The biochemical composition of hemodynamically stressed vascular tissue: the insoluble elastin of experimental arteriovenous fistulae

Arteriovenous fistulae between the external jugular vein and the common carotid artery were surgically fashioned in eight sheep. The altered hemodynamics produced morphological changes similar to those observed in human atherosclerosis. The elastica is a major mural component and undergoes considerable structural variation during lesion development. The most significant biochemical changes in the elastin occur in the experimental vein region. These include a quantitative loss particularly in the midregion of the vein and a decrease in the concentration of up to 20% of the crosslinks (desmosine and isodesmosine). There is an increase in the cholesterol content of the elastin purified from both experimental artery and vein. The bound phospholipid was higher in the experimental artery and in the dilated experimental vein. There was a significant time-dependent loss of elastin in the stressed venous tissue.

Fetal pathology in human parvovirus B19 infection

In a current Netherlands study on the effects on mother and child of infection with the human parvovirus B19 during pregnancy, 10 pregnancies have been reported. Three of them ended before term: two in fetal death and one by elective abortion. In two of these fetuses B19 infection in cells other than those of the erythroid series was demonstrated, and in the one terminated, ocular malformation and extensive inflammatory reactions in all fetal and placental tissues were found. The presence of B19 DNA was demonstrated by dot hybridization in placental and fetal tissues. In the third no gross fetal abnormalities were found, although B19 DNA was detected in several fetal tissues by in-situ hybridization. Of the remaining seven pregnancies, six ended at term in the birth of apparently healthy babies. The other child was born near term with a low birthweight and multiple congenital malformations, but with no proof of intrauterine B19 infection. It is concluded that B19 infection in pregnancy can interfere with organ development and may lead to intrauterine fetal death.

Anti-DNA and antilymphocyte antibodies during acute infection with human parvovirus B19

Sera from patients in the acute and recovery stages of parvovirus B19 infection, and from individuals with no detectable antiparvovirus antibody were examined for the presence of anti-DNA and antilymphocyte antibodies. Sixty-eight percent of individuals recently recovered from parvovirus infection had elevated levels of antidouble stranded (ds) and antisingle stranded (ss) DNA antibodies. In addition, a cytotoxic IgM antilymphocyte antibody was detected in more than 88% of these same sera. Serial specimens from volunteers experimentally infected with parvovirus B19 were also tested for these autoantibodies and it was determined that the presence of antilymphocyte IgM was dependent on the stage of infection. The antilymphocyte IgM was occasionally detectable in sera containing rubella specific IgM (11%) or varicella zoster specific IgM (25%). However, in contrast to B19 infection, these antibodies were not cytotoxic. From the results of our study, we propose that parvovirus infection of hematologically normal individuals may be accompanied by a transient, subclinical autoimmune state.

Suppression of tumorigenicity in human cell hybrids derived from cell lines expressing different activated ras oncogenes

Four different human tissue-derived cell lines, each previously shown to express either a Ha-, Ki-, or N-ras-activated oncogene, were fused in four different paired combinations. The three combinations that involved the tumor line HT1080 (activated N-ras oncogene) were found to be tumorigenic in nude mice, but to different degrees. However, the fusion of the tumor lines EJ and SW480 (activated Ha-ras and Ki-ras, respectively) resulted in hybrid cells suppressed for tumorigenicity. The EJ x SW480 hybrids were found to harbor and express both of the activated ras oncogenes. The results suggest that tumorigenic suppression can occur in the presence of two transforming oncogenes of the ras family and that tumorigenicity associated with ras oncogene activation involves additional mechanisms that may differ among tumor cells.

A prospective study of acute idiopathic neuropathy. II. Antecedent events

The incidence of antecedent events and serological evidence of preceding infection were studied in 100 patients with acute idiopathic neuropathy and age and sex matched control subjects in South-East England. Symptoms of respiratory infections occurred within one month before onset of neuropathic symptoms in 38% of patients and 12% of controls (p less than 0.001) and symptoms of gastrointestinal infections in 17% of patients and 3% of controls (p less than 0.005). Immunisations, insect bites and animal contact were equally common in the patient and control subjects. Eight per cent of patients had undergone an operation within the preceding 3 months. Six per cent of patients had co-existing "autoimmune" diseases. Serological evidence of recent infection was identified in 31% of patients. Campylobacter jejuni (14%) and cytomegalovirus (11%) were both significantly more frequently demonstrated in patients than controls. Serological evidence of recent infection with mycoplasma (1%), Epstein Barr virus (1-2%) and parvovirus B19 (4%) was also identified in the patients but not more frequently than in the controls. Possible explanations for the association of these agents with acute idiopathic neuropathy include possession of antigens shared with myelin and inhibition of suppressor mechanisms.

