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Biomedical subjects

M Peters

Publications and source records attributed to M Peters.

At least 379 records · Page 21Linked to original sources
PubMed1987

Survival of cryopreserved isolated adult human pancreatic islets of Langerhans.

Human islets of Langerhans were isolated from the pancreata of 13 adult organ donors, cultured for 24 h, cryopreserved, stored in liquid nitrogen at -196 degrees C for 6-88 days, thawed, and then cultured again. The number of islets recovered after this procedure was 80% of that present at the beginning. The viability of cultured/cryopreserved islets was then compared with that of islets from the same donor cultured for 24 hr, and was assessed by supravital staining, insulin response to glucose, and survival after implantation under the kidney capsule of nude rats. Supravital staining showed more nonviable cells in cryopreserved islets than in their cultured counterparts. Significant response to glucose was seen before and after cryopreservation in 2 of 4 sets of islets. Xenografts of 200 cultured islets (from 13 donors) were implanted in 15 nude rats under the kidney capsule, and a further 15 rats had cryopreserved islets (from the same 13 donors) similarly implanted beneath the kidney capsule. Two weeks later tissue was visible at the site of implantation in all 30 rats. Histological examination of both groups showed the tissue to have the morphology of islets, confirmed by immunohistochemical chemical localization of insulin. The insulin content of kidneys bearing 200 cultured islets was 7.88 +/- 1.6 mU (n = 13) versus 6.84 +/- 1.43 mU (n = 13) for kidneys bearing cryopreserved islets. Thus this technique for cryopreservation of isolated adult human islets enables a high recovery of endocrine tissue that survives after transplantation to nude rats, but some evidence of damage was apparent from insulin secretion studies and electron-microscopic studies.

Animals↗
PubMed1987

Nucleotide sequence analysis of the gene encoding the Deinococcus radiodurans surface protein, derived amino acid sequence, and complementary protein chemical studies.

The complete nucleotide sequence of the gene encoding the surface (hexagonally packed intermediate [HPI])-layer polypeptide of Deinococcus radiodurans Sark was determined and found to encode a polypeptide of 1,036 amino acids. Amino acid sequence analysis of about 30% of the residues revealed that the mature polypeptide consists of at least 978 amino acids. The N terminus was blocked to Edman degradation. The results of proteolytic modification of the HPI layer in situ and Mr estimations of the HPI polypeptide expressed in Escherichia coli indicated that there is a leader sequence. The N-terminal region contained a very high percentage (29%) of threonine and serine, including a cluster of nine consecutive serine or threonine residues, whereas a stretch near the C terminus was extremely rich in aromatic amino acids (29%). The protein contained at least two disulfide bridges, as well as tightly bound reducing sugars and fatty acids.

Amino Acid Sequence↗
PubMed1987

Psychiatric complications of long-term interferon alfa therapy.

Ten (17%) of 58 patients with chronic viral hepatitis treated with a four- to 12-month course of recombinant human interferon alfa developed psychiatric side effects. The psychiatric side effects fell into three categories: an organic personality syndrome characterized by irritability and short temper; an organic affective syndrome marked by extreme emotional lability, depression, and tearfulness; and a delirium marked by clouding of consciousness, agitation, paranoia, and suicidal potential. These psychiatric side effects appeared after one to three months of therapy, usually improved within three to four days of decreasing the dose of interferon alfa, and invariably resolved once therapy was stopped. The organic personality and affective syndromes tended to occur in patients who received the highest dose of interferon alfa, who had relatively mild hepatitis, and who lost weight during interferon treatment. Delirium tended to occur in patients with severe hepatitis who had previous evidence of organic brain injury or dysfunction or previous drug and alcohol abuse. Failure to recognize these side effects quickly and to treat them with supportive therapy and modification of the dose of interferon alfa could result in limitation of therapy and serious personal and interpersonal consequences.

Adult↗
PubMed1986

Treatment of chronic non-A,non-B hepatitis with recombinant human alpha interferon. A preliminary report.

