A neutral glycoprotease of Pasteurella haemolytica A1 specifically cleaves O-sialoglycoproteins.

A neutral metalloprotease with marked specificity for an O-sialoglycoprotein has been isolated from culture supernatants of Pasteurella haemolytica A1. The 35-kDa enzyme cleaves human erythrocyte glycophorin A, which is O glycosylated, but does not cleave N-glycosylated proteins or nonglycosylated proteins. Glycophorin A was cleaved when it was present in situ in erythrocyte ghost plasma membranes or when it was free in solution. The glycoprotease did not hydrolyze glycophorin A from which sialate residues had been removed by neuraminidase treatment. An immobilized preparation of the enzyme cleaved glycophorin A at several positions, with a major site of cleavage at Arg-31-Asp-32. The glycoprotease is inhibited by EDTA, citrate, and ascorbate, but inhibition appears to be due to the masking of metal ion activators rather than to their removal. The enzyme is not inhibited by phosphoramidon, an inhibitor of other bacterial neutral metalloproteases.     

Frequent ongoing T-cell receptor rearrangements in childhood B- precursor acute lymphoblastic leukemia: implications for monitoring minimal residual disease

Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL.     

Viral dynamics and their relations to baseline factors and longer term virologic responses in treatment-naive HIV-1-infected patients receiving abacavir in combination with HIV-1 protease inhibitors

From a study of 71 HIV-1-infected patients receiving abacavir in combination with 1 of 5 different HIV-1 protease inhibitors (indinavir, ritonavir, saquinavir, nelfinavir, or amprenavir), we found that the baseline HIV-1 RNA levels were highly predictive of the viral decay rates. The baseline HIV-1 RNA levels were negatively correlated with the first phase viral decay rates (r = -0.77, P < 0.001) and positively correlated with the second phase viral decay rates (r = 0.68, P < 0.001). In addition, the first phase viral decay rate was positively correlated with CD4+ cell increases. No significant correlation was found between viral decay rates and longer term (24 weeks) virologic responses, and no difference in viral decay rates was found among the 5 study regimens. These data suggest that the potency of the 5 treatment regimens was similar and was not predictive of long-term virologic failure.     

Natural cytotoxic autoantibody against thymocytes in NZB mice

NZB mice were found to produce natural thymocytotoxic autoantibody in high prevalence and antibody titre. This autoantibody in NZB mice was detectable by the cytotoxicity test at both 4°C and 37°C; the prevalence and antibody titre were generally higher at 4°C. Mice of other strains also produced natural thymocytotoxic autoantibody although in lower prevalence and antibody titre and in some instances the activity was greater at 37°C than at 4°C. Natural thymocytotoxic autoantibody in NZB mice reacted equally with the thymocytes of virtually all strains of mice tested but to a lesser degree with the thymocytes of SJL/J mice. A serum pool obtained from old NZB mice had an extremely high titre of natural thymocytotoxic autoantibody (1:1024 at 4°C). Nevertheless, the cells in lymph nodes, spleen and blood leucocytes were only partially sensitive to this serum pool, and bone marrow cells were for the most part negative. By absorption, the antigen reacting with natural thymocytotoxic autoantibody was found in thymus, lymph node, spleen and brain of adult mice, thymus of newborn mice and some leukaemias. Natural thymocytotoxic autoantibody in NZB mice was an IgM-globulin as determined by sensitivity to 2-mercaptoethanol treatment and by Sephadex G-200 column chromatography in contrast to other natural antibodies (antinuclear, antierythrocyte and G antibodies) of IgG-globulin class. NZB mice also produced natural antibodies against thymocytes of the rat and the hamster; these antibodies were species-specific and did not react with the thymocytes of any but the homologous species.     

Births of normal daughters after MicroSort sperm separation and intrauterine insemination, in-vitro fertilization, or intracytoplasmic sperm injection

The world's first deliveries of normal babies after use of flow cytometric separated human sperm cells (MicroSort) for preconception gender selection are reported. Offspring were of the desired female gender in 92.9% of the pregnancies. Most of these pregnancies and births were achieved after simple intrauterine insemination.      