Human parvovirus infections

Discovered by chance in 1974, the human serum parvovirus B19 is at present the only recognized, autonomous, pathogenic human parvovirus. For some years following its discovery, B19 was not associated with any defined clinical syndrome; although a high titre viraemia was often noted in infected individuals they were largely asymptomatic. In 1980 the causal association between B19 infection and aplastic crisis in chronic haemolytic anaemia began to emerge with the discovery of B19 as the agent responsible for aplastic crisis in sickle cell anaemia. This fulfilled the expectation of a disease of tissue comprising a large proportion of dividing cells, namely the erythropoietic elements of the bone marrow, anticipated in autonomous parvovirus infection where viral replication is confined to dividing cells. More recently, erythema infectiosum, an illness sharing many of the clinical features of rubella, has been found to be the common result of B19 infection, although a spectrum of disease is now emerging. Much effort is currently directed toward the elucidation of the effects of maternal B19 infection on the developing fetus.

Molecular differentiation of neurons from ependyma-derived cells in tissue cultures of regenerating teleost spinal cord

Cells cultured from the caudalmost area of regenerating teleost spinal cord differ both morphologically and in terms of molecular architecture from those of more rostral (more fully differentiated) areas of the cord. The caudalmost regenerating cord consists of an ependymal tube. Cells from this region have flattened or partially flattened cell somas and short spike projections in vitro; they do not exhibit the rounded cell somas nor the long, thin, branching neurites typical of differentiated neurons. A series of cultures taken from different areas along the length of regenerating spinal cord were examined for molecular differentiation by staining with a monoclonal antibody against non-phosphorylated neurofilament protein (SMI 32). None of the cells from the caudalmost culture of the regenerating spinal cord stained with antibody SMI 32. In cultures of more rostral regenerated cord, the cells with neuronal morphology do stain positively with the anti-neurofilament antibody. This result suggests that the cells in the cultures of caudalmost cord represent relatively undifferentiated ependymal cells, or ependyma-derived cells, which later differentiate into neurons and glia in the regenerating spinal cord.

Parvovirus associated aplastic crisis in homozygous sickle cell disease

Aplastic crises in homozygous sickle cell disease in Jamaica predominantly affect children and occur in epidemics. Of 67 cases in a cohort study of 314 children with homozygous sickle cell disease, 62 were attributable to human parvovirus infection. Affected children were aged 0.5-12.5 years, and the incidence rose to 28% by 10 years. No recurrences were seen. Symptoms and signs on presentation were attributable to the viraemia and acute anaemia. Asymptomatic thrombocytopenia was common. Blood transfusion was given in 54 cases (87%). Thirty eight children (61%) were admitted to hospital, 16 of whom were extremely ill on presentation and one of whom died soon after admission. Twenty four (39%) were managed as outpatients, 16 of whom were transfused. Parvovirus associated aplastic crisis is a self limited condition with excellent prognosis if diagnosed promptly and managed appropriately.

Transient pancytopenia associated with parvovirus infection in paroxysmal nocturnal haemoglobinuria

A 25 year old woman with a 15-year history of paroxysmal nocturnal haemoglobinuria developed transient pancytopenia following infection with human parvovirus B19. This is the first report of transient pancytopenia in a patient with an acquired haemolytic anaemia due to parvovirus. The possible mechanism of pancytopenia in such a case is discussed.

