Identification and characterization of a telomerase activity from Schizosaccharomyces pombe

A telomerase-like primer extension activity has been detected in chromatographic fractions derived from Schizosaccharomyces pombe extracts. This primer extension activity acts preferentially on dG-rich oligodeoxynucleotides, is sensitive to RNase A pretreatment and requires all four deoxynucleotides for optimal polymerization. The extension products are also truncated by the inclusion of any one of the four dideoxynucleotides, consistent with the presence of all four bases in the S.pombe telomeric repeats. The intensity distribution of the extension products and the dideoxynucleotide termination pattern suggest that nucleotide addition is template directed, and that telomere-like sequences are added to the primers. In particular, the sequence d(CGGTTA), a variant of the S.pombe telomeric repeat, can be added directly by the in vitro activity. Partially purified S.pombe telomerase sediments as a 35S particle, suggesting that it exists in vivo as part of a large multi-protein complex.

Optical resolution of DL-alanine by using immobilized Aspergillus oryzae cells

Mycelium pellets with diameters of 1-2 mm and containing abundant aminoacylase were obtained by the liquid fermentation of Aspergillus oryzae 3042. By the cross-linking method with reagents of gelatin and formaldehyde, the immobilized A. oryzae cells (IAC) were prepared with much higher activity and reactive properties. The effects of factors on enzymatic activity of IAC were investigated. When substrate concentration was less than 0.15 mol/L, the Michaelis-Menten mechanism was suitable for this reaction.

[Evaluating clinical significance of tumor necrosis factor-alpha and hydroxyproline in blood of patients with active pulmonary tuberculosis]

OBJECTIVE

To evaluate the clinical significance of tumor necrosis factor-alpha (TNF-alpha) and hydroxyproline (HYP) in blood of patients with active pulmonary tuberculosis (APT).

METHOD

Contents of TNF-alpha and HYP in blood of 28 patients with APT and 17 normal subjects were determined with enzyme-linked immunosorbent assay and ultraviolet spectrophotometer respectively.

RESULT

It was found that the concentrations of TNF-alpha and HYP in patients with APT before antituberculosis treatment were obviously higher than those of the normal subjects (192.85 +/- 37.14 ng/L vs 89.36 +/- 23.18 ng/L and 4.96 +/- 1.13 mg/L vs 1.64 +/- 0.33 mg/L respectively, all P < 0.001) and those who received 3- month anti-tuberculosis treatment (192.65 +/- 37.14 ng/L vs 112.50 +/- 44.93 ng/L and 4.96 +/- 1.13 mg/L vs 2.17 +/- 0.39 mg/L respectively, all P < 0.001). TNF-alpha level was significantly correlated with HYP (r = 0.5132, P < 0.001).

CONCLUSION

The results indicate that TNF-alpha might play an important role in inducing pulmonary tissue damage of APT, and the lowering of HYP content in blood might indicate that pulmonary tuberculosis is recovering from active stage.

Arrest of the cell cycle by the tumour-suppressor BRCA1 requires the CDK-inhibitor p21WAF1/CiP1

Much of the predisposition to hereditary breast and ovarian cancer has been attributed to inherited defects in the BRCA1 tumour-suppressor gene. The nuclear protein BRCA1 has the properties of a transcription factor, and can interact with the recombination and repair protein RAD51. Young women with germline alterations in BRCA1 develop breast cancer at rates 100-fold higher than the general population, and BRCA1-null mice die before day 8 of development. However, the mechanisms of BRCA1-mediated growth regulation and tumour suppression remain unknown. Here we show that BRCA1 transactivates expression of the cyclin-dependent kinase inhibitor p21WAF1/CIP1 in a p53-independent manner, and that BRCA1 inhibits cell-cycle progression into the S-phase following its transfection into human cancer cells. BRCA1 does not inhibit S-phase progression in p21-/- cells, unlike p21+/+ cells, and tumour-associated, transactivation-deficient mutants of BRCA1 are defective in both transactivation of p21 and cell-cycle inhibition. These data suggest that one mechanism by which BRCA1 contributes to cell-cycle arrest and growth suppression is through the induction of p21.

Immunohistochemical localization of lysosomal cathepsin D in schwannomas

The immunohistochemical localization of cathepsin D (CD) was demonstrated for the first time in 54 schwannomas (32 intra- and 22 extracranial; 47 benign and 7 malignant) and 5 normal nerve fibers. Granular or vesicular CD-reactive structures were observed in all normal Schwann cells. All tumors contained CD-reactive tumor cells, although the population of CD-reactive tumor cells, the density, intracellular localization, and morphology of CD-reactive structures, and the intensity of CD immunoreactivity varied from case to case, portion to portion, and cell to cell, differing variously from those in normal Schwann cells. The variations were greater in malignant than in benign schwannomas. In mildly degenerate tumor cells, CD immunoreactivity was increased, possibly in response to the increased intracellular degenerate proteins, suggesting that the mechanism of induction of lysosomal proteases preserved in normal cells is not affected by the process of neoplastic transformation. In lesions of severe degeneration or necrosis, CD immunoreactivity was lost in most tumor cells but was strong in macrophages invading the lesions and perivascular regions. CD immunoreactivity was observed at various intensities in tumor cells in the Antoni type A area but not in most tumor cells in the Antoni type B area, suggesting that Antoni type B lesions show degenerative changes. The presence of CD-reactive tumor cells in all tumors examined and strong CD immunoreactivity observed at the invasion front of tumors in some cases of benign or malignant schwannoma suggests the possible role of CD in tumor invasion in some cases.

Cyclopia in one of discordant twins: a case report

Cyclopia is an uncommon congenital anomaly resulting from arrest of the development of the anterior end of the neural plate. It is always associated with abnormalities of the brain. Cyclopia has never been reported in one twin only. In this report, we describe a case of cyclopia in a female infant with normal karyotype who was one of discordant twins. The infant died perinatally. The parents were healthy and not sanguineously related. Prenatal imaging studies revealed cyclopia, holoprosencephaly and hypognathia. Postmortem examinations revealed one orbit, one eyeball and absence of the nose. The central nervous system included rudimentary cerebral hemispheres with fusion of the two lateral ventricles and the third ventricle forming a single large cavity. The superior aspect of each cerebral hemisphere consisted of only a transparent membrane. The olfactory bulb nad tract was absent. The optic nerves were not identified.

[Analysis of chromosome karyotype of Lycium chinense Mill]

The chromosome karyotypes of wild Lycium chinese and its cultivated breeds for vegetable have been studied. The Chromosome 12 of both has a satellite. The former, with 24 chromosomes and 1B karyotype, is a diploid and its karyotype formula is 2n = 2x = 24 = 18m + 6sm. The chromosome number of the latter is 48. As a tetrploid, it has 2B karyotype and a karyotype formula 2n = 4x = 48 = 36m + 12sm.

Cloning, human chromosomal assignment, and adipose and hepatic expression of the CL-6/INSIG1 gene

Rat CL-6 is the most highly insulin-induced gene in a liver cell line and is expressed in proliferating liver during regeneration and development. CL-6 is now denoted INSIG1 (insulin-induced gene 1). Human INSIG1 was isolated and found to be 80% identical to the rat gene within the translated region. It was located on human chromosome 7 within band q36. The human INSIG1 promoter conferred a high level of expression in both liver and fibroblast cell lines. INSIG1 expression was upregulated at the transcriptional level in rat regenerating liver and induced in a model of murine adipocyte differentiation, suggesting that INSIG1 may play a role in growth and differentiation of tissues involved in metabolic control.

