Genetic alterations in primary and secondary hyperparathyroidism

Hyperparathyroidism refers to a term representing a wide spectrum of parathyroid disorders that are characterized by the increased production of parathyroid hormone. Hyperparathyroidism was once thought to be tare but is now more commonly recognized, aifecting 1 in 500 women over 40 years of age. Yet the interpretation of parathyroid pathology is still controversial and confusing. Over the past 10 years, genetic changes ( ret and menin genes) involved in the pathogenesis of MEN 2 and MEN 1 have been discovered in succession. Different mutations of the calcium-sensing receptor gene have been identified in neonatal severe hyperparathyroidism and familial hypocalciuric hypercal-cemia, respectively. The HRPT 2 gene responsible for the development of heredltaty hyperparathyroidism and jaw tumors has been localized on the 1q21–31 locus. Several genetic alterations have also been characterized in primary and secondary hyperparathyroidism. Different genetic alterations appear to involve the development of different types of hyperparathyroidism. These novel advances give us new insights into the pathogenesis of hyperparathyroidism and allow better differentiation between the different types of parathyroid disorders.     

Altered EphA5 mRNA expression in rat brain with a single methamphetamine treatment

Methamphetamine is a potent and indirect dopaminergic agonist which can cause chronic brain dysfunctions including drug abuse, drug dependence and drug-induced psychosis. Methamphetamine is known to trigger molecular mechanisms involved in associative learning and memory, and thereby alter patterns of synaptic connectivity. The persistent risk of relapse in methamphetamine abuse, dependence and psychosis may be caused by such alterations in synaptic connectivity. EphA5 receptors constitute large families of tyrosine kinase receptor and are expressed almost exclusively in the nervous system, especially in the limbic structures. Recent studies suggest EphA5 to be important in the topographic projection, development, and plasticity of limbic structures, and to be involved in dopaminergic neurotransmission. We used in situ hybridization to examine whether methamphetamine alters EphA5 mRNA expression in the brains of adult male Wister rats. EphA5 mRNA was widely distributed in the medial frontal cortex, cingulate cortex, piriform cortex, hippocampus, habenular nucleus and amygdala. Compared to baseline expression at 0 h, EphA5 mRNA was significantly decreased (by 20%) in the medial frontal cortex at 24 h, significantly increased (by 30%) in the amygdala at 9 and 24 h, significantly but transiently decreased (by 30%) in the habenular nucleus at 1 h after a single injection of methamphetamine. Methamphetamine did not change EphA5 mRNA expression in the cingulate cortex, piriform cortex or hippocampus. Our results that methamphetamine altered EphA5 mRNA expression in rat brain suggest methamphetamine could affect patterns of synaptic connectivity, which might be responsible for methamphetamine-induced chronic brain dysfunctions.     

Cell lines that support replication of a novel herpes simplex virus 1 UL31 deletion mutant can properly target UL34 protein to the nuclear rim in the absence of UL31

Previous results indicated that the herpes simplex virus 1 (HSV-1) U(L)31 gene is necessary and sufficient for localization of the U(L)34 protein exclusively to the nuclear membrane of infected Hep2 cells. In the current studies, a bacterial artificial chromosome containing the entire HSV-1 strain F genome was used to construct a recombinant viral genome in which a gene encoding kanamycin resistance was inserted in place of 262 codons of the 306 codon U(L)31 open reading frame. The deletion virus produced virus titers approximately 10- to 50-fold lower in rabbit skin cells, more than 2000-fold lower in Vero cells, and more than 1500-fold lower in CV1 cells, compared to a virus bearing a restored U(L)31 gene. The replication of the U(L)31 deletion virus was restored on U(L)31-complementing cell lines derived either from rabbit skin cells or CV1 cells. Confocal microscopy indicated that the majority of U(L)34 protein localized aberrantly in the cytoplasm and nucleoplasm of Vero cells and CV1 cells, whereas U(L)34 protein localized at the nuclear membrane in rabbit skin cells, and U(L)31 complementing CV1 cells infected with the U(L)31 deletion virus. We conclude that rabbit skin cells encode a function that allows proper localization of U(L)34 protein to the nuclear membrane. We speculate that this function partially complements that of U(L)31 and may explain why U(L)31 is less critical for replication in rabbit skin cells as opposed to Vero and CV1 cells.     

