and Western blot techniques using the manufacturer's recommended procedures. Using modified methods for both the ELISA and Western blot tests, antibodies to HIV-1 have also been detected in the unconcentrated urine specimens from the same HIV-1--seropositive individuals. No difference in the frequency of antibodies to HIV-1 were found between unconcentrated and 200-fold concentrated urine samples when tested by the modified methods. HIV-1 core antigen (p24) was not detected in either the concentrated or the unconcentrated HIV-1--seropositive adult urine samples; none of these individuals showed overt clinical or laboratory evidence of renal dysfunction. The titer of the antibodies to HIV-1 found in the urine specimens was found to be parallel with the titer of antibodies to HIV-1 in the corresponding individual's serum. Further elucidation of the pathophysiology and the nature of the specific antibodies to HIV-1 observed in the urine of HIV-1--seropositive individuals is under investigation in our laboratories.

Adolescent↗
PubMed1989

Stability and natural history of DSM-III childhood diagnoses.

Follow-up or natural history outcome data for various DSM-III child and adolescent psychiatric diagnoses are presented. The data are relevant not only to our understanding of the specific disorders but also to the validity of the DSM-III diagnostic categories. "Semi-blind" psychiatric evaluations of 151 children were made as they presented to a community speech/language clinic and again approximately 4 years later. The follow-up data revealed high stability for only three diagnoses: infantile autism, attention deficit disorder with hyperactivity, and oppositional disorder. The data revealed that several of the DSM-III subcategories lacked predictive validity. This was true for the distinctions between attention deficit disorder with versus without hyperactivity; and between avoidant, separation anxiety, and overanxious disorders. Surprisingly low stability was found for conduct disorder diagnoses as were surprisingly poor prognoses for parent-child problems and adjustment disorders.

Adolescent↗
PubMed1989

Subtypes of HLA-DQ and -DR defined by DQB1 and DRB1 RFLPs: allele frequencies in the general population and in insulin-dependent diabetes (IDDM) and multiple sclerosis patients.

We have used the HLA-DQB1 gene as a Southern hybridization probe with TaqI-digested genomic DNA in a study of 600 haplotypes from unrelated individuals and have characterized HLA-DQB1 RFLP patterns associated with the DR specificities DR1-DRw10 and DN1. For six of the specificities (DR2, 4, w6, 7, w8 and 9), we have also identified subtypes (multiple DQB1 band patterns). In a previous study (Cox et al. 1988), we identified RFLPs and subtypes with a DRB1 probe. Using the present results from DQB1 RFLPs to supplement those from DRB1 RFLPs, it was possible to discriminate among all the DR specificities with the exception of a minority of DR7 and DR9 subtypes. A comparison of DQB1 and DRB1 subtypes in the same subjects showed strong linkage disequilibrium for subtypes of some but not all DR specificities. We have also determined the allele frequencies of the DQB1 subtypes in controls and in patients with insulin-dependent diabetes mellitus (IDDM) or multiple sclerosis (MS). A consideration of subtypes in patients and controls indicated that for most DR specificities, neither IDDM nor MS was more strongly associated with any of the DQB1 subtypes than with the serologically defined DR antigens. The exceptions were the DQB1 patterns corresponding to the DQw3.2 subtype of DR4 and the rarer subtype of DR2, which were found in higher frequency in IDDM patients, as has been previously reported.

Alleles↗
PubMed1989

Comparison of relapse rates and of mucosal abnormalities after healing of duodenal ulceration and after one year's maintenance with cimetidine or sucralfate: a light and electron microscopy study.

Forty six patients with endoscopically diagnosed duodenal ulceration were randomly allocated to treatment with either sucralfate 1 g qds (n = 24) or cimetidine 200 mg tds and 400 mg nocte (n = 22). When the ulcers healed, a maintenance dose of sucralfate 1 g bd or cimetidine 400 mg nocte was given for one year (or until relapse if earlier). Biopsies of duodenal mucosa adjacent to ulcer sites for light and electron microscopy were obtained before and after healing and again after one year's maintenance if the ulcer remained healed. Duodenal biopsies were also taken from 20 age and sex matched controls. Rates of healing and relapse during maintenance did not differ between the two treatments, although relapses occurred earlier with cimetidine. In the three year post-maintenance follow up period 10/13 cimetidine patients relapsed compared with four of 11 sucralfate patients (p less than 0.05), the relapses occurring significantly earlier in the cimetidine treated patients (p less than 0.05). Mucosal biopsies from both treatment groups still showed considerable abnormalities after healing. During maintenance, however, the sucralfate scores fell significantly (p less than 0.02) to near control levels unlike the cimetidine scores which remained raised at pretreatment values. The histological and ultrastructural changes were not predictive of later relapse. These findings favour the use of sucralfate in preference to cimetidine for maintenance treatment in the prevention of relapse of healed duodenal ulcers.