HRS/SRp40-mediated inclusion of the fibronectin EIIIB exon, a possible cause of increased EIIIB expression in proliferating liver

Serine-arginine (SR)-rich proteins are believed to be important in mediating alternative pre-mRNA splicing. HRS/SRp40 expression is elevated in liver cell proliferation during development, regeneration, and oncogenesis. We tested whether HRS expression correlates with the appearance of alternatively spliced fibronectin transcripts during liver growth. HRS was highly expressed during the proliferative phase of liver development, correlating with expression of the fibronectin EIIIB alternative exon. In regenerating liver, HRS protein was induced in a time course consistent with the observed increase in fibronectin transcripts containing the EIIIB exon, particularly in nonparenchymal liver cells. Furthermore, in an in vivo assay, HRS, and not other SR proteins, directly mediated EIIIB exon inclusion in the fibronectin transcript. This alternative splicing was dependent on a purine-rich region within the EIIIB exon to which HRS specifically bound. We have established that HRS has the potential to contribute to the regulation of fibronectin pre-mRNA splicing during liver growth. Changes in fibronectin forms may be important in modifying liver architecture during the proliferative response, thus providing a potential mechanism by which SR proteins may participate in cellular growth control.

Posttransplant lymphoproliferative disorders: a fine-needle aspiration biopsy study

Fine-needle aspiration biopsy (FNAB) has been used with high sensitivity and specificity in the diagnosis of both Hodgkin's and non-Hodgkin's lymphoma. However, studies of FNAB of posttransplant lymphoproliferative disorders (PTLDs) are rare. The clinical course of 593 allograft recipients (cardiac, 288; renal, 250; lung, 50; and heart/lung, 5) was reviewed. Twenty-six patients developed PTLD with an overall incidence of 4.4%. Of these patients, 12 underwent FNAB. Their age ranged from 33-67 yr (mean, 55 yr). The interval between transplantation and FNAB ranged between 2-14 mo (average, 8.4 mo). The lungs were the most common site aspirated (7 cases), followed by lymph nodes (3 cases) and other extranodal sites (2 cases, liver and paraspinal mass). The cytologic features of these aspirates could be classified into two categories: a polymorphous smear composed of a spectrum of mature and immature lymphocytes with scattered plasma cells and histiocytes; and a monotonous population of large lymphoid cells consistent with malignant lymphoma, large-cell type. Surgical biopsies were available in 10 (83.3%) cases and confirmed the FNAB diagnosis. In summary, FNAB appears to be a highly sensitive and specific diagnostic tool in patients with PTLD.

[Effects of the double chamber intra-aortic balloon pumping on the renal circulation]

The effects of the double chamber intra-aortic balloon (DIAB) and the single chamber intra-aortic balloon (SIAB) on the hemodynamic parameters in the kidney were studied. No negative effect of both cases was observed. Before and after removing the renal nerve system, the DIAB was used and the results had been compared. The pulse produced by pumping activized the renal nerve system and reduced the renal vascular resistance. Therefore the reduction of the renal vascular resistance is an important reason for increasing the renal blood flow during intra-aortic balloon pumping.

Localization of BRCA1 and a splice variant identifies the nuclear localization signal

Inherited mutations in BRCA1 confer susceptibility to breast and ovarian neoplasms. However, the function of BRCA1 and the role of BRCA1 in noninherited cancer remain unknown. Characterization of alternately spliced forms of BRCA1 may identify functional regions; thus, we constructed expression vectors of BRCA1 and a splice variant lacking exon 11, designated BRCA1 delta 672-4095. Immunofluorescence studies indicate nuclear localization of BRCA1 but cytoplasmic localization of BRCA1 delta 672-4095. Two putative nuclear localization signals (designated NLS1 and NLS2) were identified in exon 11; immunofluorescence studies indicate that only NLS1 is required for nuclear localization. RNA analysis indicates the expression of multiple, tissue-specific forms of BRCA1 RNAs; protein analysis with multiple antibodies suggests that at least three BRCA1 isoforms are expressed, including those lacking exon 11. The results suggest that BRCA1 is a nuclear protein and raise the possibility that splicing is one form of regulation of BRCA1 function by alteration of the subcellular localization of expressed proteins.

Early versus deferred zidovudine monotherapy: impact on AIDS-free time and survival in the multicenter AIDS cohort study

The objective of this study was to compare the time to AIDS and to death between men receiving zidovudine therapy before or not before the diagnosis of AIDS. For the time to AIDS comparison, 821 men receiving zidovudine therapy before the diagnosis of AIDS were pair matched with men who did not receive zidovudine therapy until after diagnosis on their CD4 cell count (+/- 75 cells/mm3), haemoglobin level (+/- 0.75 g/dl), number of clinical symptoms and study visit at the time of initiation of zidovudine therapy and were monitored for a median of 2.08 years. For the time to death comparison, 186 men who received zidovudine therapy prior to AIDS diagnosis were pair matched on the same variables to men who received zidovudine therapy only after the AIDS diagnosis, and were monitored for a median of 2.88 years. Only men with < 350 CD4 cells/mm3 who received zidovudine therapy prior to AIDS diagnosis remained AIDS free significantly longer than their pair match who did not (P < 0.0001). The median extension of time to AIDS was 0.61 years for men with < 200 CD4 cells/mm3 and 1.13 years for men with 200-349 CD4 cells/mm3. Cox regression analysis showed a significantly increased time to AIDS for the men with < 350 CD4 cells/mm3, both before and after adjustment for the use of prophylactic drugs against Pneumocystis carinii pneumonia. No difference was seen in the time to death between men receiving zidovudine therapy before or only after AIDS diagnosis. Zidovudine treatment of asymptomatic HIV-1-infected men provides significant benefit to men with < 350 CD4 cells/mm3 by extending AIDS-free time, but does not extend survival. The analytical technique used is applicable to other observational studies of treatment.

Detection of minimal residual disease in leukemia using polymerase chain reaction and restriction analysis

OBJECTIVE

To investigate the relationship between the clinical outcome of childhood acute lymphoblastic leukemia and the status of minimal residual disease after termination of therapy.

METHODS

A total of 18 children with acute lymphoblastic leukemia were studied. Eleven cases were treated with chemotherapy, the other 7 with autologous peripheral blood stem cell transplantation (ABSCT) or autologous bone marrow transplantation (ABMT). The outcome of the 18 patients was obtained by clinical follow-up. Minimal residual disease was detected by means of the polymerase chain reaction (PCR) and restriction analysis.

RESULTS

Minimal residual disease was detected in 9 patients after completion of therapy. Three out of the 9 patients relapsed within 3 to 6 months. Among the other 9 patients with no detectable minimal residual disease, no one relapsed.

CONCLUSIONS

PCR detection of minimal residual disease after termination of therapy can identify patients at risk for relapse in future. Minimal residual disease that cannot be detected after termination of therapy may be one of the important factors for long-term disease-free survival.