Apparent genotype–phenotype correlation in childhood,adolescent, and adult Chediak‐Higashi syndrome

Chediak‐Higashi syndrome (CHS) is a rare autosomal recessive disorder characterized by severe immunologic defects, reduced pigmentation, bleeding tendency, and progressive neurological dysfunction. Most patients present in early childhood and die unless treated by bone marrow transplantation. About 10–15% of patients exhibit a much milder clinical phenotype and survive to adulthood, but develop progressive and often fatal neurological dysfunction. Very rare patients exhibit an intermediate adolescent CHS phenotype, presenting with severe infections in early childhood, but a milder course by adolescence, with no accelerated phase. Here, we describe the organization and genomic DNA sequence of the CHS1 gene and mutation analysis of 21 unrelated patients with the childhood, adolescent, and adult forms of CHS. In patients with severe childhood CHS, we found only functionally null mutant CHS1 alleles, whereas in patients with the adolescent and adult forms of CHS we also found missense mutant alleles that likely encode CHS1 polypeptides with partial function. Together, these results suggest an allelic genotype–phenotype relationship among the various clinical forms of CHS. © 2002 Wiley‐Liss, Inc.     

Combination-sensitive neurons in the medial geniculate body of the mustached bat: encoding of target range information.

1. Delay-tuned combination-sensitive neurons (FM-FM neurons) have been discovered in the dorsal and medial divisions of the medial geniculate body (MGB) of the mustached bat (Pteronotus parnellii). In this paper we present evidence for a thalamic origin for FM-FM neurons. Our examination of the response properties of FM-FM neurons indicates that the neural mechanism of delay-tuning depends on coincidence detection and involves an interaction between neural inhibition and excitation. 2. The biosonar pulse (P) and its echo (E) produced and heard by the mustached bat consist of four harmonics; each harmonic contains a constant frequency (CF) component and a frequency modulated (FM) component. Thus the pulse-echo pair contains eight CF components (PCF1-4, ECF1-4) and eight FM components (PFM1-4, EFM1-4). The stimuli used in this study consisted of CF, FM, and CF-FM sounds: paired CF-FM sounds were used to simulate any two harmonics of pulse-echo pairs. The responses of FM-FM neurons in the MGB were recorded extracellularly. We found that FM-FM neurons respond poorly or not at all to single sounds, respond strongly to paired sounds, and are tuned to the frequency and amplitude of each sound of the pair and to the time interval separating them (simulated echo delay). 3. All FM-FM neurons are facilitated by paired FM sounds and most are facilitated by paired CF sounds. Best facilitative frequencies measured with paired CF sounds fall outside the frequency ranges of the CF components of biosonar signals, whereas best facilitative frequencies measured with paired FM sounds fall within the frequency ranges of the FM components of biosonar signals. Thus FM-FM neurons are expected to respond selectively to combinations of FM components in biosonar signals. The FM components of pulse-echo pairs essential to facilitate FM-FM neurons are the FM component of the fundamental of the pulse (PFM1) in combination with the FM component of the second, third, or fourth harmonic of an echo (EFM2, EFM3, EFM4; collectively, EFMn). 4. The frequency combinations to which FM-FM neurons are tuned reflect small deviations from the harmonic relationship such as occurs in combinations of FM components from pulses and Doppler-shifted echoes. Compared with CF/CF neurons, however, FM-FM neurons are broadly tuned to stimulus frequency. Thus FM-FM neurons are Doppler-shift tolerant and relatively unspecialized for processing velocity information in the frequency domain.(ABSTRACT TRUNCATED AT 400 WORDS)     

An enzyme immunoassay for K-76 monocarboxylic acid, a novel anticomplementary compound

A competitive enzyme immunoassay for K-76 monocarboxylic acid (K-76COOH), a novel anticomplementary compound, was developed. K-76COOH was directly coupled with bovine serum albumin through a formation of Schiff base and successive reduction. The spectral data of the conjugate showed no evidence of a Schiff base form. Using the specific antiserum, the proposed homologous assay made it possible to detect K-76COOH at the lowest value of 1 ng/ml of plasma. The immunoassay was validated by the correlation with HPLC analyses. The time courses of plasma levels of K-76COOH after a single oral administration to beagle dogs were precisely determined with a very low absorption efficiency. From these results, it is suggested that the plasma values obtained are insufficient for K-76COOH to exert its anticomplementary action in vivo; thus K-76COOH may have another immunopharmacological function.     

