No evidence for prion protein gene locus multiplication in Creutzfeldt-Jakob disease

Precedent of causative multiplication of key gene loci exists in familial forms of both Alzheimer's and Parkinson's diseases. Genetic Creutzfeldt-Jakob disease (CJD) is often clinically indistinguishable from sporadic disease and inexplicably, a negative family history of a similar disorder occurs in around 50–90% of patients harboring the most common, disease-associated, prion protein gene (PRNP) mutations. We undertook semi-quantitative analysis of the PRNP copy number in 112 CJD patients using quantitative polymerase chain reaction. All included cases satisfied classification criteria for probable or definite sporadic CJD, ascertained as part of longstanding, prospective, national surveillance activities. No examples of additional copies of the PRNP locus as an explanation for their disease was found in any of the 112 sporadic CJD patients. Hence, contrasting with more common, age-related neurodegenerative diseases, the genetic aetiology in human prion disease continues to appear entirely restricted to small scale mutations within a single gene, with no evidence of multiplication of this validated candidate gene locus as a cause.     

No evidence for preferential involvement of medial temporal lobe structures in high-functioning autism

BACKGROUND: Autism is a neurodevelopmental disorder associated with slight increases in brain volume. There has been some suggestion that medial temporal lobe structures may be preferentially involved in this disorder, although results have not always been consistent. Here, we investigate amygdala and hippocampus volumes in medication-naive subjects with high-functioning autism. METHOD: Whole-brain magnetic resonance imaging scans were acquired from 42 patients and 42 closely matched, healthy control subjects. RESULTS: Amygdala volume did not differ significantly between patients and controls. A significant increase in hippocampal volume was proportional to an increase in overall brain volume. CONCLUSIONS: These results argue against preferential involvement of medial temporal lobe structures in autism, at least in high-functioning medication-naive individuals.     

Growth ofBabesia bigemina parasites in suspension cultures for vaccine production

An AustralianBabesia bigemina vaccine strain was maintained in suspension culture for 40 days. Parasite growth was compared using two tissue-culture flask sizes (25 and 75 cm²), four gas mixes (2%, 2.5%, 3% and 3.5% O₂; 5% CO₂; and the balance N₂) and four packed blood cell (PCV) volumes (7%, 9%, 13% and 18%). The best continuous parasite yields were obtained from suspension cultures in 75-cm² flasks at a PCV of 13% and gas mixtures of 2%–3% O₂, 5% CO₂ and the balance N₂. Parasite yields per millilitre of culture medium were 3 times those obtained in microaerophilous stationary-phase cultures. The method has thus far been used for 6 months to produce the Australian requirements for hveB. bigemina vaccine.     

Evidence for preferential multiplication of the internal unit in tandem repeats of the mating factor a genes in Saccharomyces yeasts

Summary We have determined DNA sequences of the mating factor a genes of Saccharomyces uvarum and Saccharomyces italicus and compared them to that of the MF1 gene of S. cerevisiae. The DNA sequences of the mating factor genes in both species were almost completely identical to that of the MF1 gene of S. cerevisiae except for the number of tandem repeated units; these latter consisted of a spacer peptide and a mature mating factor and there were three units in S. uvarum and five units in S. italicus compared with four units in the MF1 of S. cerevisiae. From the detailed comparison of DNA sequences of the spacer peptide-mating factor units from these three species, the high sequence homology can be recognized in the internal units of the tandem repeats. This suggests that the internal units might be multiplied preferentially in the tandem repeated units of mating factor genes.     

The multiplication of influenza virus in enucleated BHK cells fused with chicken erythrocytes.

Chicken erythrocyte nuclei that were introduced by cell fusion into enucleated BHK cells supported the production of influenza virus nucleoprotein but not haemagglutinin or neuraminidase antigens.     

Human lymphocyte affinity for sheep erythrocytes in young and aged healthy subjects.