Mechanism of anti-beta-adrenoceptor antibody mediated myocardial damage in dilated cardiomyopathy

Antibodies against beta(1)-adrenoceptor can be detected in serum of patients with dilated cardiomyopathy (DCM), which have beta-agonist-like activity, and induce a positive chronotropic effect on cardiac myocytes by its persistence at full strength. Effects of the antibodies against beta-adrenoceptor from sera of patients with DCM on myocardial cytotoxicity and cytoplasmic free Ca(2+)-concentration ([Ca2+]i) were observed in the cultured single layer SD rat ventricular cells by using the cytotoxicity assay and fluorescent Ca(2+)-indicator fura-2/AM. The positive sera of the anti-beta-adrenoceptor antibodies from patients with DCM markedly enhanced myocardial [Ca2+]i. Betaloc, a beta(1)-receptor blocker, might inhibit the increase of the antibody-mediated myocardial [Ca2+]i, and the sera from healthy donors had no effect on myocardial [Ca2+]i. Our results suggest that the anti-beta-adrenoceptor antibody might increase myocardial [Ca2+]i and result in myocardial damage. The antibodies might activate receptor-gating Ca(2+)-channel, thereby causing myocardial [Ca2+]i rise and calcium overload. Early use of betaloc is recommended in the treatment of dilated cardiomyopathy.

Field trials of combined use of two species of mermithid nematodes to control Anopheles and Culex breeding in China

The field tests of combined use of Romanomermis yunanensis 2000-3000 larvae per sq m and Romanomermis sp 1000-2000 larvae per sq m in rice fields. Ponds and streams in four cities of China, resulted in 60.8-95.5% parasitism in Culex tritaeniorhynchus, Cx. quinquefasciatus, Anopheles sinensis and An. anthropophagus. This successful use of two species of Romanomermis together not only curb mosquito nuisance it also controls the major vectors of malaria, filariasis and encephalitis B in China.

[Determination of content of chlorpromazine hydrochloride in compound metamizole sodium microenema by acid-dye colorimetric method]

An acid-dye colormetric method was described for the determination of chlorpromazine hydrochloride in the compound preparation. The method was based on the reaction of chlorpromazine hydrochloride with methyl orange, to form a yellow complex, which then was extracted by chloroform and exhibited a maximum absorption at 424 nm. The optimal conditions for determination were selected by orthogonal design test. The linear range of this method was 20-120 micrograms/ml (r = 0.9997). The average recovery of the three sample solutions of different concentrations was 99.72% +/- 0.46% (n = 6). The other ingredients of preparation do not interfere with chlorpromazine determination. This method is more sensitive and accurate and can be used for quality control of this compound preparation.

Using multiple decrement models to estimate risk and morbidity from specific AIDS illnesses. Multicenter AIDS Cohort Study (MACS)

A simple non-parametric approach is developed to simultaneously estimate net incidence and morbidity time from specific AIDS illnesses in populations at high risk for death from these illnesses and other causes. The disease-death process has four-stages that can be recast as two sandwiching three-state multiple decrement processes. Non-parametric estimation of net incidence and morbidity time with error bounds are achieved from these sandwiching models through modification of methods from Aalen and Greenwood, and bootstrapping. An application to immunosuppressed HIV-1 infected homosexual men reveals that cytomegalovirus disease, Kaposi's sarcoma and Pneumocystis pneumonia are likely to occur and cause significant morbidity time.

Ryanodine-sensitive component of calcium transients evoked by nerve firing at presynaptic nerve terminals

Whether Ca2+ released from stores within the presynaptic nerve terminals also contributes to the Ca2+ elevation evoked by action potentials was tested in intact bullfrog sympathetic ganglia. Intraterminal Ca2+ transients (Delta[Ca2+]i) were evoked by electrical shocks to the presynaptic nerves at 20 Hz and were monitored by fura-2 fluorimetry. Ca2+ released through intraterminal ryanodine-sensitive channels accounted for 46% of the peak Ca2+ elevation. Moreover, in half of the terminals when intraterminal release was blocked by ryanodine, Delta[Ca2+]i reached a plateau at 200 +/- 24 nM. Because 20 Hz is a frequency favorable for the release of a neuropeptide, luteinizing hormone releasing hormone (LHRH) from these presynaptic nerve terminals, and because the threshold level for LHRH release is 186 nM, intraterminal Ca2+ release during nerve firing is likely to play a major role in regulating LHRH release. The intraterminal ryanodine channels were facilitated by caffeine as in other tissue. The releasable ryanodine-sensitive store could elevate the intraterminal [Ca2+] by an amount as high as 1.6 microM at a rate as fast as 250 nM/sec. The store could be refilled within 100 sec after a maximal discharge of its content by 20 Hz firing. Oscillation of [Ca2+]i evoked by 20 Hz nerve firing occurred in normal Ringer solution, in ryanodine, and in caffeine with a periodicity of approximately 10 sec. Besides the facilitatory effects on the ryanodine-sensitive channels, caffeine also had inhibitory effects on Delta[Ca2+]i via its action on a different process.

Longitudinal relation between smoking and white blood cells

Higher white blood cell counts in smokers compared with nonsmokers have been well documented, but the longitudinal relation between changes in smoking and changes in white blood cells has not been well described. Since 1984, data have been collected semiannually by the Multicenter AIDS Cohort Study (MACS), a four-center prospective cohort study of acquired immunodeficiency syndrome (AIDS) in homosexual men. The study population includes 2,435 participants who were human immunodeficiency virus (HIV) seronegative as of September 1994 and who contributed 20,918 person-visits for this analysis. For individuals who modified their smoking behavior, changes in white blood cell counts occurred primarily during the first 6 months following changes in the amount of cigarettes smoked. Among former smokers who resumed smoking, the extent of the increase in white blood cell count depended on the number of cigarettes smoked. Specifically, increases of 241, 340, and 740 cells/microliter were observed for smokers who resumed smoking < 1, 1 to < 2, and > or = 2 packs/day, respectively. Conversely, smokers who quit smoking had a decrease of white blood cell count: -32, -629, and -1,122 cells/microliter for men who previously smoked < 1, 1 to < 2, and > or = 2 packs/day, respectively. Long-term ex-smokers, however, still had higher white blood cell counts than did never smokers. There was a high within-individual correlation of white blood cell count in persons who reported a consistent level of smoking (i.e., average correlations between two white blood cell counts 6 years apart were 0.51 for never smokers, 0.48 for ex-smokers, 0.56 for men who smoked < 1 pack/day, and 0.43 for men who smoked > or = 1 pack/day). These analyses indicate an acute effect of changes in smoking on changes in white blood cell count, a residual effect of having been a smoker, and high long-term tracking for white blood cell count.

Genetic heterogeneity in hereditary breast cancer: role of BRCA1 and BRCA2

The common hereditary forms of breast cancer have been largely attributed to the inheritance of mutations in the BRCA1 or BRCA2 genes. However, it is not yet clear what proportion of hereditary breast cancer is explained by BRCA1 and BRCA2 or by some other unidentified susceptibility gene(s). We describe the proportion of hereditary breast cancer explained by BRCA1 or BRCA2 in a sample of North American hereditary breast cancers and assess the evidence for additional susceptibility genes that may confer hereditary breast or ovarian cancer risk. Twenty-three families were identified through two high-risk breast cancer research programs. Genetic analysis was undertaken to establish linkage between the breast or ovarian cancer cases and markers on chromosomes 17q (BRCA1) and 13q (BRCA2). Mutation analysis in the BRCA1 and BRCA2 genes was also undertaken in all families. The pattern of hereditary cancer in 14 (61%) of the 23 families studied was attributed to BRCA1 by a combination of linkage and mutation analyses. No families were attributed to BRCA2. Five families (22%) provided evidence against linkage to both BRCA1 and BRCA2. No BRCA1 or BRCA2 mutations were detected in these five families. The BRCA1 or BRCA2 status of four families (17%) could not be determined. BRCA1 and BRCA2 probably explain the majority of hereditary breast cancer that exists in the North American population. However, one or more additional genes may yet be found that explain some proportion of hereditary breast cancer.

