Interactions between homocyst(e)ine and nitric oxide during acute submaximal exercise in adult males

Experimental studies investigating the effects of exercise on plasma total homocyst(e)ine (H[e]) levels in humans are almost non-existent. H(e) has been demonstrated to represent an independent risk factor for cardiovascular disease. The exact mechanism through which H(e) exerts its effects on the arteries is unknown but it is thought to involve nitric oxide (NO). The present study was designed to assess the effects of acute submaximal exercise on H(e) while levels of NO inhalation were manipulated using an air-filter mask. The study was completed by seven male volunteers, aged 21.6+/-1.3 yr (X+/-SD), VO2max: 48.6+/-7.6 mL x kg(-1) x min(-1). During two separate occasions the subjects performed a 1-hour bout of submaximal exercise on a stationary cycle ergometer at 60% of their VO2max. The two trials were completed in random order (with and without mask). Data were collected before (PRE) and after (POST) the acute exercise bouts. Plasma H(e) was directly measured by HPLC and NO by quantifying the enzymatic oxidation to nitrite (NO2-) & nitrate (NO3-). Mean H(e) concentrations were 10.89+/-2.05 nmol/mL (PRE) & 11.21+/-1.81 nmol/mL (POST) and were not significantly altered by submaximal exercise. When wearing a mask, the correlation of the PRE/POST H(e) differences with the PRE/ POST differences in NO3- were 0.77 (P=0.07). No correlation was found between either H(e) and NO2- or between NO2- and NO3-. However, a significant correlation (r= - 0.86, P= 0.03) was also observed between H(e) and NO2- but only for the post-exercise values when wearing a mask. The results suggest that: (1) plasma H(e) levels are not affected by acute submaximal exercise; (2) there is insufficient evidence to support the view that plasma H(e) levels are being mediated by NO during either rest or exercise.

Mutational hotspot in the human biotinidase gene causes profound biotinidase deficiency

Biotinidase deficiency is an autosomal recessive inherited disorder that is characterized by neurological and cutaneous symptoms. Biotinidase-deficient children cannot recycle endogenous biotin, an essential water-soluble B vitamin. Biotin is covalently attached to epsilon-amino groups of lysyl residues of four carboxylases. These carboxylases are subsequently degraded to biocytin (biotin-epsilon-lysine). Biotinidase cleaves biocytin to biotin and lysine, thereby completing the biotin cycle. The symptoms of biotinidase deficiency can be resolved or prevented by treatment with biotin. Therefore, it is important that biotinidase deficiency is diagnosed early so that permanent neurological damage can be prevented. Many states and countries currently perform newborn screening for biotinidase deficiency. We have recently isolated and characterized the cDNA for normal human biotinidase and localized the gene to chromosome 3p25 (ref. 9). We have now identified the first mutation that causes profound biotinidase deficiency. It occurs in a distinct region of the gene that encodes the putative signal peptide. Fifty percent of symptomatic children studied have a 7-bp deletion coupled with a 3-bp insertion in at least one of their alleles of the biotinidase gene. This mutation appears to be a common cause of biotinidase deficiency in symptomatic children.

Mental retardation and Ullrich-Turner syndrome in cases with 45,X/46X,+mar: additional support for the loss of the X-inactivation center hypothesis