Variation of erythroid and myeloid precursors in the marrow and peripheral blood of volunteer subjects infected with human parvovirus (B19)

Infection of normal individuals with human parvovirus (B19) results in a mild disease (erythema infectiosum) but gives rise to aplastic crises in patients with chronic hemolytic anemias. The effects of this disease on hemopoiesis were investigated following intranasal inoculation of the virus into three volunteers. A typical disease ensued with a viremia peaking at 9 d. Marrow morphology 6 d after inoculation appeared normal but at 10 d there was a severe loss of erythroid precursors followed by a 1-2-g drop in hemoglobin, and an increase in serum immunoreactive erythropoietin. Erythroid burst-forming units (BFU-E) from the peripheral blood were considerably reduced, starting at the time of viremia and persisting for 4-8 d depending on the individual. Granulocyte-macrophage colony-forming units (CFU-GM) were also affected but the loss started 2 d later. Both CFU-GM and BFU-E showed a sharp overshoot at recovery. In the marrow, BFU-E and CFU-E were reduced at 6 and 10 d in the individual having the longest period of peripheral progenitor loss. In contrast, there was an increase in BFU-E and CFU-E in the subject with least change in peripheral progenitors. In the third subject, with an intermediate picture, there was a loss at 6 d but an increase at 10 d of erythroid progenitors. It is suggested that the architecture of the marrow might partially isolate progenitors from high titers of virus in the serum and individual variation in this respect might give the results observed.

Parvovirus infection in hospital practice

Eleven cases of human parvovirus (HPV) infection were diagnosed on the basis of positive IgM serology over a 9-month period in two London hospitals. These cases accounted for almost 30% of viral illness in which HPV serology had been requested. Ten of the cases presented with joint symptoms and/or rash and one case presented with evidence of a severe autoimmune haemolytic anaemia. Six patients had lymphadenopathy. Clinical and laboratory features of the cases are presented. HPV DNA was sought but not found in synovial fluid from one patient.

Explant cultures of teleost spinal cord: source of neurite outgrowth

The source of neurite outgrowth in explant cultures of normal adult Apteronotus spinal cord was examined. Explants which contained the central region of spinal cord, including ependyma, showed neurite outgrowth in culture. Explants which did not contain ependyma showed no neurite outgrowth. It is concluded that the ependymal region is necessary for neurite outgrowth in these cultures of adult teleost spinal cord. In addition, our failure to observe axon outgrowth clearly attributable to fluorescently back-labeled electromotor neurons in these cultures suggests that the exuberant neurite outgrowth in vitro is most probably due to cells other than the electromotor neurons. This explant culture system provides a unique opportunity to study neuronal differentiation, regeneration, and neurogenesis in vitro.

Some effects of water quality on the performance of high yielding cows in an arid climate

The water from wells in Saudi Arabia is often high in mineral content. The cows in this study had been receiving water containing between 4000 and 5000 ppm total dissolved solids. Four groups of 16 cows were calved down and milked under similar conditions in the hot summer months. Two of the groups were given normal well water and the other two groups received water after desalination in a reverse osmosis plant. One group on each type of water also had their water cooled. The groups of cows receiving treated water drank more water, consumed more concentrate and produced significantly more milk than the groups given normal well water. A similar effect on feed intake and milk production was seen when treated water was given to a 1000-cow unit with a similar number of control cows.

Parvovirus infection associated with aplastic crisis in a patient with HEMPAS

An aplastic crisis associated with parvovirus infection occurred in a patient suffering from hereditary erythrocytic multinuclearity associated with a positive acidified (Hams) test (HEMPAS). This case emphasises that any patient who has a shortened red cell survival is susceptible to an aplastic crisis induced by parvovirus.

Self-organization of ependyma in regenerating teleost spinal cord: evidence from serial section reconstructions

Multiple ependymal structures have been observed in regenerating spinal cord of the teleost Apteronotus albifrons. Evidence is presented for two modes of formation of the secondary ependymas: budding off from the primary ependyma, and de novo origin of a tube-like ependymal structure within a group of undifferentiated cells. Serial sections of regenerated cord provide evidence that undifferentiated cells not in immediate contact with the main ependymal layer can organize and differentiate into an ependymal structure in the regenerating spinal cord. These findings suggest that a significant amount of morphological organization can take place independent of the normal developmental sequence and environment.