[Experimental study of adoptive immunotherapy for adenoid cystic carcinoma of the salivary gland]

To study adoptive immunotherapy for adenoid cystic carcinoma of the salivary gland, we evaluate the influence of TNF-alpha or IFN-gamma on the activity of LAK cells when they acted at different stages of LAK cells killing target cells. The results in vitro experiment showed that ACC-2 was susceptible to LAK cytotoxicity. Both TNF-alpha and IFN-gamma could be an enhancer to augment IL-2-induced LAK cytotoxity against ACC-2, TNF-alpha should be used to induce LAK cells, but IFN-gamma is suitable to pretreat target cells ACC-2.

Role of tyrosine kinase pathways in ETB receptor activation of NHE3

Endothelin-1 (ET-1) binding to ETB receptors increases the activity of the apical membrane Na+/H+ antiporter (NHE3) of renal proximal tubule and cultured OKP cells. In OKPETB6 cells, a clonal cell line of OKP cells that overexpresses ETB receptors, ET-1-induced increases in Na+/H+ antiporter activity are mediated 50% by Ca2(+)-dependent pathways and 50% by tyrosine kinase pathways. ET-1 induces tyrosine phosphorylation of proteins of 68, 110, 125, 130, and 210 kDa. ET-1-induced tyrosine phosphorylation is mediated by the ETB receptor and is not dependent on increases in cell Ca2+ or protein kinase C. The 68-, 110-, 125-, and 130-kDa phosphoproteins are cytosolic, whereas the 210-kDa phosphoprotein is an integral membrane protein. Immunoprecipitation studies showed that the 68-kDa protein is paxillin and the 125-kDa protein is p125FAK (focal adhesion kinase). Cytochalasin D, which disrupts focal adhesions, prevented ET-1-induced tyrosine phosphorylation of paxillin, p110, p125FAK, and p130 but did not prevent tyrosine phosphorylation of p210 and did not prevent ET-1-induced increases in Na+/H+ antiporter activity. Thus 50% of ETB receptor-induced Na+/H+ antiporter activation is mediated by tyrosine kinase pathways, possibly involving p210. ETB receptor activation also induces tyrosine phosphorylation of focal adhesion proteins, but this is not required for antiporter activation.

Generation of an integrated transcription map of the BRCA2 region on chromosome 13q12-q13

An integrated approach involving physical mapping, identification of transcribed sequences, and computational analysis of genomic sequence was used to generate a detailed transcription map of the 1. 0-Mb region containing the breast cancer susceptibility locus BRCA2 on chromosome 13q12-q13. This region is included in the genetic interval bounded by D13S1444 and D13S310. Retrieved sequences from exon amplification or hybrid selection procedures were grouped into physical intervals and subsequently grouped into transcription units by clone overlap. Overlap was established by direct hybridization, cDNA library screening, PCR cDNA linking (island hopping), and/or sequence alignment. Extensive genomic sequencing was performed in an effort to understand transcription unit organization. In total, approximately 500 kb of genomic sequence was completed. The transcription units were further characterized by hybridization to RNA from a series of human tissues. Evidence for seven genes, two putative pseudogenes, and nine additional putative transcription units was obtained. One of the transcription units was recently identified as BRCA2 but all others are novel genes of unknown function as only limited alignment to sequences in public databases was observed. One large gene with a transcript size of 10.7 kb showed significant similarity to a gene predicted by the Caenorhabditis elegans genome and the Saccharomyces cerevisiae genome sequencing efforts, while another contained a motif sequence similar to the human 2',3' cyclic nucleotide 3' phosphodiesterase gene. Several retrieved transcribed sequences were not aligned into transcription units because no corresponding cDNAs were obtained when screening libraries or because of a lack of definitive evidence for splicing signals or putative coding sequence based on computational analysis. However, the presence of additional genes in the BRCA2 interval is suggested as groups of putative exons and hybrid selected clones that were transcribed in consistent orientations could be localized to common physical intervals.

Occurrence of cytomegalovirus retinitis after human immunodeficiency virus immunosuppression

OBJECTIVE

To estimate the incidence and prevalence of cytomegalovirus retinitis (CMV-R) in late-stage human immunodeficiency virus type 1 disease.

DESIGN

Cohort study.

SETTING

The Multicenter AIDS Cohort Study, an ongoing 10-year study of human immunodeficiency virus type 1-infected homosexual men with semiannual visits and CD4+ cell testing.

STUDY PARTICIPANTS

Three hundred sixty-seven human immunodeficiency virus type 1-infected men from the Multicenter AIDS Cohort Study who were receiving zidovudine and Pneumocystis carinii prophylaxis and who had CD4+ cell counts fall below 0.10 x 10(9)/L (100/microL).

MAIN OUTCOME MEASURES

Kaplan-Meier-type estimates for various longitudinal quantifications of incidence and prevalence of CMV-R were obtained.

RESULTS

Among these 367 individuals, cytomegalovirus disease developed in 103, of whom 73 (71%) had ocular complications. At 4 years after the first CD4 cell count ( < 0.10 x 10(9)/L), the probability for these subjects to have (1) remained living without CMV-R was 11%, (2) died without experiencing CMV-R was 66%, (3) experienced CMV-R and be living was 6%, and (4) experienced CMV-R and died was 18%. During these 4 years, there was a 25% chance for the development of CMV-R and, on average, 0.211 person-years of CMV-R morbidity. Among those subjects in whom CMV-R developed, about 19% did have CMV-R before a CD4+ cell count of less than 0.05 x 10(9)/L ( < 50/microL) was observed, and 81% had CMV-R after the CD4+ cell count reached this threshold.

CONCLUSION

These estimates may be relevant to current clinical practice and help in allocating resources and planning for treatment and prophylaxis against cytomegalovirus disease.

Projecting disease when death is likely

Projection disease incidence, prevalence, and net morbidity is often needed when individuals are likely to die, either disease free or after the disease has developed. Examples of this include remission of cancer or heart disease in elderly people who can die from these or other causes and occurrence of a particular acquired immune deficiency syndrome illness in human immunodeficiency virus type 1 (HIV-1) disease. Death is not an ancillary event but, rather, indicates either and end to disease morbidity or an end to risk to ever develop the disease. Thus, time to disease survival analyses that censor disease-free individuals at death can produce misleading results. The paper describes several useful quantifications of disease and death for this setting. A paradigm that utilizes Kaplan-Meier functions to estimate these quantities is introduced. The approach anchors on a four-stage disease/death model: stage A, living without disease; stage B, dead without ever developing disease; stage C, developed the disease and living; and stage D, dead after developing the disease. An application is made to projecting cytomegalovirus disease in a cohort of HIV-1-infected users of zidovudine and Pneumocystis prophylaxis from the Multicenter AIDS Cohort Study (MACS) during 1989-1993. At 3 years after a CD4+ count below 100/microliters, a man had an 18.7%, 46.3%, 5.3% or 29.9% chance, respectively, to be in stage A, B, C, or D. This man, on average, had 0.28 years of cytomegalovirus morbidity during these 3 years.

