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Biomedical subjects

R Brenner

Publications and source records attributed to R Brenner.

At least 91 records · Page 5Linked to original sources
PubMed1984

Methylphenidate challenge as a predictor of relapse in schizophrenia.

Although neuroleptics are the major treatment for schizophrenia, there are no effective measures to determine the appropriate or necessary length of neuroleptic maintenance. To test the ability of a psychostimulant challenge to predict relapse following neuroleptic withdrawal, the authors administered methylphenidate and placebo infusions to 11 stable schizophrenic outpatients who had been on a neuroleptic maintenance regimen for at least 6 months. Patients withdrawn from neuroleptics were followed until relapse. All three patients with a positive response to methylphenidate challenge relapsed in 1 to 7 weeks; one of seven negative responders relapsed at week 21. Differences in relapse rates (p = .033) and survival time (p = .005) between negative and positive responders were significant.

Adult↗
PubMed1983

Dexamethasone suppression tests in patients with panic disorder.

Dexamethasone suppression tests were given to 10 patients with panic disorder and 22 depressed patients. All patients with panic disorder were normal suppressors, and nine depressed patients were nonsuppressors. The mean cortisol levels of the two groups differed significantly.

Adult↗
PubMed1981

Isotachophoresis for the determination of oxalate in unprocessed urine.

The principle of isotachophoresis has been used to develop a simple, specific and sensitive analytical procedure for the determination of oxalate in unprocessed urine. Analytical conditions were optimized. The accuracy and precision of the method were estimated. The specificity was checked with oxalate decarboxylase. Separation of oxalate from a number of organic acids was achieved. The influence of factors such as storage, calcium concentration, pH or ionic strength was examined. The 24-h urine excretion rates for healthy children, healthy adults and for patients with idiopathic stone formation were established. Lower absolute excretion rates were found in children and females. Urinary oxalate/creatinine ratios were higher in children than in adults. The mean oxalate excretion in 24-h urines of adult healthy individuals was 413 +/- 150 mumol per 24 h per 1.73 m2 (range 195-732). The mean oxalate/creatinine ratio was 0.033 +/- 0.011 (range 0.018-0.065).

Adult↗
PubMedDate not supplied

Acute mitral regurgitation due to chordal rupture in a patient with neonatal Marfan syndrome caused by a deletion in exon 29 of the FBN1 gene.

The neonatal Marfan syndrome is an autosomal dominantly inherited disease with an extremely poor prognosis. This report gives a clinical and echocardiographic description of an infant with a mutation in exon 29 of the fibrillin-1 gene (FBN1), a region in which this severe form of Marfan syndrome seems to cluster. The infant died at the age of 3 months due to severe acute mitral regurgitation leading to intractable heart failure.

Acute Disease↗
PubMedDate not supplied

The effect of anxiety and depression on completion/withdrawal status in patients admitted to substance abuse detoxification program.

A large proportion of patients entering substance abuse treatment carry psychiatric diagnoses, and some studies have found that those with psychopathology are more likely to withdraw before treatment is completed. We performed a prospective study of patients entering an inpatient substance abuse detoxification program to determine if the degree of anxiety and/or depression correlated with higher dropout rates. On entry to the unit, all patients were administered the Hamilton Rating Scales for Depression and Anxiety. Of the 148 patients studied, 97 (65.5%) completed treatment and 51 (34.5%) withdrew prematurely. There were no significant differences in Hamilton Depression and Anxiety Rating Scale scores between completers and withdrawers. This was true for the total study population, as well as for subgroups of patients based on primary drug abused (heroin or cocaine). Although anxiety and depression are common in substance abusers, we were unable to detect differences on validated anxiety and depression rating scales between those completing and those withdrawing from substance abuse detoxification.

Adult↗
PubMedDate not supplied

Identification of fifteen novel mutations in the tissue-nonspecific alkaline phosphatase (TNSALP) gene in European patients with severe hypophosphatasia.

