PubMed Health⌕ Search

Biomedical subjects

M Sims

Publications and source records attributed to M Sims.

At least 19 recordsLinked to original sources
PubMed1997

Antibody selection against CD52 produces a paroxysmal nocturnal haemoglobinuria phenotype in human lymphocytes by a novel mechanism.

The CD52 antigen is a lymphocyte glycoprotein with an extremely short polypeptide backbone and a single N-linked glycan, and it is attached to the cell membrane by a glycosylphosphatidylinositol (GPI) anchor. Treatment of rheumatoid arthritis patients with CAMPATH-1H, a humanized monoclonal antibody against CD52, resulted, in a small number of cases, in the appearance and persistence of CD52-negative T cells. Similarly, CD52-negative B cells emerged following in vitro treatment of a CD52-positive human B cell line with CAMPATH-1H. Both the B and T CD52-negative cells were also found to be defective in surface expression of other GPI-anchored proteins. Biochemical analysis revealed a severe defect in the synthesis of a mature GPI precursor in both the B and T cell lines. Therefore the phenotype of these CD52-negative B and T cells closely resembles that of lymphocytes from patients with paroxysmal nocturnal haemoglobinuria (PNH), in which the first step of the GPI-biosynthetic pathway, i.e. synthesis of GlcNAc-phosphatidylinositol, is blocked. In all cases studied to date, this defect maps to a mutation of the phosphatidylinositolglycan class A (PIG-A) structural gene. We therefore amplified the PIG-A gene from both the GPI-negative B and T cells by PCR and determined the nucleotide sequence. No differences from the wild-type sequence were detected; therefore a classical PNH mutation cannot be responsible for the GPI-biosynthesis defect in these cell lines. Significantly, the GPI-negative phenotype of the B cells was reversible upon separation of the positive and negative cells, resulting in a redistribution to a mixed population with either CD52-positive or -negative cells, whereas populations of 100% CD52-negative T cells were stably maintained during culture. Therefore, whereas the GPI-biosynthesis deficiency in the T cell lines may be due to a mutation in another gene required by the GPI-biosynthetic pathway, the reversible nature of this block in the B cell lines suggests a less direct cause, possibly an alteration in a regulatory factor. Overall, these data demonstrate that the PNH phenotype can be generated without a mutation in the PIG-A structural gene, and thereby identify a novel mechanism for the development of GPI deficiency.

Alemtuzumab↗
PubMed1997

Coinfection with Giardia lamblia and Enterocytozoon bieneusi in a patient with acquired immunodeficiency syndrome and chronic diarrhea.

Diarrhea is an important clinical problem in immunosuppressed patients with acquired immunodeficiency syndrome (AIDS). There are numerous classical as well as emerging enteric pathogens that can produce diarrhea; however, these agents can be missed when only one method, such as microbiological examination of stool, is used for diagnosis. The endoscopic biopsy is a sensitive method for diagnosis of many viral, fungal, and parasitic infections of the gastrointestinal tract. Although only one agent is often identified in mucosal biopsies from these immunosuppressed patients, coinfection with multiple microbial agents is being increasingly recognized. Giardia infection is not as prevalent as other pathogens in patients with AIDS, but it remains an important diarrheal agent that is potentially curable. However, there have been only rare reports of coinfections with giardiasis and other infectious agents. This report describes a patient with AIDS and chronic diarrhea who had repeated negative stool examinations for ova and parasites. Light and electron microscopic examination of subsequent endoscopically obtained small intestinal biopsies revealed coinfection with two parasites, Enterocytozoon bieneusi and Giardia lamblia. Following treatment with metronidazole for giardiasis, the diarrhea persisted, but was less severe. This report also describes the diagnostic features of Giardia and Enterocytozoon infections in biopsy tissues and emphasizes the importance of identifying enteric coinfections in patients with AIDS to ensure timely and specific modes of therapy.

AIDS-Related Opportunistic Infections↗
PubMed1996

Solution structure of a biologically active cyclic LDV peptide analogue containing a type II' beta-turn mimetic.

The solution structure of cyclo-[Gly-Leu-Asp-Val-BTD] (BTD = beta-turn dipeptide) has been determined by two-dimensional 1H-NMR (nuclear magnetic resonance) spectroscopy and systematic conformational searching combined with molecular dynamics studies. The structure contains two hydrogen bonds between the Gly and Val residues, and a type I beta-turn with Leu and Asp at the (i + 1) and (i + 2) positions of the turn. The cyclic compound shows activity in a scintillation proximity assay (SPA) for the inhibition of the interaction between the integrin alpha 4 beta 1 and vascular cell adhesion molecule-1 (VCAM-I). The structure-activity relationship of the LDV sequence is discussed.

Cloning, Molecular↗
PubMed1996

Protocols for the care of external fixator pin sites.