BRCA2 germline mutations in male breast cancer cases and breast cancer families

The breast cancer susceptibility gene, BRCA2 on chromosome 13q12-13, was recently isolated. Mutations in BRCA2 are thought to account for as much as 35% of all inherited breast cancer as wall as a proportion of inherited ovarian cancer. Many BRCA2-linked families also contain cases of male breast cancer. We have analysed germline DNA from 50 males with breast cancer (unselected for family history) and 26 individuals from site-specific female breast and breast-ovarian cancer families for mutations in BRCA2. All 17 breast-ovarian cancer families have been screened for BRCA1 coding region mutations and none were detected. Conformation-sensitive gel electrophoresis (CSGE) analysis of PCR-amplified DNA followed by direct sequencing was used to detect sequence variants. Three of eleven individuals carry the same mutation, all are of Ashkenazi Jewish descent, supporting the observation by Neuhausen et al. in this issue that there is a common mutation in this population. Eleven truncating mutations and nine polymorphisms were identified -- all were coding region variants. No loss-of-transcript mutations were identified in the sixteen samples for which this analysis was possible. Seven of the nine disease-associated mutations were detected in the 50 men with breast cancers; for thus in our series, BRCA2 mutations account for 14% of male breast cancer, all but one of which had a family history of male and/or female breast cancer.

Survival from early, intermediate, and late stages of HIV infection

OBJECTIVE

To estimate expected survival time among homosexual men infected with the human immunodeficiency virus type 1 (HIV-1) by (1) the calendar period before (1985-1988) and after (1989-1993) the widespread availability of acquired immunodeficiency syndrome (AIDS) treatments with antiretroviral and prophylactic interventions, and (2) stage of HIV disease.

DESIGN

A prospective cohort study. A group of HIV-1-infected homosexual men were followed from July 1985 through June 1993 and evaluated every 6 months for the presence of clinical symptoms and measurement of the CD4 cell count. To measure the effectiveness of AIDS therapies in this nonrandomized study, we used 2 calendar periods as proxy measures of relative intensity of exposure to antiretroviral therapy. Stage of infection was defined by CD4 cell count and presence of HIV-related clinical symptoms or AIDS.

SETTING AND STUDY PARTICIPANTS

Homosexual men infected with HIV-1 from the Multicenter AIDS Cohort Study.

MAIN OUTCOME MEASURE

Survival time based on stage of HIV infection.

RESULTS

The percentage of HIV-1-infected individuals free of AIDS and clinical symptoms at baseline who survived 2.5 years according to baseline CD4 cell counts of 0 to 0.100, 0.101 to 0.200, and 0.201 to 0.350 x 10(9)/L was 22%, 53%, and 83%, respectively, for the 1985-1988 calendar period, compared with 54%, 71%, and 91%, respectively, for men in the 1989-1993 calendar period. Among men free of AIDS with CD4 cell counts of greater than 0.350 x 10(9)/L, the relative hazard of mortality was 1.6 to 2.3 times higher for those with clinical symptoms compared with those free of clinical symptoms.

CONCLUSIONS

Survival of AIDS-free HIV-1-infected individuals with CD4 cell counts of less than 0.350 x 10(9)/L has improved since antiretroviral and HIV prophylactic treatments have become available, but the long-term prognosis remains poor.

Endothelin(B) receptor activates NHE-3 by a Ca2+-dependent pathway in OKP cells

To examine the mechanisms by which endothelin (ET) regulates the Na/H antiporter isoform, NHE-3, OKP cells were stably transfected with ET(A) and ET(B) receptor cDNA. In cells overexpressing ET(B), but not ET(A) receptors, ET-1 increased Na/H antiporter activity (JNa/H). This effect was inhibited by a nonselective endothelin receptor blocker and by a selective ET(B) receptor blocker but was not inhibited by an ET(A) selective receptor blocker. In ET(B)-overexpressing cells, 10(-8) M ET-1 inhibited adenylyl cyclase, but protein kinase A inhibition and pertussis toxin pretreatment did not affect Na/H antiporter activation by ET-1. ET-1 caused a transient increase in cell [Ca2+], followed by a sustained increase. Increases in cell [Ca2+] were partially inhibited by pertussis toxin. ET-1-induced increases in J(Na/H) were 50% inhibited by clamping cell [Ca2+] low with BAPTA, and by KN62, a Ca-calmodulin kinase inhibitor. Inhibitors of protein kinase C, cyclooxygenase, lipoxygenase, and cytochrome P450 and cyclic GMP were without effect. In ET(A)-overexpressing cells, ET-1 increased cell [Ca2+] but did not increase JNa/H. In summary, binding of ET-1 to ET(B) receptors increases Na/H antiporter activity in OKP cells, an effect mediated in part by increases in cell [Ca2+] and Ca-calmodulin kinase. Increases in cell [Ca2+] are not sufficient for Na/H antiporter activation.

The complete BRCA2 gene and mutations in chromosome 13q-linked kindreds

Breast carcinoma is the most common malignancy among women in developed countries. Because family history remains the strongest single predictor of breast cancer risk, attention has focused on the role of highly penetrant, dominantly inherited genes in cancer-prone kindreds (1). BRCA1 was localized to chromosome 17 through analysis of a set of high-risk kindreds (2), and then identified four years later by a positional cloning strategy (3). BRCA2 was mapped to chromosomal 13q at about the same time (4). Just fifteen months later, Wooster et al. (5) reported a partial BRCA2 sequence and six mutations predicted to cause truncation of the BRCA2 protein. While these findings provide strong evidence that the identified gene corresponds to BRCA2, only two thirds of the coding sequence and 8 out of 27 exons were isolated and screened; consequently, several questions remained unanswered regarding the nature of BRCA2 and the frequency of mutations in 13q-linked families. We have now determined the complete coding sequence and exonic structure of BRCA2 (GenBank accession #U43746), and examined its pattern of expression. Here, we provide sequences for a set of PCR primers sufficient to screen the entire coding sequence of BRCA2 using genomic DNA. We also report a mutational analysis of BRCA2 in families selected on the basis of linkage analysis and/or the presence of one or more cases of male breast cancer. Together with the specific mutations described previously, our data provide preliminary insight into the BRCA2 mutation profile.

[Intestinal lymphatic circulation is one of the important portals for microbial translocation after thermal injury]

The goal of this study was to determine whether the bacteria and endotoxin from GI tract could pass through the intestinal lymph circulation to the systemic circulation after severe thermal injury. Lymphatic fistula of intestine was created in 46 Wistar rats the rats were then divided randomly in scald and control groups. In scald group, animals were sustained with 30% TBSA full-thickness scald. The items studied were, the dynamic changes in intestinal lymph endotoxin level, the qualitative and quantitative bacterial culture, and pathological alterations in ileal mucosa within 24 hours postburn. Results showed that the levels of intestinal lymph endotoxin and the positive culture rate and counting of bacteria were evidently increased, and ileal mucosal lacteals were dilated and epithelial cells were necrotic and denudated in scald group. These suggested that the intestinal lymph circulation is one of the important portals for endotoxin and microbial translocation after severe thermal injury, and the intestinal mucosal damage is an important factor in pathogenesis.

Cardiac cytotoxic mechanism mediated by antibodies against myocardial mitochondrial ADP/ATP carrier in patients with dilated cardiomyopathy

OBJECTIVE

To investigate mechanism of the antibody-mediated cardiac cytotoxicity and clinical significance in dilated cardiomyopathy (DCM), and study the effects of the antibodies against the myocardial mitochondrial ADP / ATP carrier from sera of patients with dilated cardiomyopathy on the guinea pig ventricular myocytes.

PATIENTS AND METHODS

This study included 18 patients with DCM (12 men and 6 women), with mean age of 43 years. Control group included 18 health donors, (9 men and 9 women), with mean age of 32 years. The antibodies against the ADP / ATP carrier and cell membrane 52 000 peptide were examined by immunoblotting. The antibody-mediated cardiac cytotoxicity was studied with the cytotoxic test and whole cell patch-clamp technique.

