Bone mineral content of two populations of Chinese children with different calcium intakes

Bone mineral content (BMC) of 5-year-old Chinese children (115 children in Jiangmen, China and 128 children in Hong Kong) was evaluated by single-photon absorptiometry at the distal 1/3 radius. The mean (S.D.) calcium intakes of children of Jiangmen and Hong Kong were 244 (46) and 542 (332) mg/day, respectively. The mean BMC, weight and height of Jiangmen children were significantly less than Hong Kong children by 14%, 10% and 4%, respectively (P < 0.001). Multiple regression analysis showed that 62% of the variance in BMC was explained by bone width (BW), weight and regional location (P < 0.0001). A regional difference in BMC of 0.0303 g/cm (P < 0.0001) still remained after adjusting for BW and weight by multiple regression analysis. When comparing sub-groups of children in the two regions with comparable low current calcium intake at 5 years, the BMC of Jiangmen children was still significantly lower than Hong Kong children even when potential confounders were adjusted (P < 0.003). The study suggests that the regional discrepancy in BMC might be explained by long-term habitual calcium intake and physical activity.

Spinal projections of pelvic visceral afferents of the rat: a calcitonin gene-related peptide (CGRP) immunohistochemical study

Little information is available concerning the pelvic visceral afferent system, in view of its terminal location in the spinal cord and its associated transmitter substances in the rat. By utilizing an immunostaining method to examine the transneuronal neurotransmitter depletion resulting from peripheral sensory nerve injury, the spinal projections of primary afferent fibers containing calcitonin gene-related peptide (CGRP) and originating from pelvic viscera were studied in the lumbosacral spinal cord of the rat. After unilateral or bilateral pelvic nerve section, CGRP immunoreactivity in the lumbosacral spinal cord was decreased greatly in the sacral parasympathetic nucleus (SPN), the dorsolateral fasiculus, the medial border of the dorsal horn, the dorsal gray commissure (DGC), and the intermediate gray connecting the SPN and DGC. Fine structural analysis showed that the CGRP-immunoreactive terminals made synaptic contact with dendrites and, rarely, with somata. Although there was some incidence of a synaptic contact between a CGRP-IR terminal and a vesicle-containing profile, definite evidence of axo-axonal synapse has not been confirmed. These data indicate that CGRP-containing pelvic visceral primary afferent fibers project to autonomic areas of the lumbosacral spinal cord by way of the pelvic nerve and make synaptic contact with dendrites and somata.

Relationship between long-term calcium intake and bone mineral content of children aged from birth to 5 years

This study evaluated Ca intake in Hong Kong Chinese children and examined the association between long-term Ca intake and bone mineral content (BMC) in children. Longitudinal dietary intake from birth to 5 years was obtained in 128 children (sixty-seven boys, sixty-one girls). Ca intakes were evaluated by dietary history and cross-checked with food frequency and 24 h recall. At age 5 years BMC was determined at the one-third distal radius of the right arm using single-photon absorptiometry. The mean Ca intake of 133 children at 5 years was 546 (SD 325) mg/d. Milk was the chief source of Ca (43.5%). From birth to 5 years, 90% of the children had been taking milk regularly. The mean BMC and bone width (BW) of these children were 0.317 (SD 0.042) g/cm and 0.756 (SD 0.074) cm respectively. BMC was not correlated with current intakes of Ca, energy and protein but was positively correlated with weight (r 0.57), height (r 0.47) and BW (r 0.66). However, cumulative Ca intake throughout the past 5 years showed significant correlation with BMC (r 0.235, P = 0.0133). The significant correlation remained even after weight, height, BW, sex, and cumulative intakes of energy and protein were adjusted in multiple regression analysis (r 0.248, P = 0.0107). Moreover, using principal component analysis, Ca intake during the 2nd year of life had the strongest correlation with BMC at 5 years (r 0.240, P = 0.02). Ca intake of Hong Kong Chinese children was higher than the RDA of the Food and Agriculture Organization/World Health Organization (1962) and achieved 66% of the current US recommendation (National Research Council, 1989). The increased regular milk consumption reflects a significant change in dietary habits of the younger generation. Children with a habitually higher Ca intake throughout the past 5 years, particularly in the 2nd year, were found to have higher BMC.