Adolescent↗
PubMed1988

Effect of cyclosporine and irradiation on experimental pancreatic allografts in the primate.

The present study assessed the effectiveness of cyclosporine (CSA) and subtotal marrow irradiation (TL1) alone, and CSA in combination with TL1 in a primate segmental pancreatic allotransplantation model. Continuous administration of CSA 25 mg/kg/day and 50 mg/kg/day resulted in mean graft survival of 21.5 days and 24.5 days, respectively. Administration of fractionated TL1 800 rad (8 Gy) and 1,000 rad (10 Gy) alone resulted in mean graft survival of 13.3 days and 14.5 days, respectively. Of 20 animals that received TL1 1,000 rad (10 Gy) and CSA 25 mg/kg/day orally for 5 days then 10 mg/kg/day intramuscularly indefinitely, 3 had graft survival of greater than 100 days. Likewise, of a group of 15 animals that received TL1 800 rad (8 Gy) and combined indefinite administration of CSA, 6 had graft survival of greater than 100 days. Although CSA and TL1 administration alone produced modest pancreatic allograft survival, a combination of IL1 (800 or 1,000 rad) and CSA resulted in highly significant segmental pancreatic allograft survival in the primate.

Animals↗
PubMed1988

Insulin autoantibodies at diagnosis of insulin-dependent diabetes: effect on the antibody response to insulin treatment.

Insulin autoantibodies (IAA) are frequently found in newly diagnosed untreated insulin-dependent diabetics. We evaluated whether the insulin antibody response over the first year of treatment with insulin was different in individuals with IAA v those without IAA. One hundred five previously untreated type I diabetics were randomly assigned to treatment with either pure porcine or mixed bovine/porcine insulin. Twenty-one in each group had detectable IAA at diagnosis. Percent binding rose in all patients after commencing insulin therapy and was significantly greater in those with IAA at diagnosis irrespective of the type of insulin administered. The elevated binding in the IAA positive patients at all time points was equivalent to the binding that could be attributed to the insulin autoantibodies. Two different mechanisms could explain this greater insulin antibody binding during insulin therapy in the IAA positive patients. First, there may be summation of binding due to insulin autoantibodies and binding due to insulin antibodies formed in response to the exogenous insulin. Alternatively, the insulin antibodies formed in response to exogenous insulin could replace the IAA, with those individuals positive for IAA at diagnosis having a proportionately greater antibody response to injected insulin. Irrespective of the mechanism, patients with IAA at diagnosis develop higher insulin antibody measurements when subsequently treated with exogenous insulin.

Autoantibodies↗
PubMed1988

Analysis of DR and DQ gene products of the DR4 haplotype in patients with IDDM: possible involvement of more than one locus.

Fifteen DR4-bearing haplotypes from twelve patients with insulin-dependent diabetes mellitus (IDDM) were analyzed serologically, cellularly, and biochemically. The HLA-Dw composition of these DR4-positive haplotypes was Dw4 (46%), Dw14 (22%), and Dw10 (33%). The biochemical analysis by two-dimensional electrophoresis (2D-PAGE) of the DR beta chains showed that each Dw specificity is characterized by a specific DR4 beta chain that appears to be identical in normal and diabetic individuals. Analysis of DQ beta chains in the DR4-bearing haplotypes revealed that certain Dw specificities such as Dw4 are characterized by the presence of either the DQw7 (formerly DQw3.1) or DQw8 (formerly DQw3.2) alleles, which generate the Dw4.1 or Dw4.2 subtypes, respectively. Others such as Dw14 and Dw10 are characterized by the presence of the DQw8 allele. In our sample of 12 patients the Dw4.2 (Dw4, DR4 beta I-4 DQw8) and Dw10 (Dw10, DR4 beta I-1, DQw8) subtypes were predominant. It is concluded that individual DR beta and DQ beta gene products from the DR4-bearing haplotype of IDDM patients are identical to those of normal control subjects and that Dw14 as well as Dw10 are involved in disease susceptibility. We suggest that disease susceptibility may be influenced by more than one locus within the HLA-D region.

Diabetes Mellitus, Type 1↗