Isolation of cDNA clones coding for the alpha-subunit of human beta-hexosaminidase. Extensive homology between the alpha- and beta-subunits and studies on Tay-Sachs disease

The lysosomal beta-hexosaminidases (N-acetyl-beta-glucosaminidase, EC 3.2.1.30) occur as two major isozymes, hexosaminidase A (alpha beta a beta b) and hexosaminidase B (2(beta a beta b)). To facilitate the investigations of the biosynthesis and structure of the enzymes and the nature of mutation in Tay-Sachs disease, we have isolated cDNA clones coding for the alpha-subunit. The polypeptide chains of hexosaminidase A (30 mg) were digested with trypsin, and peptides were isolated by reverse phase high pressure liquid chromatography and their amino acid sequences determined. One of alpha-chain peptides contained a string of seven amino acids from which two sets of oligonucleotides were specified. They were used to screen the SV40-transformed human fibroblast cDNA library of Okayama and Berg. Three cDNA clones, designated pHexA, identified from among 5 X 10(5) clones screened, contained the deduced amino-acid sequences of five alpha-chain peptides. Genomic DNA homologous to pHexA cDNA mapped to human chromosome 15 in somatic cell hybrids, as expected for the pre-alpha-polypeptide. Two of the clones contained identical polyadenylation sites, while the third was polyadenylated about 450 base pairs downstream. The two types of clones were found to correspond to a major 2.0-kilobase pair and a minor 2.3-kilobase pair mRNA species. Blot hybridizations of mRNA and DNA from Tay-Sachs variant fibroblasts revealed absence or reduction of levels of both mRNA species among infantile and juvenile variants, but no observable DNA alterations. Alignment of the pre-alpha- and pre-beta-polypeptides revealed 55% nucleotide and 57% amino acid homology. These data suggest a common origin of the HEXA and HEXB genes and account for the similar substrate specificities of the alpha-dimer subunit, hexosaminidase S, and hexosaminidase B.

Human serum parvovirus associated vasculitis

A 48 year old man had a severe symmetrical arthritis of knee and ankle joints accompanied by an extensive purpuric rash of both legs and several areas of skin necrosis. No other system was clinically involved. Human serum parvovirus-specific IgM was present in a blood sample taken 2 weeks after the onset of the clinical illness indicating recent infection with this virus. The patient was treated with complete bed rest, and the application of saline soaks to both legs. He had a recurrence of the rash 5 weeks after onset, but otherwise made a complete recovery. Purpura with skin necrosis has not previously been reported in association with this virus.

Rubella epidemiology in South East England

Analyses of data collected in a large survey (sample size greater than 3000) of rubella antibody in South East England, finely stratified according to age, reveal age-dependent changes in the pattern of virus transmission. The rate or force of infection changes from low in the young children to high in the 5- to 15-year-olds and back to low again in the adult age classes (there is a 50% reduction between the 5- to 15-year-olds and the 20+-year-olds). Raised levels of immunity are recorded in the teenage and young adult female segments of the population as a consequence of the UK rubella immunization programme. Mean antibody concentrations show a decline with age and are, on average, lower in vaccinated females when compared with unvaccinated males of the same age. The interpretation of horizontal cross-sectional serological data and future research needs are discussed.

Nerve-induced remodeling of muscle basal lamina during synaptogenesis

To identify mechanisms that regulate the deposition of the junctional basal lamina during synaptogenesis, immunocytochemical experiments were carried out on cultured nerve and muscle cells derived from Xenopus laevis embryos. In some experiments successive observations were made on individual muscle cells after pulse-labeling with a fluorescent monoclonal antibody specific for a basal lamina proteoglycan. In others, old and new proteoglycan molecules were differentially labeled with antibody conjugated to contrasting fluorochromes. These observations revealed that surface deposits of antibody-labeled proteoglycan remain morphologically stable for several days on developing muscle cells. Over the same period, however, new sites of proteoglycan accumulation formed that contained primarily those antigenic sites recently exposed at the cell surface. When muscle cells became innervated by cholinergic neurites, new proteoglycan accumulations were induced at the developing neuromuscular junctions, and these too were composed almost exclusively of recently deposited antigen. In older muscle cultures, where many cells possessed relatively high background concentrations of antigen over their surfaces, developing neuromuscular junctions initially showed a markedly reduced proteoglycan site-density compared with the adjacent, extrajunctional muscle surface. Much of this perineural region eventually became filled with dense, nerve induced proteoglycan plaques at later stages of synapse development. Motoneurons thus appear to have two, superficially paradoxical effects on muscle basal lamina organization. They first cause the removal of any existing, extrajunctional proteoglycan from the path of cell contact, and then induce the deposition of dense plaques of recently synthesized proteoglycan within the developing junctional basal lamina. This observation suggests that the proteolytic enzyme systems that have already been implicated in tissue remodeling may also contribute to the inductive interaction between nerve and muscle cells during synaptogenesis.