Hypophosphatasia is an inherited disorder characterised by defective bone mineralisation and deficiency of serum and tissue liver/bone/kidney alkaline phosphatase (L/B/K ALP) activity. We report the characterisation of tissue-nonspecific alkaline phosphatase (TNSALP) gene mutations in a series of 13 European families affected by perinatal, infantile or childhood hypophosphatasia. Eighteen distinct mutations were found, only three of which had been reported previously in North American and Japanese populations. Most of the 15 new mutations were missense mutations, but we also found two mutations affecting donor splice sites and a nonsense mutation. A missense mutation in the last codon of the putative signal peptide probably affects the final maturation of the protein. Despite extensive sequencing of the gene and its promotor region, only one mutation was identified in two cases, one of which was compatible with a possible dominant effect of certain mutations and the putative role of polymorphisms of the TNSALP gene. In 12 of the 13 tested families, genetic diagnosis was possible by characterisation of the mutations or by use of polymorphisms as genetic markers. Hypophosphatasia diagnosis was assigned in two families where clinical, laboratory and radiographic data were unclear and prenatal diagnosis was performed in one case. The results also show that severe hypophosphatasia is due to a very large spectrum of mutations in European populations with no prevalent mutation and that genetic diagnosis of the disease must be performed by extensive analysis of the gene.

Alkaline Phosphatase↗
PubMedDate not supplied

[Osteogenesis imperfecta. New viewpoints on principles, clinical aspects and therapy].

Recently osteogenesis imperfecta has attracted much interest both of scientists and clinicians. Modern protein biochemistry and molecular biology have provided evidence that disturbed type I collagen synthesis is involved in the pathogenesis of the disease. Structural defects in the corresponding collagen genes have been identified in some cases, whereas others possibly are due to developmental defects leading to the persistence of a fetal state in collagen biosynthesis. A new clinicogenetic classification of the disease has brought a better understanding of the variable clinical course of the disease. Intramedullary telescopic rodding has proved to be a valuable orthopedic technique for the prevention and correction of fractures and deformities of long bones leading to successful rehabilitation of even severely affected patients.

Collagen↗
PubMedDate not supplied

Increased cell surface expression of receptors for transforming growth factor-beta on osteoblasts from patients with Osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a heritable connective tissue disorder usually characterized by either a reduction in the production of normal collagen I or the synthesis of abnormal collagen. The variability in the clinical phenotype is not in each case sufficiently explained by the underlying mutation in the collagen I genes. Also, biochemical differences between mutant collagen from different tissues suggest additional regulatory mechanisms possibly involved in matrix deposition and maturation, two processes in which transforming growth factor-beta (TGF-beta) plays an important role. We, therefore, studied the cell surface expression and functional properties of TGF-beta receptors I, II and III on osteoblasts from a group of OI patients compared to healthy controls. Receptor number and affinity were determined by Scatchard analysis of binding data and TGF-beta receptor II gene expression was assessed by RT-PCR. Ligand-induced downregulation of TGF-beta receptors was analyzed to demonstrate the dynamic response to exogenous stimuli. All experiments were performed in parallel in human osteoblastic cells from OI patients and from age-matched controls. TGF-beta receptors I, II and III (betaglycan) were present on osteoblasts from both healthy donors and OI patients. The receptor numbers were significantly higher (29,000 per cell) on OI osteoblasts than on age-matched control osteoblasts (12,000 per cell) in spite of similar steady state levels for TGF-beta receptor II mRNA in OI and control cells. Furthermore, receptor affinity was not significantly different in OI osteoblasts (181 vs. 177 nM(-1)), and the receptor number did not depend on the culture substrate. With respect to dynamic adaption, ligand-induced downregulation of TGF-beta receptors was reduced in OI osteoblasts. In conclusion, the human osteoblastic cells from patients with OI investigated all have an elevated number of cell surface receptors for TGF-beta, without any evidence for a transcriptional regulation of TGF-beta receptor II. On the functional level, there is some evidence for an impaired adaptive behavior of receptor presentation, whereas receptor affinity is unchanged.

Cells, Cultured↗
PubMedDate not supplied

Serum iron, zinc, copper, selenium, and bromide concentrations after coronary bypass operation.

The effect of surgical trauma on serum trace elements was studied in 10 patients undergoing coronary bypass surgery. After the initial decrease due to the hemodilution during operation serum iron, zinc, copper and selenium remained depressed for the immediate postoperative period. Zinc was still at significantly lower level 2 months after the operation. Low serum iron values were also observed. Changes in trace element concentrations were parallel with changes in the concentrations of their transport and binding proteins in the serum. The multielemental technique also measured nonessential bromide, which returned to initial levels in 7 days. Effects of trauma on metabolism, acute phase reaction with redistribution of zinc and copper and losses via increased urinary excretion explain the above changes. Development of a subclinical deficiency of zinc and possibly iron is suggested by the persistence of low serum levels during recovery after operation.

Aged↗