Pin site care methods used in the UK are based on doctor/nurse preference rather than research. There is a diversity of opinion regarding the best method of pin site care, and no standardised classification of pin site problems. There is a need for further research, either a multi-centre trial or in units with a high volume of work.

Bandages↗
PubMed1994

Production of calves by transfer of nuclei from cultured inner cell mass cells.

We report here the isolation and in vitro culture of bovine inner cell mass (ICM) cells and the use of ICM cells in nuclear transfer to produce totipotent blastocysts that resulted in calves born. Of 15 cell lines represented in this study, 13 were derived from immunosurgically isolated ICM of 3 in vitro produced day 9-10 bovine blastocysts, while 2 lines were derived from single blastocysts. Approximately 70% of attempted cell lines became established cell lines when started from 3 ICMs. The ability to establish cell lines was dependent on the number of ICMs starting the line. Sire differences were noted in the ability of ICMs to establish cell lines and to form blastocysts. The cell lines were cultured as a low cell density suspension in the medium CR1aa plus selenium, insulin, and transferrin (SIT) and 5% fetal calf serum (FCS) for 6-101 days before use in nuclear transfer, at which time some had multiplied to more than 2000 cells. If allowed to aggregate, cells of established cell lines formed embryoid bodies. A total of 659 nuclear transfer clones were made by fusing the ES cells into enucleated oocytes with polyethylene glycol; 460 of these fused, based on cleavage (70%). After culture of the clones for 7 days in vitro in CR1aa/SIT/5% FCS, 109 (24%) of those fused became blastocysts. Thirty-four blastocysts were transferred into uteri of 27 cows, and 13 cows (49%) became pregnant. Four of the 13 cows gave birth to 4 normal calves. DNA typing showed the calves to be derived from the respective sires of the cell lines. The calves were derived from cultures of less than 28 days.

Animals↗
PubMed1991

Evidence for the presence of a growth factor in Dictyostelium discoideum.

Polypeptide hormones, recognized for their ability to regulate cell growth and differentiation, have been classified as growth factors. These growth factors have been extensively described in higher eukaryotic organisms and cell lines [Hedin and Westermark, Cell 37:9-20, 1984]. Here we report the identification and partial characterization of a putative growth factor present in vegetative amoebae of the cellular slime mold Dictyostelium discoideum. A mutant was selected and found to be temperature sensitive due to the absence of an extracellular protein suggestive of a growth factor. The putative growth factor (DGF) is a protein resistant to both heat and strong detergent treatment but sensitive to reducing agents. The physiological significance of DGF is as yet unknown. DGF is of interest both in relation to understanding the events which control cell proliferation in Dictyostelium and in its relationship to other known growth factors.

Dictyostelium↗
PubMed1987

Oral ciprofloxacin in resistant urinary tract infections.

Thirty-two patients (18 men and 14 women), who ranged in age from 28 to 91 years (mean, 71.2 years), with urinary tract infections caused by Pseudomonas species or other organisms resistant to trimethoprim-sulfamethoxazole were treated with 500 mg of orally administered ciprofloxacin every 12 hours. Thirty patients completed at least five days of therapy and were evaluated for efficacy. Of these, the treatment of 28 (93 percent) patients was considered successful, with urine cultures yielding negative results five to nine days after cessation of therapy. Three of these patients were found to be reinfected with their primary pathogens when culture specimens were obtained again three to four weeks later. The two patients who received treatment that was classified as having failed had urine cultures that persistently grew Pseudomonas aeruginosa. Superinfections occurred in eight patients, four with diabetes and four with underlying central nervous system disease. Adverse reactions required discontinuation of therapy in two patients. Although the rates of reinfection and superinfection were somewhat high, these patients had a high frequency of underlying diseases that predisposed them to recurrent or difficult-to-treat infections. Despite these shortcomings, ciprofloxacin is a welcome addition to the oral antibiotic regimen for the treatment of antibiotic-resistant urinary infections.

Administration, Oral↗
PubMed1986

Neonatal jitteriness of unknown origin and circulating catecholamines.

Jitteriness is a common problem affecting neonates. Although the cause can sometimes be determined by history or conventional laboratory evaluations, nevertheless, in many instances the cause of the jitteriness is unknown. To determine if either intracranial hemorrhage (ICH) or elevated catecholamines are responsible for jitteriness in neonates, we studied 34 healthy term neonates with normal hematocrits, serum glucose, Ca, Mg, Na, K and P. Thirteen of the infants had jitteriness as their only clinical problem. There were no differences in Apgar scores, birthweight, or gestational age in the two groups. Norepinephrine levels were significantly elevated in the jittery group as compared to the control group: 1276 +/- 574 vs. 914 +/- 338, p less than 0.05. Epinephrine levels were not different in the two groups. Intracranial hemorrhage was not found in any of the patients. Jittery neonates have increased sympathetic activity. What influence the increased levels have on other metabolic and hormonal systems is yet to be determined.