Evaluation of the staining findings of immunofluorescence in unfixed or fixed renal biopsy specimens from patients with IgA nephropathy and membranous nephropathy

A study on the evaluation of staining findings of immunofluorescence in unfixed or fixed renal biopsy specimens is described. Renal biopsy specimens obtained from ten patients with IgA nephropathy and membranous nephropathy were embedded in gelatin or paraffin matrix. Renal biopsy specimens embedded in paraffin matrix were digested with 0.05% protease. The specimens were stained with FITC-conjugated anti-human IgA, IgG, IgM or C3 antisera at 4 degrees C overnight. IgA, IgG or IgM were markedly observed in glomeruli using unfixed materials embedded in gelatin matrix or 10% neutral buffered formalin fixed materials embedded in paraffin matrix from patients with IgA nephropathy and membranous nephropathy. There was no significant difference in the intensity or distribution of IgA, IgG or IgM deposition among the two different conditions of immunofluorescence in patients with such diseases. Although the deposition of IgA using unfixed materials embedded in gelatin matrix was prominently coarse granular or lumpy in glomeruli from patients with IgA nephropathy, that of IgA using 10% formalin fixed materials embedded in paraffin matrix was fine granular and/or interrupted linear in glomeruli. It was suggested that the immunofluorescence in renal biopsy specimens embedded in paraffin matrix after digestion with protease is useful for the evaluation of immunoglobulins in glomeruli from patients with IgA nephropathy or membranous nephropathy.     

Spectral imaging fluorescence microscopy

The spectral resolution of fluorescence microscope images in living cells is achieved by using a confocal laser scanning microscope equipped with grating optics. This capability of temporal and spectral resolution is especially useful for detecting spectral changes of a fluorescent dye; for example, those associated with fluorescence resonance energy transfer (FRET). Using the spectral imaging fluorescence microscope system, it is also possible to resolve emitted signals from fluorescent dyes that have spectra largely overlapping with each other, such as fluorescein isothiocyanate (FITC) and green fluorescent protein (GFP).     

Corticofugal amplification of facilitative auditory responses of subcortical combination-sensitive neurons in the mustached bat

Recent studies on the bat's auditory system indicate that the corticofugal system mediates a highly focused positive feedback to physiologically "matched" subcortical neurons, and widespread lateral inhibition to physiologically "unmatched" subcortical neurons, to adjust and improve information processing. These findings have solved the controversy in physiological data, accumulated since 1962, of corticofugal effects on subcortical auditory neurons: inhibitory, excitatory, or both (an inhibitory effect is much more frequent than an excitatory effect). In the mustached bat, Pteronotus parnellii parnellii, the inferior colliculus, medial geniculate body, and auditory cortex each have "FM-FM" neurons, which are "combination-sensitive" and are tuned to specific time delays (echo delays) of echo FM components from the FM components of an emitted biosonar pulse. FM-FM neurons are more complex in response properties than cortical neurons which primarily respond to single tones. In the present study, we found that inactivation of the entire FM-FM area in the cortex, including neurons both physiologically matched and unmatched with subcortical FM-FM neurons, on the average reduced the facilitative responses to paired FM sounds by 82% for thalamic FM-FM neurons and by 66% for collicular FM-FM neurons. The corticofugal influence on the facilitative responses of subcortical combination-sensitive neurons is much larger than that on the excitatory responses of subcortical neurons primarily responding to single tones. Therefore we propose the hypothesis that, in general, the processing of complex sounds by combination-sensitive neurons more heavily depends on the corticofugal system than that by single-tone sensitive neurons.     

Antigenic variation of the Epstein–Barr virus nuclear antigen EBNA1 as revealed by monoclonal antibodies

The Epstein–Barr virus (EBV) nuclear antigen EBNA1 plays an essential role in the replication of EBV episomes in latently infected cells and is the only viral protein that is consistently expressed in all programs of latent EBV gene expression. In this study, four monoclonal antibodies (MoAbs) directed to a region (amino acid residues 442–530) of EBNA1 were generated. Competitive enzyme-linked immunosorbent assay (ELISA) experiments using biotinylated MoAbs showed that they recognized distinct epitopes. Reactivity of these MoAbs with various laboratory EBV strains and field EBV isolates was shown to be heterogeneous in that EBNA1 from certain strains (isolates) was recognized and that from others was not. All four MoAbs showed such heterogeneous reactivity, and moreover, each MoAb showed a distinct spectrum of reactivity with these EBV strains (isolates). These results demonstrate an extensive structural variation in this region of EBNA1 as predicted by previous sequencing studies. These MoAbs will be useful as probes to dissect this structural heterogeneity of EBNA1.