Specificity of disease induced by M-MuLV chimeric retroviruses containing v-myc or v-src is not determined by the LTR

The long terminal repeats (LTRs) of defective Moloney Murine Leukemia Virus (M-MuLV) containing the avian v-myc and v-src oncogenes were exchanged for LTRs from murine retroviruses inducing myeloid and erythroid disease, in an attempt to retarget disease specificity. Chimeric MuLVs containing either the Myeloproliferative sarcoma virus or the Rauscher mink cell focus-inducing virus LTRs induced the same disease as the parental viruses, suggesting that for these viruses the v-myc and v-src oncogenes are the major determinants in the disease specificity. However, substitution of the LTRs did affect the efficiency of tumorigenesis.

Delayed-onset intraventricular hemorrhage in a full-term neonate: report of one case

Intraventricular hemorrhage (IVH) in the full-term neonates is not as common as in the premature neonates. We describes a full-term neonate who presented with delayed onset of intraventricular hemorrhage and fever. Her perinatal and delivery course were uncomplicated. Clinically, omphalitis was found on admission. However, no definite etiology of IVH was discovered. Follow-up brain sonography at the age of seven months revealed complete resolution of IVH. The prognosis of the patient was good on follow-up, which was comparable with other reports.

Cross-reactive lysis of human targets infected with prototypic and clinical human immunodeficiency virus type 1 (HIV-1) strains by murine anti-HIV-1 IIIB env-specific cytotoxic T lymphocytes

To evaluate the ability of murine anti-human immunodeficiency virus type 1 (HIV-1) IIIB env cytotoxic T lymphocytes (CTL) to recognize and lyse HIV-1-infected cells, we have constructed a human cell line (Hu/Dd) expressing both the CD4 receptor and the murine H-2Dd major histocompatibility complex (MHC) class I protein. This cell line can be productively infected with HIV-1 and can also function as a target for murine CD8+, class I MHC-restricted CTL directed against the envelope glycoprotein of HIV-1 IIIB. The ability of BALB/c anti-HIV-1 IIIB env CTL to specifically recognize and lyse Hu/Dd target cells infected with divergent HIV-1 strains was tested by using both prototypic and clinical HIV-1 strains. CTL generated by immunization of mice with syngeneic cells expressing either the native or V3 loop-deleted (delta V3) envelope glycoprotein from HIV-1 IIIB were able to recognize and specifically lyse Hu/Dd target cells infected with the HIV-1 prototypic isolates IIIB, MN, WMJ II, SF2, and CC as well as several HIV-1 clinical isolates. These results demonstrate that CTL determinants for HIV-1 env exist outside the hypervariable V3 region, anti-HIV-1 IIIB env CTL appear to recognize common determinants on diverse HIV-1 strains, and classification of HIV-1 strains based on neutralizing antibody reactivities does not appear to correspond to CTL recognition and lysis. The results suggest that the cell-mediated components of the immune system may have a broader recognition of divergent HIV-1 strains than do the humoral components.

Fungal peritonitis in continuous ambulatory peritoneal dialysis--the Auckland experience

Fungal infection is an uncommon cause of peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD). We report our center's experience with 38 episodes of fungal peritonitis occurring in 33 patients, out of a total of 503 patients managed on CAPD over 11 1/2 years, and review the relevant literature. Our usual management philosophy has been one of early peritoneal catheter removal without antifungal therapy. In those with worsening clinical features, and in those with persistence of signs and symptoms beyond 48 hours after catheter removal, antifungal drugs were administered. Only five patients received antifungal therapy initially, followed by later catheter removal. Seventy-six percent of patients treated by catheter removal alone (N = 21) and 64% of patients treated by catheter removal followed by antifungal therapy (N = 11) were successfully reestablished on CAPD. A policy of early catheter removal, usually alone, but followed by antifungal therapy in select cases, can be associated with a mortality rate of less than 15% and a high rate of return to effective peritoneal dialysis.

Memory T cells are anergic to the superantigen staphylococcal enterotoxin B

We have used staphylococcal enterotoxin B (SEB) to study the role of naive and memory T cells in the induction of peripheral tolerance. After administration of SEB to mice, the numbers of naive and memory T cells increase, as does the proportion of memory T cells, which are unresponsive to further stimulation with SEB in vitro. In addition, memory T cells generated in response to conventional antigen, which proliferate and provide help to B cells in the presence of the conventional antigen, fail to respond to superantigen. Hence, memory T cells, in general, are anergized by SEB. These results suggest that SEB-induced activation and anergy reflect the combined responses of naive and memory T cells. The differential activation vs. anergy of naive and memory T cells by superantigen may be related to cytokine production and may play an important role in the etiology of autoimmune diseases or immunodeficiency diseases such as acquired immune deficiency syndrome.

