Dose response, coasting, and differential fiber vulnerability in human toxic neuropathy: a prospective study of pyridoxine neurotoxicity.

We administered either 1 or 3 g/d of pyridoxine (vitamin B6) to five healthy volunteers and repeatedly followed serum pyridoxal phosphate levels, clinical symptoms and signs, quantitative sensory thresholds (QSTs), and sural nerve electrophysiology. Pyridoxine was discontinued at the first sign of either clinical or laboratory abnormality. In all subjects, sensory symptoms and QST abnormalities occurred concurrently. Subjects receiving higher doses became symptomatic earlier than low-dose subjects. Elevation of thermal QSTs preceded or exceeded that for vibration in the three low-dose subjects; vibration and thermal QST became abnormal simultaneously in the higher-dose subjects. A reduction in the amplitude of the sural sensory potential lagged behind QST changes in two of three subjects. Symptoms continued to progress ("coasting") for 2 to 3 weeks despite stopping pyridoxine administration and the return of serum pyridoxal phosphate levels to normal. This study suggests that (1) there is a clear dose-percent relationship for pyridoxine-induced neuropathy, (2) QST is a sensitive measurement for detecting early peripheral neuropathy; QST abnormalities may precede changes in nerve conduction studies, (3) coasting appears unrelated to persistently elevated blood levels of the toxin, and (4) a dose-dependent vulnerability may exist among nerve fibers of different caliber when exposed to an axonal toxin, such as pyridoxine.     

Surgical indications status in ileus using a simple clinical index

Based on a retrospective analysis of a group of patients with ileus disease in regard of the indication for operative intervention an "ileus index" was created which is derived from simple clinical and radiological findings and laboratory data. Prospective evaluation of this index showed its effectiveness in separating patients who had to undergo an emergency operation from those who could be operated electively after preceding diagnostic procedures or could be treated conservatively.     

In vitro studies on the effect of delaminated a-C:H film fragments on bone marrow cell cultures

Amorphous hydrogenated carbon (a-C:H) films have many outstanding properties required for a protective coating material on load bearing medical implants. Recently, titanium doped a-C:H films have been evaluated regarding their effects on bone marrow cell cultures. But many materials that are well-tolerated in bulk form are able to induce toxic reaction if present particulate form. In order to further assess biocompatibility aspects of these two coatings, film delamination has been mimicked in exposure to fluids. In the present study, particles from a-C:H, a-C:H/Ti and a-C:H-a-C:H/Ti bilayer films were added to bone marrow cell cultures in vitro. The results showed that plain a-C:H and to a certain extent a-CH/Ti particles were inert. Both kinds of particles did not significantly stimulate the osteoclast-related enzyme tartrate resistant acid phosphatase (TRAP). A slight increase in cell proliferation and total culture TRAP was found in cultures treated by a-C:H-a-C:H/Ti bilayer films. Latter effect can probably be traced back by the relative high percentage of small particles of a size of around 2 microm. However, if corrected by the cell number also no differences between particle-treated and untreated control cultures could be found, indicating the absence of a toxic effect from delaminated a-C:H coatings.     

Small bowel transplantation in a child. Morphologic, immunohistochemical, and clinical results

A small bowel transplant was performed on a five-year-old boy with a short bowel syndrome. The donor was the child's mother. Despite immunosuppressive therapy, the transplant was acutely rejected and had to be explanted on the twelfth day. Morphologic and immunohistochemical investigations on subsequent biopsies taken from the small bowel transplant were carried out. Besides typical changes in epithelial cells and the presence of T-cell infiltrates and Ig-deposits in vessels, many macrophages were seen. The submucosa in particular was invaded before rejection by numerous macrophages with positive results of antimonocyte/macrophage antibodies Ki-M6 and Ki-M7. The number of the macrophage antibodies Ki-M6 and Ki-M7. The number of the monocyte/macrophage cells and the immunohistochemical characteristics of the same may be important parameters for monitoring small bowel transplantations.     