RESULTS

The antibodies against myocardial mitochondrial ADP / ATP carrier and cell membrane 52 000 peptide were positive in 18 patients with DCM, while negative in controls. The antibodies induced cytotoxic damage with time-dependent and enhanced Ca-current in cardiac myocytes. The increasing amplitude of peak Ca(2+)-current was 100 pA-840 pA (n = 8) in different dilution of the antibodies. The effect of the antibodies might be inhibited by verapamil, and were null in controls (n = 4).

CONCLUSIONS

The above findings suggest that an increase in the antibody-mediated Ca(2+)-current of cardiac myocytes is related to the cytotoxic damage in dilated cardiomyopathy.

[Effects of temperature on the viability and infectivity of preparasitic larvae of Romanomermis yuanenesis]

Romanomermis yuanenesis (Mermithidae: Nematoda) was found in Henan, China (Song and Peng, 1987), which has a broad host range in Culicinae mosquito and has been used successfully in field test for control of culex tritaeniorhynchus, culex fatigans and Aedes albopictus in Sichuan, Yunnan, Guangxi and Henan Provinces. This study was attempted to determine the viability and infectivity of preparasitic larvae in various temperatures. The cultures containing R. yuanenesis eggs were flooded 2h with distilled water, filtered and blocked with 1% agarose. Put the filter paper into water, then the motile preparasites separated from the unhatched eggs and got through the agarose membrane into water. About 200ml water containing preparasites free from eggs were held at 26 degrees C-28 degrees C, 16 degrees C-18 degrees C and -2 degrees C to 2 degrees C for test. The motility or lack of motility was used as the criterion to distinguish the living and dead nematodes. The rate of infection of mosquitoes and the rate of parasitism of nematodes were used to show the infectivity of the preserved preparasites. The results showed that at -2 degrees C to 2 degrees C, more than 90% of preparasitic larvae of R. yuanenesis survived for 8 days and the rate of mosquito infection was 87.5% to 100%, but at 26 degrees C-28 degrees C and 16 degrees C-18 degrees C the survival times of 90% preparasites were only 24 hours and 48 hours respectively. It indicates the low temperature preservation may prolong the survival time and keep the infectivity of these preparasitic larvae.

Hepatic biotransformation in rodents and physicochemical properties of 23(R)-hydroxychenodeoxycholic acid, a natural alpha-hydroxy bile acid

The hepatic biotransformation in the rat and hamster of 23(R)-hydroxychenodeoxycholic acid (23(R)OH-CDCA), the alpha-hydroxy derivative of CDCA, was defined; some physiological and physicochemical properties were also assessed. 23(R)OH-CDCA was isolated from duck bile; [24-14C]23(R)OH-CDCA was synthesized. The compound was administered intravenously to anesthetized biliary fistula rats at doses of 1, 3, or 5 mu mol/kg-min and to hamsters at 3 mu mol/min-kg. Biliary bile acids and radioactivity were analyzed by thin-layer chromatography (TLC), high pressure liquid chromatography (HPLC), and gas chromatography-mass spectrometry (GC-MS). Recovery of radioactivity in bile was incomplete (50-70% of infused dose); some was also recovered as breath 14CO2. Radioactivity in bile was present as unchanged compound (25-50%, dose-dependent) and its conjugates (with taurine, with glycine, or with glucuronate). Nor-CDCA (C23) was present in bile (in both unconjugated and conjugated form), indicating that 23(R)OH-CDCA had undergone oxidative decarboxylation (alpha-oxidation) with loss of the C-24 carboxyl group. The alpha-oxidation was 20 +/- 5% (mean +/- SD) of administered dose in the rat and was not dose-dependent; in hamsters, alpha-oxidation was 35 +/- 8%. In rats, the S isomer of 23OH-CDCA also underwent alpha-oxidation (10 +/- 2%). Nor-CDCA also underwent 6beta-hydroxylation to form nor-alpha-muricholic acid, as well as reduction of its C-23 carboxyl group to form the C23 alcohol. The taurine conjugate of 23(R)OH-CDCA [23(R)OH-CDC-tau] was prepared synthetically and characterized by 1H-NMR. By surface tension measurements, it had a critical micellization concentration (CMC) of 3.5 mM (in 0.15 M Na+), as compared to 1.8 mM for CDC-taurine. Aqueous solubility of 23(R)OH-CDCA increased markedly above pH 5, compared to pH 7 for CDCA. When incubated with cholylglycine hydrolase, 23(R)OH-CDC-tau was deconjugated at a rate one-fourth that of CDC-tau. It is concluded that the presence of a 23(R)-hydroxyl group in a 3alpha, 7alpha-dihydroxy bile acid alters its metabolism in the rodent hepatocyte, as evidenced by inefficient conjugation with taurine or glycine, alpha-oxidation to nor (C23) bile acid, and reduction of the nor bile acid to the primary alcohol. The taurine conjugate of 23(R)OH-CDCA, a major biliary bile acid of marine mammals and wading birds, is a biological detergent with properties superior to those of the taurine conjugate of CDCA. Natural C23 nor-bile acids may be formed by alpha-oxidation of alpha-hydroxy C24 bile acids.

Immunoregulatory role of neurotransmitters

The nervous and endocrine systems modulate the immune system functions through releasing neurotransmitters, neuropeptides and endocrine hormones as they regulate the other physiological functions. The immune system in turn communicates with the nervous and endocrine systems through secreting immunocompetent substances. In this report we review our concepts and evidence concerning the immunoregulatory role of acetylcholine (ACh) and monoamine neurotransmitters which include noradrenaline (NA), 5-hydroxytryptamine (5-HT) and dopamine (DA). The immunoregulatory role comprises two aspects, the modulation of immune functions by neurotransmitters and the effect of the immune system on nervous system functions. The inhibition of ACh biosynthesis in the central nervous system (CNS) caused the enhancement of the humoral immune response of rats to sheep red blood cells (SRBC); by contrast, the inhibition of acetyl-cholinesterase (AChE) activity in the CNS resulted in the suppression of the immune response. It seems that ACh in the brain plays an immunoinhibitory role. The role can be blocked by atropine, a muscarinic antagonist, but not by hexamethonium, a nicotinic antagonist. During the humoral immune response (days 3-6 after SRBC injection), activity of AChE in the hypothalamus and hippocampus was strikingly lower. It is suggested that a functional connection is present in the ACh of the brain and the immune system. In vitro, ACh at 10(-9) to 10(-4) mol/l dose range significantly strengthened the spleen cell proliferation induced by concanavalin (Con A). The action of ACh only occurred either before or just after T lymphocytes were activated through muscarinic cholinergic receptors. In vivo, the depletion of monoamine neurotransmitters or only NA in the CNS caused the impairment of the anti-SRBC response of rats. During the phases of days 2-7 post-immunization, the metabolic alterations of NA, 5-HT and DA emerged in the CNS and the lymphoid organs of rats, which mainly exhibited that in the peak periods of the antibody response, the metabolism of the monoamine neurotransmitters in the hypothalamus and hippocampus was markedly increased, but NA content in the spleen and thymus was significantly decreased. These results provide evidence for the bidirectional information exchange network between the monoamine neurotransmitters and the immune system. Exposure to NA (at 10(-8)-10(-5) mol/l concentration range) in vitro was shown to inhibit the Con A-induced proliferation of the rat spleen cells. This effect of NA was related to the early events involved in the initiation of T cell proliferation and was mediated by either alpha- or beta-adrenergic receptors. The evidence that altering 5-HT level in the central or peripheral nervous systems through various ways of administering the drugs to regulate 5-HT biosynthesis led to the variations of the antibody response, and that cyproheptadine, an antagonist of serotoninergic receptors, can block the action of 5-HT show that 5-HT may exert an immunoinhibitory effect, which appears to be mediated via the peripheral mechanism to relate to the 5-HT receptors. However, the antibody response can cause changes in 5-HT metabolism in the CNS. The possible reasons for these results are discussed. Collectively, the antibody response arouses the metabolic variations of ACh, NA, 5-HT and DA in the central and peripheral nervous systems and then, these alterations can in turn influence immune function through neurotransmitter relevant receptors present on the immunocytes. The purpose of this interaction is most likely to maintain the homeostasis of the immune and other physiological functions.