We treated 10 patients who had chronic non-A,non-B hepatitis with recombinant human alpha interferon in varying doses (0.5 to 5 million units) daily, every other day, or three times weekly for up to 12 months. In 8 of the 10 patients, elevated serum aminotransferase levels decreased rapidly during therapy and eventually fell into the normal or nearly normal range. In two of these patients, the interferon therapy was stopped after four months, and in both cases, a prompt return of aminotransferase activities to pretreatment values occurred. Prolonged treatment was associated with a sustained improvement in aminotransferase levels; in three cases, biopsy specimens obtained after one year of therapy showed marked improvement in hepatic histology, even though low doses of alpha interferon had been used. These preliminary findings, although not adequately controlled, suggest that long-term, low-dose alpha interferon therapy may be effective in controlling the disease activity in some patients with chronic non-A,non-B hepatitis. A prospective controlled trial is now needed to assess the role of interferon therapy in this disease.

Adult↗
PubMed1986

Effect of interferon-alpha on immunoglobulin synthesis by human B cells.

We have investigated the effect of human recombinant interferon-alpha (IFN-alpha) on mitogen-induced immunoglobulin (Ig) production by peripheral blood mononuclear cells from normal individuals. Low concentrations (1 to 100 IU/ml) of IFN-alpha enhanced pokeweed mitogen-stimulated Ig production. In contrast, high concentrations of IFN-alpha (10(5) IU/ml) suppressed pokeweed mitogen-induced Ig production. Irradiation of T cells did not ablate the high dose suppression, indicating that suppression was not due to a radiation-sensitive T cell. Kinetic experiments revealed that IFN-alpha needed to be added to 10 day cultures within the first 72 hr for either enhancement or suppression to be noted. Preincubation of purified B cells with IFN-alpha suppressed Ig production as completely as when unfractionated mononuclear cells were incubated with IFN-alpha. On the other hand, preincubation of T cells or monocytes with IFN-alpha had no effect on subsequent Ig production in reconstituted mononuclear cell cultures. Mitogen-induced proliferation of purified B cells was not affected by IFN-alpha at any concentration, but Ig production by purified B cells stimulated with Staphylococcus aureus Cowan I or anti-mu and B cell differentiation factors responded to IFN-alpha with low concentration enhancement and high concentration suppression. Studies of Ebstein-Barr virus-transformed B cell lines showed that IFN-alpha caused a similar effect on the CESS line as on peripheral blood B cells, with low dose enhancement and high dose suppression of Ig production. Thus one IFN-alpha effect is to modulate Ig production, and this appears to be a direct effect on B cells. Combined with the data in the accompanying paper, the effects of IFN-alpha on B cell function are similar in vivo and in vitro.

Antibody Formation↗
PubMed1986

Immunologic effects of interferon-alpha in man: treatment with human recombinant interferon-alpha suppresses in vitro immunoglobulin production in patients with chronic type B hepatitis.

The effect of human recombinant interferon-alpha on lymphocyte proliferation and differentiation was studied in 18 patients with chronic type B hepatitis who were participating in a randomized controlled trial of interferon-alpha therapy. Peripheral blood mononuclear cells (PBMC) were obtained by lymphopheresis before and during a 4 mo course of interferon. Pokeweed mitogen-induced immunoglobulin synthesis by PBMC obtained from patients before therapy was similar to that of PBMC from normal individuals. However, after 2 wk treatment with human recombinant interferon-alpha mitogen-induced immunoglobulin production was decreased by an average of 50%. Staining for cytoplasmic immunoglobulin revealed decreases that paralleled secreted immunoglobulin, indicating that interferon-alpha treatment inhibited immunoglobulin synthesis. Mixing autologous T and B cell enriched populations from before and during interferon treatment revealed that the decrease in immunoglobulin synthesis involved a defect in the B cell-enriched population. In contrast to immunoglobulin synthesis, pokeweed mitogen-induced lymphocyte proliferation was not significantly affected by in vivo administration of interferon-alpha. Thus a major effect of in vivo interferon-alpha on immunoregulation in patients with chronic type B hepatitis appears to be an inhibition of the late stages of B cell differentiation into immunoglobulin producing and secreting plasma cells.

Antibody Formation↗
PubMed1986

Successful autotransplantation of isolated islets of Langerhans in the cynomolgus monkey.