Humans↗
PubMed1986

Regulation of macrophage accessory cell activity by mycobacteria. II. In vitro inhibition of Ia expression by Mycobacterium microti.

In our preceding study, we showed that infection of mice with Mycobacterium microti leads to a dramatic increase in Ia expression on local inflammatory macrophage populations. However, the majority of these cells did not contain intracellular organisms. To evaluate the effect of parasitism of macrophages by M. microti, Ia-induction experiments were performed in vitro. We show here that Ia expression is increased on peritoneal macrophages treated with either crude lymphokine preparations or recombinant gamma-interferon (gamma-IFN) and that this expression is suppressed by M. microti in a dose dependent fashion. The degree of suppression varied between macrophage populations and could be achieved to a lesser extent with killed organisms. It was partially reversed with indomethacin but only poorly so at high infection levels. Inhibition of Ia expression may be of importance in the generation and maintenance of chronic infection.

Animals↗
PubMed1982

Effects of dimethylsulfoxide (DMSO) on the oxygen paradox in perfused rat hearts.

The effect of dimethylsulfoxide (DMSO) on the morphologic features of cells and cellular enzyme release was studied in Langendorf-perfused rat hearts at 37 C. Ten percent DMSO greatly reduced the magnitude of oxygen-induced creatine kinase release (O2-CK) after a 60-minute period of hypoxic perfusion. DMSO also protected cells from development of severe contracture with formation of contraction bands. A linear correlation was found between the magnitude of O2-CK release and the percentage of cells in hearts containing contraction bands. Hypertonic mannitol did not protect hearts from CK release due to the calcium paradox, although DMSO was effective in this regard. DMSO reduced contractile force of hearts and tensions caused by hypoxic contracture as measured by an intraventricular balloon. This study suggests that DMSO affords protection from O2-CK release by actions on cells other than its osmotic effects. DMSO may alter the response of injured cells to the effects of calcium ions.

Animals↗
PubMed1981

Refractoriness of both uterus and mammary gland of the cow to prostaglandin F2 alpha administration:P clinical application.

Uterine and mammary pressure changes were simultaneously measured in lactating nonpregnant cows injected (IV) with different doses (0.1 to 32.0 mg) of prostaglandin F2 alpha (PGF2 alpha). The total work of the uterus increased up to 250% of base-line value as the dose of PGF2 alpha was increased. But, a dose-response relationship was not seen in the uterus. Partial refractoriness was developed in the uterus, and total refractoriness was developed in the mammary gland. Further challenge with oxytocin (30 U) elicited significant responses in both the uterus and the mammary gland. Because of the development of refractoriness and side effects, PGF2 alpha is not recommended as a drug to be used when mechanical evacuation (free of endocrine effect) of the uterus or mammary gland (or both) is indicated.

Animals↗
PubMed1980

Obstructing gastric carcinoma complicating pregnancy.

Although gastric cancer has not been reported in association with pregnancy, the authors encountered it in a paraplegic young pregnant woman presenting with gastric outlet obstruction.Fiberoptic gastroscopy and biopsy provided the surprising tissue diagnosis. Ultrasound was helpful in assessing the size and position of the fetus. Intravenous fluid therapy and total parenteral nutrition enabled the authors to correct the negative nitrogen balance and metabolic derangement, and to improve the operative risk to both the mother and the fetus.Cesarean section delivered a viable baby. A high gastrectomy relieved the patient of her obstruction and tumor burden. Although the long-term prognosis of gastric cancer remains grim, having saved the mother and the baby through such an ordeal is a rewarding experience.

Adult↗
PubMed1979

Mastitis-metritis-agalactia complex in sows: effect of the dosage of oxytocin on intramammary pressure in lactating healthy sows.

The dose-response and time-response relationships between injected oxytocin and intramammary pressure were investigated in normal lactating sows. In less than 39 s after 20, 40, or 80 U of oxytocin was given (IM injection), there was a rapid initial increase in intramammary pressure (15 to 27 mm of Hg) which lasted 22 to 32 s. After this initial response, there were secondary oscillations in pressure which lasted approximately 40 minutes (20 U) and up to 60 minutes (40 or 80 U). Changes in intramammary pressure during each oscillation varied between 1 and 5 mm of Hg. Mean values for frequency and amplitude of oscillations and total work (area under the trace) were measured. Compared with response obtained after 20 U of oxytocin was given, responses obtained at the 40-U or 80-U dose level had an increased frequency (150.0% and 249.0%, respectively) and total work (36.6% and 104.4%, respectively), but not amplitude. Thus, there may be some clinical advantage in milk let-down effect when sows are given the larger doses of oxytocin (40 or 80 U). These results indicate that newborn pigs should be allowed to nurse at the same time in which oxytocin is injected.

Animals↗