Polymerase chain reaction in detection of CMV DNA in renal allograft recipients

This study investigates the use of polymerase chain reaction (PCR) in comparison with viral culture and serology for monitoring of cytomegalovirus (CMV) infection in 21 consecutive renal allograft recipients treated with a quadruple immunosuppression protocol. In addition, an attempt is made to explore the significance of quantitation of CMV signals obtained from peripheral blood leucocytes. CMV infection developed in 16 patients with seven of these patients having organ involvement. All of these 16 patients had a fourfold rise in antibody titres as well as positive identification of CMV DNA in peripheral blood leucocytes by PCR. Blood viral cultures were negative in two of these patients. All five patients who remained PCR negative also remained culture negative with no antibody change. PCR detected CMV infection on average 15 days and 20 days earlier than viral culture and serology respectively. All except one of the patients with CMV organ involvement had an initial peak of CMV DNA followed by prolonged carriage of detectable CMV. The majority of patients with fever only or asymptomatic CMV infection had a transient peak of CMV DNA. A high incidence of CMV disease with organ involvement occurred in seronegative recipients of kidneys from seropositive donors (3/5) and in seropositive recipients of kidneys from seronegative donors (3/7). OKT3 was associated with a higher incidence of CMV organ involvement compared to Antilymphocytic globulin (3/5 v 4/16) but there was a higher incidence of CMV mismatched patients in the OKT3 treated group.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in expression of CD45R during the development of Th1 and Th2 cell lines

Previous studies using anti-CD45R monoclonal antibodies (mAb) have shown that normal CD4+ T cells can be separated into virgin and memory cells based on their level of expression of CD45R. CD45Rhi (virgin) T cells secrete interleukin (IL)-2 whereas CD45Rlo (memory) T cells secrete both IL-2 and IL-4. In contrast to these results, studies using cultured T cell lines have shown that IL-2-secreting T helper cell type 1 (Th1) cells are CD45Rlo and IL-4-secreting Th2 cells are CD45Rhi. To resolve this discrepancy, and to determine how the Th1 and Th2 cell lines relate to memory CD45Rlo and virgin CD45Rhi CD4+ T cells, we have isolated CD45Rlo cells from alloantigen-primed mice and developed allospecific Th1 and Th2 cell lines. The lymphokines secreted by these lines were then evaluated. Our results show that as CD45Rlo T cells develop into in vitro cell lines which secrete IL-4, they become CD45Rhi. In contrast, CD45Rlo cells that develop into lines which secrete IL-2 maintain their CD45Rlo phenotype. Thus, although both Th1 and Th2 cells arise initially from CD45Rlo cells, Th2 cells become CD45Rhi during prolonged in vitro culture but, Th1 cells do not.

Lysine-21 of Leuconostoc mesenteroides glucose 6-phosphate dehydrogenase participates in substrate binding through charge-charge interaction

Leuconostoc mesenteroides glucose 6-phosphate dehydrogenase (G6PD) was isolated in high yield and purified to homogeneity from a newly constructed strain of Escherichia coli which lacks its own glucose 6-phosphate dehydrogenase gene. Lys-21 is one of two lysyl residues in the enzyme previously modified by the affinity labels pyridoxal 5'-phosphate and pyridoxal 5'-diphosphate-5'-adenosine, which are competitive inhibitors of the enzyme with respect to glucose 6-phosphate (LaDine, J.R., Carlow, D., Lee, W.T., Cross, R.L., Flynn, T.G., & Levy, H.R., 1991, J. Biol. Chem. 266, 5558-5562). K21R and K21Q mutants of the enzyme were purified to homogeneity and characterized kinetically to determine the function of Lys-21. Both mutant enzymes showed increased Km-values for glucose 6-phosphate compared to wild-type enzyme: 1.4-fold (NAD-linked reaction) and 2.1-fold (NADP-linked reaction) for the K21R enzyme, and 36-fold (NAD-linked reaction) and 53-fold (NADP-linked reaction) for the K21Q enzyme. The Km for NADP+ was unchanged in both mutant enzymes. The Km for NAD+ was increased 1.5- and 3.2-fold, compared to the wild-type enzyme, in the K21R and K21Q enzymes, respectively. For the K21R enzyme the kcat for the NAD- and NADP-linked reactions was unchanged. The kcat for the K21Q enzyme was increased in the NAD-linked reaction by 26% and decreased by 30% in the NADP-linked reaction from the values for the wild-type enzyme. The data are consistent with Lys-21 participating in the binding of the phosphate group of the substrate to the enzyme via charge-charge interaction.