A recently described method for isolation of islets of Langerhans from the human pancreas has been adapted to the cynomolgus monkey pancreas. The mean yield of islets obtained from 13 monkey pancreata was 1319 islets per gram of pancreatic tissue (range 533-1800) and the usual purity of the preparation varied from 5 to 15 per cent islet tissue. Twelve cynomolgus monkeys underwent total pancreatectomy, preparation of islets from the excised pancreas and autotransplantation to either the spleen or the liver. Three animals received no transplant and became immediately diabetic, surviving 4-8 days. Four animals became normoglycaemic after intrasplenic islet transplantation, and survived 6 weeks, at which time splenectomy was performed with immediate onset of diabetes. Splenic vein insulin sampling confirmed the spleen as the source of insulin, and histological examination showed implanted islet tissue in all cases. Five animals became normoglycaemic after intrahepatic islet implantation. Three animals subsequently became diabetic at 4 and 5 months and two animals still have functioning grafts, the longest function being 9 months. These results suggest that in the cynomolgus monkey sufficient islets can be extracted from a single donor pancreas to reverse diabetes.

Animals↗
PubMed1986

Pilot study of recombinant human alpha-interferon for chronic type B hepatitis.

Nine patients with chronic type B hepatitis were entered into a preliminary study of recombinant, human alpha-interferon therapy. Patients received one to four courses of interferon, each consisting of a fixed dose of 18, 36, 50, 68, or 100 million units given three times a week for 2 wk. Side effects including fever, chills, fatigue, myalgias, headache, and neutropenia were common and especially severe with higher doses. Serum hepatitis B virus DNA polymerase activity fell during therapy to 15%-30% of the pretreatment levels irrespective of interferon dose, but rose to the initial level by 10 days after the course ended. During follow-up, 2 patients had a sustained clinical remission in which hepatitis B virus DNA, DNA polymerase, and hepatitis B e antigen disappeared from serum and amino-transferase activities fell to normal. One patient became hepatitis B surface antigen negative. We conclude that higher doses (50 and 68 million units) of interferon have greater side effects than lower doses (18 and 36 million units), without having any greater antiviral efficacy. Further studies should be directed at therapy with lower doses given over longer periods.

Adult↗
PubMed1986

Randomized trial of chlorambucil for primary biliary cirrhosis.

Twenty-four patients with primary biliary cirrhosis were entered into a prospective, randomized trial of chlorambucil therapy. Thirteen patients received chlorambucil (0.5-4 mg/day) and 11 patients received no therapy; all have been followed for 2-6 yr (mean, 4.1 yr). Two control but no treated patients died. Average serum bilirubin, serum aspartate aminotransferase activities, and albumin levels improved or remained unchanged in treated patients but worsened in controls. Serum alkaline phosphatase levels did not change in either group. Immunoglobulin M levels decreased and became normal in all treated patients but in only 3 control patients. Liver biopsy histology revealed an improvement in inflammatory cell infiltrate in treated patients in comparison with controls, but no significant change in degree of fibrosis or the histologic stage of disease. Side effects of therapy included bone marrow suppression necessitating discontinuation of the drug in 4 patients. These findings indicate that chlorambucil therapy may retard the progression of primary biliary cirrhosis. Whether such therapy will ultimately decrease morbidity and improve survival in this disease can only be demonstrated by large-scale, placebo-controlled trials.

Adult↗
PubMed1986

Incidence of left-handed writers and the inverted writing position in a sample of 2194 German elementary school children.

In a sample of 2194 German elementary school children, 6.9% of the females and 9.5% of the males wrote with the left hand. The proportion of left-handers writing with the inverted writing position was much higher than in comparable Canadian samples, particularly in the early grades. The higher incidence in early grades was related to the earlier introduction of cursive style writing in the German sample. There was a significant effect of writing position on the directional consistency of the letter shafts in the writing samples: noninverted writers were more inconsistent in their letter shaft orientation within and between words than inverted writers. The results stress adaptation to the technical demands of left-handed writing in the genesis of the inverted writing position, in support of recent studies (Guiard and Millerat, Neuropsychologia 22, 535-538, 1984) that come to similar conclusions.

Child↗