Detecting pre-ovulatory luteinizing hormone surges in urine

The study objectives were to determine (i) if pre-ovulatory luteinizing hormone (LH) surges, undetected in urine by two immunoradiometric assays (IRMA), were detectable by an ultrasensitive immunofluorometric assay (IFMA) and (ii) the influence of creatinine adjustment on the detection and timing of the urinary LH surges. Daily urine specimens were contributed by healthy 25-36 year old volunteers during 14 ovulatory menstrual cycles for an epidemiological study conducted in 1983-1985. Specimens were selected as having been previously assayed by two IRMA without consistently detecting LH surges. These urine specimens were remeasured using an IFMA and adjusted for creatinine concentration. IFMA measurements revealed unambiguous LH surges in all cycles. Adjusting IRMA urinary LH values for creatinine concentrations revealed previously undetected LH surges in four of eight cycles. Creatinine adjustment also altered the timing of IRMA and IFMA LH surges by 1-5 days. These results demonstrate an IFMA that detects pre- ovulatory LH surges in unpreserved, frozen urine from cycles where such surges were previously undetectable. Further, creatinine adjustment can markedly affect detection and timing of the onset and peak of the urinary LH surge. While our analysis suggests that this adjustment improves the validity of the LH measure, this requires further investigation.      

Changes in lymphoid populations of ageing CBA and NZB mice

Changes in subpopulations of lymphoid cells of normal (CBA) and autoimmune (NZB) mice were studied as a function of age, by observing migration patterns of ⁵¹Cr labelled lymph node, spleen and thymus cells from donors aged 8 days to 12 months. The method permits analysis of the proportions and numbers of recirculating and non-recirculating lymphocytes in lymphoid compartments. Changes in the lymphoid populations of CBA mice were found, which could be attributed to the normal processes of maturation and senescence. In NZB mice relative and absolute decreases in the recirculating cell content of lymph node and spleen were observed which coincided with the time of development of autoimmunity. The significance of these results, in relation to altered immunocompetence with age, is discussed.     

A simple index to identify occult bacterial infection in adults with acute unexplained fever

Patients with acute fever (less than three weeks' duration) and no localizing symptoms or physical findings to suggest a source (unexplained fever) may have self-limited illness or occult bacterial infection requiring prompt treatment. To develop a management strategy for patients with unexplained fever, we studied 880 adults who were evaluated for acute fever in an emergency room. At presentation, 135 (15%) patients had unexplained fever. Occult bacterial infection was found in 48 (35%) of these 135 patients, and 21 (44%) of 48 infected patients had bacteremia. Four bacteremic patients were incorrectly discharged from the emergency room without antimicrobial therapy. Neither a "toxic" appearance of the patient nor an initial temperature of greater than or equal to 39.4 degrees C (103 degrees F) were predictive of occult bacterial infection. An index of predictive features was developed that included: age 50 years or older; diabetes mellitus; a white blood cell count greater than or equal to 15,000/mm3 (15 X 10(9)/L); a neutrophil band cell count greater than or equal to 1500/mm3 (1.5 X 10(9)/L); and a Wintrobe erythrocyte sedimentation rate greater than or equal to 30 mm/h. In patients with 0, 1, 2, or 3 or more index features present, the proportions having occult bacterial infection were 5% (1/21), 33% (15/45), 39% (15/38), and 55% (17/31), respectively. All four bacteremic patients incorrectly discharged had two or more of the index features. Adults presenting with acute unexplained fever often have life-threatening bacterial infection. A simple clinical index can be used to estimate the likelihood of occult infection and may reduce the frequency of diagnostic error.     

Report from Capetown: GNP+ and ICW hold annual meetings

Capetown, South Africa, has recently hosted the Third Annual Gathering of the International Community of Women Living with HIV/AIDS (ICW) and the Seventh Annual International Conference of the Global Network of People Living with HIV/AIDS (GNP+). The National Council for International Health's AIDS Program sent two participants to the conferences: ICW's key contact in the Caribbean, who is from Trinidad and Tobago, and a US activist from the AIDS Project, Los Angeles. About 200 women from 70 countries attended the ICW conference. Topics included overcoming isolation, caring for others and themselves, sexual abuse, harassment and violence against women, loss/bereavement, situation of women in Africa and the impact of HIV, sexual health, treatments, access to medical care, pregnancy and motherhood, and the impact of HIV on children. More than 400 persons attended the GNP+ conference. The major program tracks were the dichotomy between the importance of holistic health strategies in many parts of the developing world and treatment of opportunistic infections and antiviral treatment in the developed world, travel restrictions, skills building, and communication. Priorities identified during the business sessions were expansion of the network's communication capabilities and enhancement of the autonomy of each of the regions. The GNP+ conference was a significant opportunity for South African PWAs (persons with AIDS) to meet people from around the world. The South African Ministry of Health is committed to a national PWA conference and an affirmative action plan to include more HIV-seropositive staff members in the National AIDS Control Program and the Ministry. Ongoing activities of ICW and GNP+ are preparation of proposals for support from major donors and planning a global survey of the living conditions of persons living with HIV/AIDS and another survey focusing on human rights.