Reversal of the antinatriuretic effect of prostaglandin E2 by verapamil in the rat

Previous studies have demonstrated that prostaglandin E2 (PGE2) infusion increases intrarenal angiotensin-II (ANG-II) formation and decreases sodium excretion in the rat. PGE2 infusion may have direct tubular effects or indirect effects through increased intrarenal ANG-II. In the present study, the calcium channel blocker verapamil was used to determine whether it would reverse the PGE2-induced decrease in sodium excretion. To minimize any systemic and hemodynamic influences, verapamil and PGE2 were infused directly into the renal interstitium via a chronically implanted matrix. Fractional sodium excretion (FENa), glomerular filtration rate (GFR), mean arterial pressure (MAP), and plasma renin activity (PRA) were measured before and during renal interstitial infusion of PGE2 (10(-5) M) and/or verapamil (10(-3) M) in rats pretreated with indomethacin. The renal interstitial infusion of PGE2 alone significantly decreased FENa (delta-1.0 +/- 0.2%), whereas the addition of verapamil reversed the effect of PGE2 and significantly increased FENa (delta 2.6 +/- 0.3%, n = 9). The renal interstitial infusion of verapamil alone markedly increased FENa (delta 1.7 +/- 0.3%, n = 7), and this natriuresis was accompanied by a significant decrease in PRA (delta-0.6 +/- 0.1 ng/ml/h, p < 0.05). The addition of PGE2 to the interstitial infusion did not further affect FENa or PRA. There was a significant difference between the effect of interstitial PGE2 infusion and interstitial PGE2 infusion and interstitial verapamil infusion on PRa (delta 1.9 +/- 0.8 vs. delta -0.6 +/- 0.1 ng/ml/h, p < 0.05). GFR and MAP remained unchanged in response to the renal interstitial infusion of PGE2 and/or verapamil. In conclusion, verapamil reversed the PGE2-induced antinatriuresis in the rat.

Factors accounting for different responses of pulmonary and cerebral vessels to hypoxia

The roles of sympathicus, sensory neuropeptides (SNP), cyclooxygenase metabolites (COX-M), lipoxygenase metabolites (LOX-M), endothelium derived relaxing factor (EDRF), reactive oxygen (ROS) and potassium channels (PC) in the hypoxic pulmonary vasoconstriction (HPV) and hypoxic cerebral vasodilation (HCVD) were investigated in intact rats, rabbits and dogs. The results showed that during hypoxia, the excitation of sympathicus caused a constriction of both pulmonary and cerebral vessels, while SNP, EDRF and the opening of voltage sensitive PC caused the dilation of both of them; LOX-M mediated HPV and HCVD, COX-M might serve as their modulators; the blockade of ATP sensitive PC induced by hypoxia mediated HPV, but had no effect on HCVD; the reduction of O2-. in the lung might potentiate HPV, however, O2-. remained unchanged in brain during hypoxia. It is suggested that the alterations of LOX-M, ROS and the ATP sensitive PC are the factors accounting for the difference in the response of pulmonary and cerebral vessels to hypoxia.

[The effect of intra-aortic balloon pumping in case of left main coronary artery stenosis]

In order to improve perfusion of coronary artery in case of coronary artery stenosis, effect of intra-aortic balloon pumping (IABP) on coronary blood flow (CBF) was investigated. To this end hemodynamic parameters of heart functions with and without stenosis were analysed under IABP. Hemodynamic effect of IABP was obviously influenced by the coronary artery stenosis.

Comparison of systemic and direct intrarenal angiotensin II blockade on sodium excretion in rats

To dissociate the renal effects from the systemic effects of angiotensin II blockade, the present study was designed to determine the effects of systemic and renal interstitial infusion of the specific angiotensin II (ANG II) receptor antagonist, losartan, on blood pressure and sodium excretion in rats fed a low-, normal, or high-sodium diet. Fractional sodium excretion (FENa) and mean arterial pressure (MAP) were measured in rats before and during systemic infusion of losartan (10 mg/kg) or renal interstitial infusion of losartan (3 mg/kg) by means of a chronically implanted matrix. In rats fed a low- or normal sodium diet, systemic infusion of losartan markedly decreased MAP (delta -21 +/- 2, delta -10 +/- 2 mmHg, respectively; P < 0.05) with an accompanying fall in FENa (delta -0.10 +/- 0.05, delta -0.91 +/- 0.40%, respectively; P < 0.05). In contrast, preferential blockade of renal ANG II with renal interstitial losartan infusion resulted in an increase in FENa (delta 0.13 +/- 0.04, delta 0.95 +/- 0.45%, respectively; P < 0.05) and no significant change in MAP. In rats fed a high-sodium diet, both systemic and renal interstitial infusion of losartan increased FENa (delta 1.90 +/- 0.26, delta 1.40 +/- 0.56%, respectively; P < 0.05). Although systemic infusion of losartan decreased MAP (delta -4.4 +/- 0.6 mmHg, P < 0.05) in rats fed a high-sodium diet, the reduction in MAP was much less than that in rats fed a low- and normal sodium diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of a polymer-enzyme immunoassay method and its application

Both poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)-antibody (PINP-Ab)-labelled enzyme adhered quickly and tightly to cellulose acetate/nitrate membrane either below (less efficiently) or above (more efficiently) the lower critical solution temperature, and the retention of PINP-Ab on the membrane increased over 30-fold when compared with the unconjugated Ab. These characteristics were used to develop a novel polymer-enzyme-linked immunoassay method: homogeneous antigen-antibody immune-complexation reaction and a heterogeneous separation process. By using a simple horseradish-peroxidase-labelled antibody as a probe, we applied this method to the detection of human serum hepatitis B surface antigen (HBsAg). This immunoassay system can detect as little as 1 ng/ml of HBsAg. The advantages of this method are: (a) fast homogeneous immune complexation; (b) a rapid heterogeneous separation process; (c) high sensitivity; and (d) low non-specific background.

Changes of cellular morphology and nuclear DNA content in different nasopharyngeal epithelium from different patients

Cellular morphology and nuclear DNA content were measured with point-counting technique and flow cytometry (FCM) respectively in normal nasopharyngeal epithelium (NE), tissue adjacent to carcinoma (ATC) and nasopharyngeal carcinoma (NPC). The results showed that all 20 patients with NE showed diploid, whereas 38 (38%) of 101 patients with NPC, 7 (58%) of 12 patients with recurrent NPC, 6 (30%) of 20 patients with ATC and 2 (33%) of 6 patients with NE positive to EBVCA-IgA test showed nondiploid. A total of 19 morphometric parameters of the cell were measured and calculated. The results showed that with malignant transformation of NE, most of the cellular morphometric parameters gradually increased in numerical values while no marked difference was shown between normal NE and simple hyperplasia or metaplasia in terms of cytomorphometric characteristics. Most of the parameters in dysplasia changed significantly as compared with those normal NE, simple hyperplasia or metaplasia and NPC groups. Cytomorphometric analysis seems to give strong support to the concept that dysplasia is among the transitional stages of disease process between normal NE and NPC. Our results show that morphometric analysis and FCM may offer valuable and objective criteria in the early diagnosis of NPC and premalignant disease.