Four cases having mosaicism for a small marker or ring [45,X/46,X,+mar or 45,X/46,X,+r] chromosome were ascertained following cytogenetic studies requested because of minor anomalies (cases 1, 3, and 4) and/or short stature (cases 2 and 4). While all 4 cases had traits typical of Ullrich-Turner syndrome (UTS), cases 1, 3, and 4 had manifestations not usually present in UTS, including unusual facial appearance, mental retardation/developmental delay (MR/DD) (cases 3 and 4), and syndactylies (case 1). The facial appearances of cases 1 and 3 were similar yet distinct from that of case 4. Using fluorescence in situ hybridization (FISH), each of the markers in these 4 cases was identified as having been derived from an X chromosome. The level of mosaicism for the mar/r(X) cell line in these cases varied from 70% (case 1) to 16% (case 4) but was not apparently correlated with the presence of MR/DD. Replication studies demonstrated a probable early replication pattern for the mar/r(X) in cases 1, 3, and 4, while the marker in case 2 was apparently late replicating. To date, 41 individuals having mosaicism for a small mar/r(X) chromosome have been described. Interestingly, most of the 14 individuals having a presumedly active mar/r(X) demonstrated clinical findings atypical of UTS, including abnormal facial changes (11) and MR/DD (13). MR was noted most frequently in those cases having at least 50% mosaicism for the marker or ring. In contrast, atypical UTS facial appearance or MR/DD was not noted in 14 of the 16 cases with UTS who carried a probable late replicating marker or ring. In conclusion, although the phenotype of 45,X/46,X,mar/r(X) individuals appears to be influenced by the genetic content and degree of mosaicism for the mar/r(X), the most significant factor associated with MR/DD appears to be the activity status of the mar/r(X) chromosome. Thus, our 4 cases provide further support for the hypothesis that a lack of inactivation of a small mar/r(X) chromosome may be a factor leading to the MR and other phenotypic abnormalities seen in this subset of individuals having atypical UTS.

Human serum biotinidase. cDNA cloning, sequence, and characterization

Biotinidase (EC 3.5.1.12) catalyzes the hydrolysis of biocytin, the product of biotin-dependent carboxylase degradation, to biotin and lysine. Biotinidase deficiency is an inherited metabolic disorder of biotin recycling that is characterized by neurological and cutaneous abnormalities, and can be successfully treated with biotin supplementation. Sequences of tryptic peptides of the purified human serum enzyme were used to design oligonucleotide primers for polymerase chain reaction amplification from human hepatic total RNA to generate putative biotinidase cDNA fragments. Sequence analysis of a cDNA isolated from a human liver library by plaque hybridization with the largest cDNA probe revealed an open reading frame of 1629 bases encoding a protein of 543 amino acid residues, including 41 amino acids of a potential signal peptide. Comparison of the open reading frame with the known biotinidase tryptic peptides and recognition of the expressed protein encoded by this cDNA by monoclonal antibodies prepared against purified biotinidase demonstrated the identity of this cDNA. Southern analyses suggested that biotinidase is a single copy gene and revealed that human cDNA probes hybridized to genomic DNA from mammals, but not from chicken or yeast. Northern analysis indicated the presence of biotinidase mRNA in human heart, brain, placenta, liver, lung, skeletal muscle, kidney, and pancreas.

Effects of various anti-T cell receptor antibodies on the development of type II collagen-induced arthritis in mice

Recent genetic studies of David and coworkers suggest that subsets of T cells utilizing specific V beta TcR genes may play important roles in the susceptibility to collagen-induced arthritis (CIA). Hence, in vivo depletion of such T cell subsets may significantly affect the development of CIA. To address this possibility, we first examined the effects of in vivo treatments with various monoclonal antibodies (mAbs) that are specific for particular TcR V beta families on the induction of CIA. Results presented in this study demonstrated that treatments with either anti-V beta 6, anti-V beta 8 or anti-V beta 11 did not suppress the development of arthritis in collagen-immunized mice. While combined treatments with these V beta specific mAbs which resulted in the in vivo elimination of V beta 6+, V beta 8+ and V beta 11+ T cells were not very effective in preventing the onset of CIA, the severity of the arthritic disease was somewhat reduced in animals that had received the triad of anti-V beta mAbs. By contrast, depletion of T cells expressing the alpha beta receptors by in vivo treatments with a pan anti-alpha beta mAb significantly decreased the incidence of CIA. Therefore, although an effect on the development of CIA was achieved by in vivo treatments with a mAb that detects all alpha beta + T cells, the elimination of only a few subsets of T cells which included the V beta 6+, V beta 8+, and V beta 11+ cells did not profoundly alter the incidence of CIA.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of peritoneal insufflation to displace the small bowel during pelvic and abdominal radiotherapy in carcinoma of the cervix

Peritoneal insufflation is a technique which reliably displaces small bowel from pelvic and abdominal radiotherapy fields with the aim of reducing bowel reactions which limit the dose of radiation applied to these sites. Use of this technique in five patients undergoing radiotherapy for advanced carcinoma of the cervix, and the degree of bowel displacement resulting, dosimetry, acute reactions and tolerability of the technique are presented, with discussion of the possibility of future escalation in radiotherapy dose.