The kinetics of sheep erythrocyte rosette formation by human peripheral blood lymphocytes from young-adult and aged individuals were studied in 20 paired experiments. No difference in the rate and saturation plateau of formation could be found despite a slight increase in early rosette-forming cells. We conclude that the membrane affinity for sheep erythrocytes is unaffected by ageing and that the proportion of the circulating early E-RFC subpopulation is increased in healthy older subjects.     

Myotonic dystrophy--no evidence for preferential transmission of the mutated allele: a prenatal analysis

Myotonic dystrophy is the commonest autosomal dominant type of muscular dystrophy in adults. It is one of the trinucleotide repeat expansion disorders, and its severity correlates with the number of CTG repeats in the myotonic dystrophy gene. It has been suggested that myotonic dystrophy exhibits the phenomenon of preferential transmission of the larger mutated alleles that has been described in other trinucleotide repeat disorders. Several authors have reported that the frequency of transmission of the mutated alleles is higher than 50%--a finding that, if true, does not comply with the Mendelian laws of segregation. However, these studies were based on data from the analysis of pedigrees with ascertainment bias. In our study, we determined the frequency of transmission of mutated alleles using data from prenatal molecular studies, which are not subject to ascertainment bias. This is the first study to examine the segregation of the mutated alleles in myotonic dystrophy in pregnancy. Eighty-three fetuses were examined, 30 of 62 mothers (48.38%) and 8 of 21 fathers (38.09%) transmitted the mutated allele, giving an overall transmission rate of 45.78%. We found no evidence of statistically significant deviation of the frequency of transmission of the mutated alleles from the 50% expected in autosomal dominant disorders. This study, unlike previous ones, excludes preferential transmission in myotonic dystrophy, a finding that may be attributable to the lack of correction for ascertainment bias in previous studies and to the use of prenatal data in this study.     

Differential blood clearance rates of xenogenic erythrocytes in young rabbits

Guinea-pig erythrocytes are cleared very rapidly from the circulating blood of 10-day-old rabbits; in contrast, sheep and mouse erythrocytes are cleared twelve to thirteen times more slowly, while rat erythrocytes are cleared six times more slowly. The differential rates of blood clearance of these xenogeneic erythrocytes largely substantiate differences between low titres of haemagglutinins or haemolysins, either naturally acquired or of maternal origin. Interference by such antibody in induction of the plaque-forming cell response and the minimum time antigen must persist in the circulation for successful induction of a haemolytic antibody-forming cell response are discussed.     

Direct and indirect evidence for the reversibility of cirrhosis

The aim of this study was to assess the reversibility of cirrhosis after therapy in a large series of patients with cirrhosis from various etiologies. We performed a retrospective study of 113 patients with biopsy-proven cirrhosis who underwent specific therapy and follow-up biopsies. Two pathologists performed blinded analyses of indirect biochemical and morphological signs of cirrhosis. Fourteen (12.4%) of the 113 cirrhotic patients had biopsy-proven disappearance of cirrhosis, defined as a decrease of 2 or greater in their METAVIR fibrosis score: 8 were related to hepatitis C virus, 3 to hepatitis B virus, and 3 to autoimmune cirrhosis. Necro-inflammatory activity decreased from 2.4 +/- 0.65 to 0.85 +/- 0.9 (P = .004), and fibrosis from 4 to 1.7 +/- 0.61 (P = .001). Prothrombin time (n = 1), platelet count (n = 2), serum albumin level (n = 2), and ultrasound abnormalities (n = 6) normalized in patients who had initial abnormalities. Hyaluronic acid and procollagen type III serum level decreased in all. In the 11 patients with regression of viral cirrhosis, 2 were nonresponders and 9 were responders, including 2 relapsers. The 3 patients with regressive autoimmune cirrhosis were complete responders to immunosupressive therapy. Using repeated liver biopsies, clinicobiochemical, radiologic, and endoscopic tests, we provide evidence for potential reversibility of cirrhosis after long-lasting suppression of the necro-inflammatory activity of liver disease.     