Predictors for failure of Pneumocystis carinii pneumonia prophylaxis. Multicenter AIDS Cohort Study

OBJECTIVE

To identify clinical and epidemiological factors associated with failure of Pneumocystis carinii pneumonia (PCP) prophylaxis in those receiving primary and secondary prophylaxis.

DESIGN

Longitudinal cohort study of participants infected with human immunodeficiency virus type 1 in the Multicenter AIDS Cohort Study who used PCP prophylaxis regimens after their T-helper lymphocyte counts had decreased to less than 0.200 x 10(9)/L (200/microL).

MAIN OUTCOME MEASURE

Occurrence or recurrence of PCP.

RESULTS

A total of 476 participants reported taking one or more of the following regimens: trimethoprim-sulfamethoxazole (TMP-SMX), dapsone, and/or aerosolized pentamidine--367 as primary prophylaxis and 109 as secondary prophylaxis after a previous episode of PCP. A total of 92 (20%) developed PCP despite prophylaxis. The mean failure rates per person-year of follow-up were 16.0% for those receiving primary prophylaxis and 12.1% for those receiving secondary prophylaxis (P = .19). Median times to death after initiation of primary or secondary prophylaxis were 2.0 and 1.2 years, respectively. The main predictor for failure of PCP prophylaxis was profound T-helper lymphocytopenia; 86% of failures occurred after T-helper cell counts decreased to less than 0.075 x 10(9)/L and 76% occurred after counts decreased to less than 0.050 x 10(9)/L. In multivariate time-dependent analysis, when compared with counts between 0.100 x 10(9)/L and 0.200 x 10(9)/L, the risk ratio for failure with counts less than 0.050 x 10(9)/L was 2.90 (P < .001). Once T-helper cell counts were considered, fever was the only other health status indicator that predicted subsequent PCP (ie, a time-dependent risk ratio of 2.22; P = .01). Use of TMP-SMX as the prophylaxis regimen was protective but did not eliminate failure (ie, a time-dependent risk ratio of 0.55; P = .03).

CONCLUSIONS

These findings strongly support identifying improved methods of PCP prophylaxis once T-helper cell counts decrease to less than 0.075 x 10(9)/L or 0.100 x 10(9)/L. Given this severe degree of immunosuppression, an inherently more effective regimen against P carinii is required.

High-specificity neurological localization using a connectionist model

Most previous connectionist models for diagnosis have been developed using error backpropagation. While these systems function reasonably well, they have been limited by their need for a large database of test cases, to situations where a single disorder is present, and by the large number of connections required between fully-connected sets of processing units. Here we describe a recently developed connectionist model that overcomes these limitations. This approach can reuse existing causal knowledge bases, works well in situations where multiple disorders can occur simultaneously, and does not require fully-connected sets of processing units. We demonstrate that the accuracy of this model is comparable to that of more conventional AI programs using the same knowledge base in determining precisely the site of brain damage in a group of 50 stroke patients. These results support the conclusion that connectionist models can effectively use pre-existing causal knowledge bases from AI systems, and that they can function accurately when handling actual clinical problems.

Glycine and GABAA antagonists reduce the inhibition of primate spinothalamic tract neurons produced by stimulation in periaqueductal gray

Amino acids are demonstrated to be important neurotransmitters mediating the inhibitory transmission from nucleus raphe magnus to spinal nociceptive dorsal horn neurons. In this study, the role of glycine and GABA in the inhibitory processes evoked by stimulation in periaqueductal gray (PAG) of responses of primate spinothalamic tract (STT) neurons to cutaneous mechanical and thermal stimuli was investigated by examining the effects of strychnine and bicuculline, antagonists of glycine and GABAA receptors, respectively, introduced into the dorsal horn through a microdialysis fiber. The inhibitory effects of iontophoretic application of glycine and GABAA agonists on STT cell activity evoked by noxious mechanical stimulation of the skin were selectively blocked by their specific antagonist, strychnine or bicuculline, infused into the dorsal horn. Similarly, intra-spinal application of strychnine or bicuculline resulted in a significant reduction in the PAG stimulation-induced inhibition of responses of STT cells to cutaneous stimuli. This reduction was mainly on the PAG-induced inhibition of the responses to noxious mechanical stimuli. Our results suggest that glycinergic and GABAergic inhibitory interneurons in the spinal cord dorsal horn synapsing on STT cells are activated during stimulation in PAG and contribute to descending antinociceptive actions.

Markers of thromboembolization in a bovine ex vivo left ventricular assist device model

The production of blood microemboli (BME) was studied using an ex vivo exteriorized left ventricular assist device (LVAD) model in calves. Each of eight calves received a series of three LVADs, each operating for 24 hr. Blood microemboli were measured directly by a laser (624 nm and 828 nm) light scattering microemboli detection (LSMD) system through the LVAD outflow cannula and by constant pressure filtration (CPF) of blood samples from the LVAD outflow cannula. Hematologic parameters were also measured. After LVAD removal, perivalvular thrombi were evaluated using polar coordinate mapping. The average LSMD and CPF results correlated. For example, in one series of three calves, one ventricle exhibited significantly greater thrombogenesis than did the other ventricles, as indicated by both the LSMD and CPF results. In a series of five calves, one calf developed an abnormally high activated thromboplastin time (APTT), even in the absence of heparin. For two of the three ventricles tested in that calf, microemboli concentration (CPF), Factor XII activity, level of fibrin degradation products (FDP), and accumulated thrombus were significantly lower than for the other calves. The whole blood viscosity (WBV, at 230 s-1) in this calf also decreased to lower values than were seen with the other calves.

Hyperglycemia delays rostral initiation sites during neural tube closure

Neural tube defects contribute greatly to perinatal loss, physical handicap, mental retardation and other developmental defects, yet the mechanisms through which they occur are poorly understood. One hindrance to the study of these defects at the cellular and molecular levels is the low frequency with which they arise in susceptible animals. The present study utilizes a culture system for the study of rodent exencephaly, an animal model of human anencephaly, in which a high frequency of affected animals are obtained by culture in hyperglycemic rat serum. Rat embryos were dissected at day 9.5 from timed-pregnant Sprague-Dawley dams and cultured under standard conditions developed by New [Biol. Rev. (1978) 53,81-122]. Embryos cultured under elevated glucose conditions are able to close the caudal neural tube with the failure of neural tube closure limited to the rostral neuralepithelium. In this report we present the novel finding that, although at the end of culture frequently only the hindbrain region remains open, the normal sequence of events expected during rostral closure anterior to the hindbrain is markedly delayed. In embryos cultured in hyperglycemic serum, both rostral initiation sites II and III are significantly delayed. The degree of delay increases with increasing glucose concentration in the culture medium. These studies support the use of this defined in vitro model of anencephaly for studies of the molecular and cellular bases underlying the failure of hindbrain closure and demonstrate that sufficient numbers of affected animals can be produced to obtain significant results.(ABSTRACT TRUNCATED AT 250 WORDS)