Interleukin-1 enhances the development of type II collagen-induced arthritis only in susceptible and not in resistant mice

The development of type II collagen-induced arthritis (CIA) in DBA/1 mice is readily accelerated by treatments with interleukin-1 beta (IL-1 beta). In an attempt to further characterize this IL-1 beta-mediated enhancement of CIA, we first examined the effects of IL-1 beta treatments in other "CIA-susceptible" strains and "CIA-resistant" mice. It was observed that treatments with IL-1 beta also enhanced the onset of arthritis in two B10 recombinant CIA-susceptible strains, B10.T (6R) and B10.DA, and in the SJL mice which develop CIA with a relatively low and variable incidence. On the other hand, IL-1 beta failed to augment the expression of arthritic disease in several CIA-resistant strains. We also investigated the potentiating effects of IL-1 beta in mice that were depleted of L3T4+ T cells. It was found that the ability of IL-1 beta to accelerate the development of CIA was significantly reduced in DBA/1 mice pretreated with the monoclonal anti-L3T4 antibody. In further studies, we demonstrated that the induction of CIA upon transfer with collagen-primed spleen cells was also augmented by IL-1 beta, and this enhancing effect by IL-1 beta on the adoptive transfer of CIA was associated with a significant increase in the levels of serum anti-collagen antibodies. Moreover, IL-1 beta treatments did not potentiate the induction of CIA in mice that were transferred with either collagen-immune splenic cells that were depleted of L3T4+ T cells or only T cells obtained from collagen-immunized animals. However, IL-1 beta enhanced the development of arthritis in animals that had been transferred with two subpopulations of collagen-immune cells: (i) enriched T cells and (ii) splenic cells that were depleted of L3T4+ T cells. Thus, IL-1 beta potentiated the inflammatory responses in animals that were genetically predisposed to developing arthritis. In contrast, IL-1 beta was incapable of accelerating the development of arthritis in various mouse strains that were genetically resistant to CIA. The administration of IL-1 beta also failed to potentiate the development of CIA in L3T4-deficient mice or in animals transferred with collagen-primed spleen cells that were depleted of L3T4+ T cells. These results indicate that IL-1 beta readily accelerates the induction of arthritis when the disease is present, but that IL-1 beta is incapable of promoting the expression of the arthritis in the absence of underlying disease.

Progressive bilateral nasal alar collapse: a dominantly inherited trait

We describe a 47-year-old woman with progressive bilateral collapse of the alae nasi first noted at age 16 years. Her dizygotic twin daughters have similar nasal collapse beginning at age 20 years. This condition appears to be inherited as a dominant trait. Although plastic surgical correction has been successful for a phenotypically similar condition due to trauma, surgical correction must be considered cautiously in individuals with an atraumative, possibly inherited, progressive form of the disorder.

Interleukin 1 enhances the development of spontaneous arthritis in MRL/lpr mice

We previously reported that treatments with human recombinant interleukin-1 beta (rIL-1 beta) in DBA/1 mice which were suboptimally immunized with native chick type II collagen (NcII) markedly accelerated the onset of collagen-induced arthritis (CIA). In the present study, we further characterized this IL-1-mediated enhancement of murine arthritis by examining the in vivo effects of rIL-1 beta in another arthritis model, namely, the spontaneous arthritis of the MRL/lpr mouse strain. The results of these studies demonstrated that IL-1 treatments also enhanced the onset and progression of the spontaneous arthritic disease in MRL/lpr mice. A substantial proportion of the IL-1-treated MRL/lpr mice that were between 3 and 3.5 months of age exhibited swelling in either the hind or front paws. Moreover, histopathologic studies demonstrated the presence of striking alterations within the various joints of these IL-1-treated MRL/lpr mice. Such abnormalities were not detected in the non-IL-1-treated, age-matched MRL/lpr mice. Therefore, as in the experimentally induced disease of CIA, IL-1 may also be capable of contributing to the pathogenesis of the spontaneous arthritis of MRL/lpr mice.