Direct evidence for presynaptic inhibitory mechanisms in crayfish sensory afferents.

1. The central control of sensory inputs from a proprioceptor [chordotonal organ (CO)] in the second joint [coxo-basipodite (CB)] of the fifth leg was studied in crayfish in vitro preparations (Fig. 1A). Simultaneous intracellular recordings from CBCO terminals (CBT) and postsynaptic motoneurons (MNs) were performed along with micropipette pressure ejection or bath application of gamma-aminobutyric acid (GABA), to study the presynaptic mechanisms at work in the CBT (Fig. 1B). 2. Two intracellular recordings were used to show that the spikes never overshoot, and that the more central the recording site within the neuropile, the smaller the spikes (Fig. 2). Only electrotonic conduction occurs, therefore, in the sensory afferents within the ganglion. 3. Pressure ejection of GABA close to the recording site of CBTs in the ganglion (Fig. 3A) gave rise to a membrane depolarization, the reversal potential of which was about -25 mV (Fig. 7), as well as to an increase in the membrane conductance (Fig. 3C) and a decrease in the orthodromic spike amplitude; moreover, it did not elicit either hyperpolarization, or any change in the membrane conductance of the postsynaptic MN (Fig. 3B), which indicates that pressure ejection of GABA affected only a restricted area around the CBT and not the postsynaptic MNs. 4. In CBT, spontaneous primary afferent depolarizations (PADs) occurred irregularly when the activity of the preparation was not rhythmic (Fig. 4A), and in bursts when the preparation displayed fictive locomotion (Fig. 4B). In the latter case, antidromic spikes were sometimes superimposed on PADs (Fig. 4D). The amplitude of the PADs was reduced when picrotoxin (PTX), a GABA antagonist, was applied (Fig. 5), which suggests that GABA may be involved in spontaneous PADs. The reversal potential of PADs was about -25 mV (Figs. 6 and 7). 5. During simultaneous recordings from a CBT and a monosynaptically related MN, GABA applied by pressure ejection close to the CBT (Fig. 8A) completely suppressed the excitatory postsynaptic potentials (EPSPs) elicited by CBT spikes in the MN (Fig. 8, B and D). This was due to a presynaptic mechanism because no change in the membrane potential or membrane conductance was observed in the MN (Fig. 8C) and most of the CBTs associated with a given MN were affected (Fig. 9). 6. Simultaneously recording from a CBT and a monosynaptically related MN demonstrated that, during bouts of PADs, the spike amplitude decreased in proportion to the PAD amplitude (Fig. 10A).(ABSTRACT TRUNCATED AT 400 WORDS)     

Testicular persistence of Parvovirus B19: evidence for preferential infection of germ cell tumors

Human Parvovirus B19 has previously been implicated in the pathogenesis of testicular germ cell tumors, but this could not have been confirmed. This study was designed to investigate the testicular persistence of Parvovirus B19 and possible associations with germ cell tumors. Paraffin-embedded or fresh tissues from 36 germ cell tumors, 20 germ cell aplasias, 26 normal testicular tissues, 20 liver tissues, and 20 spleen tissues were evaluated by two different molecular assays: a nested PCR for Parvovirus B19 capsid genes and a commercial quantitative real-time PCR. Positive results were further confirmed by another commercial real-time PCR assay. Viral DNA was detected in 3 of 36 (8.3%) germ cell tumors, but not in other groups. Viral loads observed in all positive samples were less than 20 IU/reaction, suggesting very low levels of viral replication or latency. These results either directly or indirectly imply the involvement of Parvovirus B19 with testicular germ cell tumors. Viral persistence in normal testis, germ cell aplasia tissues, or hepatic/splenic tissues was not observed in this study.     