Combination of WAGR and Potocki-Shaffer contiguous deletion syndromes in a patient with an 11p11.2-p14 deletion

Aniridia, Wilms tumor, genitourinary abnormalities, growth and mental retardation are the cardinal features of the WAGR 11p13 deletion syndrome. The Potocki-Schaffer syndrome or proximal 11p deletion syndrome (previously DEFECT11 syndrome) is a contiguous gene syndrome associated with deletions in 11p11.2, principal features of which are multiple exostoses and enlarged parietal foramina. Mental handicap, facial dysmorphism and craniosynostosis may also be associated. We report a patient with combined WAGR and Potocki-Shaffer syndromes, and obesity. She presented with aniridia, cataract, nystagmus, corneal ulcers and bilateral congenital ptosis. A left nephroblastoma was detected at 15 months. Other features included moderate developmental delay, growth deficiency, facial dysmorphism, multiple exostoses and cranial lacunae. High-resolution and molecular cytogenetics confirmed a del(11)(p11.2p14.1) deletion with a proximal breakpoint between the cosmid DO8153 and the BAC RP11-104M24 to a distal breakpoint between cosmids CO8160 (D11S151) and F1238 (D11S1446). The deletion therefore includes EXT2, ALX4, WT1 and PAX6. This case appears to be the second patient reported with this combined deletion syndrome and confirms the association of obesity in the WAGR spectrum, a feature previously reported in four cases, and for which the acronym WAGRO has been suggested. Molecular and follow-up data on the original WAGRO case are briefly presented.     

X-linked dominant chondrodysplasia with platyspondyly, distinctive brachydactyly, hydrocephaly, and microphthalmia

We describe a family with an X-linked dominant chondrodysplasia. Four males and six females were affected through four generations. Identification of skeletal abnormalities and hydrocephaly during the pregnancy of three male fetuses led to termination of the pregnancies. A fourth affected male died at 6 days of life. The four patients had chondrodysplasia, hydrocephaly, and facial features with microphthalmia. Radiographs showed severe platyspondyly and various bone abnormalities including a distinctive metaphyseal cupping of the metacarpals, metatarsals, and phalanges. The affected females were less affected and showed small stature, sometimes associated with body asymmetry and mild mental retardation. This condition appears to be a previously unrecognized X-linked dominant chondrodysplasia.     

Gender and smoking-related risk reduction of periodontal disease with variant myeloperoxidase alleles

Myeloperoxidase (MPO) is an oxidative enzyme expressed in polymorphonuclear leukocytes. It is involved in the defence against periodontal bacteria, and is also able to mediate inflammatory tissue destruction in periodontal disease. A G/A polymorphism in the promoter region of the MPO gene at position -463 has been assumed to exert profound effects on the expression of the enzyme. It is the aim of this study to evaluate whether this polymorphism may influence the risk of periodontal diseases. A total of 3148 subjects were randomly selected from the general population in the SHIP study (Study of Health in Pomerania). Periodontal status, health-related and socio-economic items were assessed. All subjects aged 40-60 years (n = 1103) were included in this study, and 1083 genotyped for the MPO -463 G/A polymorphism by PCR and RFLP methods. The genotype frequencies determined were homozygous wild type G/G 65.9% (95% CI 63.5-68.6), heterozygous A/G 31.4% (28.8-34.4), and homozygous variant A/A 2.7% (2.0-3.8). Only female subjects have a significantly reduced risk of severe periodontal disease when bearing the variant genotypes A/G or A/A. In female subjects the reduction in periodontal risk was significant for non-smokers (OR = 0.48; 95% CI 0.23-0.96); the smoke-related increase in risk was also reduced (OR = 0.50; 95% CI 0.22-1.10). When adjusted for age, smoking, and education the odds ratios were calculated as 0.52 (P = 0.01) and 0.97 (P = 0.90) for female and male subjects, respectively. The results of this study confirm the assumption that the MPO -463A allele variants are protective in the pathogenesis of periodontal diseases. This holds true only with women but not with men. The results are discussed with respect to the known influences of sexual hormones on MPO activity.     