Comparative human cellular radiosensitivity: II. The survival following gamma-irradiation of unstimulated (G0) T-lymphocytes, T-lymphocyte lines, lymphoblastoid cell lines and fibroblasts from normal donors, from ataxia-telangiectasia patients and from ataxia-telangiectasia heterozygotes

We have measured clonal survival following gamma-irradiation of unstimulated (G0) T-lymphocytes from 35 donors, of 11 T-lymphocyte cell lines, of six lymphoblastoid cell lines, and of nine primary fibroblast strains for which we have G0 T-lymphocyte material from the same donor. Amongst the G0 lymphocytes we have results from nine normal donors, from eight cord bloods, from seven ataxia-telangiectasia (A-T) patients and from nine A-T heterozygotes. Although there is some variation between samples, G0 T-lymphocytes from normal donors appear to be slightly more radioresistant than T-lymphocyte lines, with a more shouldered survival curve. From our limited sample, lymphoblastoid cell lines appear to be slightly more radiosensitive than T-lymphocytes. The overall radiosensitivity of primary fibroblasts appears to be broadly similar to that of G0 T-lymphocytes. In nine instances, five A-Ts and four A-T heterozygotes, both G0 T-lymphocytes and primary fibroblasts from the same donor were tested. In five cases there was closely similar radiosensitivity in the two cell types, but in four cases there was some discrepancy. Further work, especially with normal donors, will be required in order to establish how reliably radiosensitivity in other cell types can be predicted from that of G0 T-lymphocytes. In all cell types the hypersensitivity of A-T cells was confirmed. Furthermore, the marginally greater sensitivity of A-T heterozygotes, when compared as a group with normals, was confirmed with G0 T-lymphocytes. Our results also suggest a slightly increased radiosensitivity in G0 T-lymphocytes from some, but not all, cord blood samples.

A further assessment of factors influencing measurements of thioguanine-resistant mutant frequency in circulating T-lymphocytes

We have used the T-Lymphocyte cloning technique as a method of monitoring the human population for somatic cell mutant frequency. We present a statistical analysis of the experimental factors which may influence the observed mutant frequency. We have obtained consistently high plating efficiencies of T-cells from the mononuclear cell fraction from donor blood samples (mean of 56%, based on 123 observations from 70 individuals). Nevertheless, an inverse correlation of mutant frequency with plating efficiency was observed, and some experimental factors (serum and interleukin-2 batch, and worker) may have a significant effect on the observed mutant frequency. We discuss the difficulties that these possible effects present in establishment of a reference database and design of long-term studies. No significant effect of donor sex on mutant frequency was observed, but age (1.3% increase per year for normal adults) and smoking (56% increase over normal non-smokers) both significantly increased the mutant frequency. We discuss the utility of the assay for the monitoring of populations for heritable DNA damage, and we compare the results to those obtained with lymphocytes using other endpoints, e.g. chromosome aberrations, micronuclei and sister-chromatid exchange.

Detection of somatic mutations in man: evaluation of the microtitre cloning assay for T-lymphocytes

A method of detecting 6-thioguanine-resistant lymphocytes by the cloning of T-lymphocytes in microtitre wells is evaluated for its usefulness in population monitoring. Factors shown to affect the cloning efficiency of lymphocytes include the strain and irradiation level of the lymphoblastoid feeder cells and the use of a pre-incubation period in bulk culture without mitogenic stimulus before plating at limiting dilutions. Cord blood samples have markedly lower mutant frequencies than adult blood samples. The adult range was 8.0 X 10(-7) to 1.8 X 10(-5). Seven males and seven females aged between 23 and 47 years were sampled. No effect of sex or age was found. Individual samples which were divided at collection and treated separately did not vary from each other, but repeat samples taken at different times showed up to a 2-fold variation. The application of this method in population monitoring is discussed.