Further evidence for preferential production of IgG2 anti-DNP antibody in guinea pigs immunized with DNP-Escherichia coli

As reported previously, radioimmunoelectrophoretic analysis of guinea pig antisera to 2,4-dinitrophenylated cells of Escherichia coli (DNP-E. coli) revealed that synthesis of antibodies to 2,4-dinitrophenyl residues (DNP) was restricted to one of the IgG antibodies, IgG2, when guinea pigs were immunized with the antigen in both the presence and absence of Freund's adjuvants. In order to confirm further this unique antibody response to DNP-E. coli, the subclass of anti-DNP antibodies produced was analyzed by DEAE-cellulose chromatography, electrofocusing and determination of antibody activities. The results so far obtained indicated that about 97% of the antibodies produced was of the IgG2 subclass and only a trace of the IgG1 antibody was produced, independently of the mode of immunization, though a small amount of IgG1 anti-DNP antibody was produced concomitantly on increasing the immunizing dose to 3.0 mg in saline. Furthermore, the cell-free extract prepared from DNP-E. coli also induced the preferential production of IgG2 anti-DNP antibody.     

Dw subtypes of DR4 in rheumatoid arthritis: evidence for a preferential association with Dw4

We have determined the frequency of the DR4-associated Dw subtypes, defined by homozygous typing cells, in a group of rheumatoid arthritis (RA) patients on second-line drug therapy. The frequency of DR4 in these patients was 86%. Among Caucasians, the frequency of Dw4 in the DR4-positive patients was significantly increased (68%) as compared to DR4-positive normal individuals (46%; p less than 0.025). Dw4, as compared to the other DR4 subtypes tested, may also be associated with more severe disease as judged by indices of functional impairment and joint damage. In a small subgroup of non-Caucasian (black and Native American) patients, the Dw13 (DB3) subtype of DR4 was often seen, suggesting that RA may have different Dw associations in different ethnic groups.     

Lipopolysaccharide-reactive B cells against bromelain-treated mouse erythrocytes: preferential migration to and survival in the peritoneal cavity

The ratio of lipopolysaccharide (LPS)-reactive B cells specific for bromelain-treated mouse erythrocytes (BrMRBC) to general LPS-reactive B cells is far higher in the peritoneal cavity of normal mice than in their spleen. To investigate the high concentration of anti-BrMRBC LPS-reactive B cells in the peritoneal cavity, spleen and peritoneal cells from (CBA/N X C3H/He)F1 female normal mice were injected intravenously and intraperitoneally into F1 male X-linked immunodeficient mice. Both groups of B cells in the intravenously transferred cell population were able equally to home in the spleen, but only anti-BrMRBC LPS-reactive B cells could be detected migrating into the peritoneal cavity. About half the anti-BrMRBC LPS-reactive B cells in the intraperitoneally transferred cell population could be recovered from the peritoneal cavity, but general LPS-reactive B cells were eliminated rather rapidly from the peritoneal cavity. Neither group of B cells could be detected migrating from the peritoneal cavity into the spleen. These findings suggest that the high concentration of anti-BrMRBC LPS-reactive B cells in the peritoneal cavity may be caused by their preferential ability to penetrate into the peritoneal cavity through circulation and survive there.     

Study of phagocytosis of senescent erythrocytes in young and elderly individuals

There is a decrease in the percentage contribution of a heavy density fraction of red blood cells to whole blood with increasing age. The aim of this study was to investigate in the young and elderly the interaction between monocytes and different erythrocyte suspensions: senescent red blood cells, erythrocytes stored with or without serum, and desialylated red blood cells. The results obtained with senescent red blood cells and erythrocytes stored with serum show the involvement of autologous IgG in the selective removal of erythrocytes. These values were higher in elderly individuals, indicating that this process increases with age. Our observation suggest that desialylation is not involved in the increased removal of erythrocytes observed in elderly individuals. Received: 3 October 2002 / Accepted: 11 December 2002 Correspondence to C. Biondi