Efficiency of the ortho VITROS assay for detection of hepatitis C virus-specific antibodies increased by elimination of supplemental testing of samples with very low sample-to-cutoff ratios

The clinical significance of specimens with low sample-to-cutoff (S/Co) ratios in the Ortho VITROS chemiluminescence assay (CIA) for detection of antibodies to hepatitis C virus (HCV) was evaluated. In one study of 482 CIA-reactive samples, none of the 83 samples with S/Co ratios of < 5 was HCV RNA positive. In a subsequent study, 332 samples with S/Co ratios of between 1 and 20 were tested with the recombinant immunoblot assay (RIBA). None of the 163 samples with S/Co ratios of < 5 was RIBA positive, 83% were RIBA negative, and 28 samples (18%) were RIBA indeterminate. HCV RNA and/or clinical evidence of hepatitis was not found in the 27 indeterminate cases examined. These results show that over 99% of samples with very low S/Co ratios (< or = 5) have no evidence of HCV infection. Therefore, we suggest that the HCV antibody testing algorithm for the VITROS assay might be modified to eliminate supplemental testing of samples with very low S/Co ratios.     

Disruption of the gene homologous to mammalian Nramp1 in Mycobacterium tuberculosis does not affect virulence in mice

Natural-resistance-associated macrophage protein 1 (Nramp1) is a divalent cation transporter belonging to a family of transporter proteins highly conserved in eukaryotes and prokaryotes. Mammalian and bacterial transporters may compete for essential metal ions during mycobacterial infections. The mycobacterial Nramp homolog may therefore be involved in Mycobacterium tuberculosis virulence. Here, we investigated this possibility by inactivating the M. tuberculosis Nramp1 gene (Mramp) by allelic exchange mutagenesis. Disruption of Mramp did not affect the extracellular growth of bacteria under standard conditions. However, the Mramp mutation was associated with growth impairment under conditions of limited iron availability. The Mramp mutant displayed no impairment of growth or survival in macrophages derived from mouse bone marrow or in Nramp1(+/+) and Nramp1(-/-) congenic murine macrophage cell lines. Following intravenous challenge in BALB/c mice, counts of parental and Mramp mutant strains were similar in the lungs and spleens of the animals at all time points studied. These results indicate that Mramp does not contribute to the virulence of M. tuberculosis in mice.     

Analysis of tetanus toxin peptide/DR recognition by human T cell receptors reconstituted into a murine T cell hybridoma

We have previously reported that human T cell receptors (TcR) selected in the class II-restricted (HLA-DRB1*1302) response to a tetanus toxin peptide (tt830-843) frequently used the Vβ2 germ-line segment which paired with several Vα segments and that the putative CDR3 of both α and β chains showed remarkable heterogeneity. To analyze the structural basis for recognition of the tt830-843/DR complex, five of these TcR were reconstituted into a murine T cell hybridoma, 58 α^?β^?, by expressing the human α and β variable regions joined to the mouse α and β constant regions, respectively. The chimeric TcR, expressing the same Vβ germ-line segment (Vβ2), two expressing Vα21.1, twoVα17.1 and one Vα8.1 were shown to have the expected antigen specificity and DR restriction. Two lines of evidence suggested that the putative CDR3, although not conserved in these TcR, played a key role in recognition. First, two TcR with identical V germ-line segments but distinct CDR3 showed large differences in their capacity to react with the ligand. Second, interchanging the α and β chains from tt830-843/DR1302-specific TcR which differed in their CDR3 sequences invariably led to loss of recognition. We also asked whether germ-line Vα17.1 could functionally replace Vα21.1, as they appear to be related in their primary sequence. However, as in the case of CDR3 exchanges, Vα replacement abrogated TcR reactivity. Taken together, these data underline the fine interdependence of the structural components of the TcR binding site in defining a given specificity. Four of the TcR studied displaying promiscuous recognition were also tested against different DR alleles and site-directed mutants. The results of these experiments suggested that, in spite of their structural heterogeneity, anti-tt830-843 TcR may have a similar orientation with respect to the peptide/DR complex. The reconstitution system described herein should represent a valuable tool for detailed studies of human TcR specificity.