Changes in expression of J11d on murine B cells during activation and generation of memory

J11d is an antigen expressed on a variety of hemopoietic cells including B cells. In this report we describe the expression of J11d on functional subpopulations of B cells from adult mice of different ages or at different stages of an immune response. In addition we explore the relationship between the expression of J11d and that of other markers characteristic of memory B cells. Our results show that expression of J11d on B cells is related to the immunologic history of the host. Thus, J11d on B cells from normal mice is decreased as the mice age and are thereby exposed to environmental antigens. Down-regulation of J11d on B cells does not occur in germfree or nude mice but does occur when nude mice are reconstituted with T cells and/or are immunized. Since B cells expressing low levels of J11d accumulate following exposure to antigens, we also determined whether memory cells reside in the J11dlo cell population. To this end, we studied primed mice and found that expression of J11d on antigen-specific B cells increased during the first week after immunization and decreased thereafter. Increases in expression of J11d after activation also occurred in B cells stimulated with lipopolysaccharide (LPS) in vitro. However, antigen-specific B cells from long-term primed mice which expressed lower levels of J11d and antigen-specific receptors of higher affinity also expressed lower densities of sIgM and included most sIgG+ cells. Furthermore, these antigen-specific J11dlo B cells transferred a memory response, whereas J11dhi cells did not. Taken together, these data indicate that the level of expression of J11d on B cells distinguishes virgin (J11dhi) from memory (J11dlo) cells in mice.

Virgin T cells do not provide help for antigen-specific B cells in the absence of IL-4, IL-5, and IL-6

We have used a mAb, 23G2, directed against the B exon of the murine CD45 molecule to identify and separate two subpopulations of normal peripheral CD4+ T cells. Examination of these two subpopulations indicates that they correspond to virgin (TV) (CD45RBhi) and memory (Tm) (CD45RBlo) cells. In this report we have determined the abilities of TV and Tm cells to provide antigen-specific, cognate help to hapten-specific antigen-binding B cells. To this end we have enriched Tv and Tm cell populations from splenic CD4+ T cells and have cultured these cells with TNP-specific antigen-binding cells (TNP-ABCs) and specific antigen. We then examined the ability of Tv and Tm cells to promote Ig secretion by the B cells. Both Tm and Tv cells interact with antigen-presenting B cells as assessed by proliferation and lymphokine secretion. However, Tm, but not Tv, cells promote substantial Ig secretion by TNP-ABCs in the presence of antigen. When either IL-6 or IL-4 plus IL-5 are added to cultures of Tc cells, B cells and antigen, Ig secretion is restored. Thus, Tv cells interact effectively with B cells to induce an activation signal, but in the absence of IL-4 plus IL-5 or IL-6 lymphokines, which are not secreted by Tv cells, these cells do not provide help for an antibody response. Hence, naive, peripheral Tv cells must undergo an antigen-dependent differentiation step into Tm and secrete IL-4, IL-5, and IL-6 before they can induce B cells to secrete antibody.

Free-floating ball thrombus in left atrium: pathological features and clinical implications

A patient with a free-floating ball thrombus in the left atrium complicating mitral stenosis is described. The pathological features and clinical implications are discussed.

Cloning of the gene and amino acid sequence for glucose 6-phosphate dehydrogenase from Leuconostoc mesenteroides

Amino acid sequencing of glucose 6-phosphate dehydrogenase (Glc6PD) from Leuconostoc mesenteroides yielded sequence for over 75% of the protein. Two oligonucleotides based on the amino acid sequence were used to isolate a partial Glc6PD gene clone (pLmz delta N65), from a pUC9 library, containing 85% of the coding sequence and the 3'-untranslated DNA, but lacking the 5'-noncoding DNA sequence and the portion of the gene encoding the 65 N-terminal amino acids. Attempts to obtain a full-length clone from lambda libraries were unsuccessful, possibly due to restriction of L. mesenteroides DNA by Escherichia coli host cells. The 5'-untranslated DNA was amplified by the polymerase chain reaction and partially sequenced. To obtain unmodified DNA for the gene, oligonucleotides corresponding to the 5'- and 3'-noncoding sequences were used to amplify the gene by the polymerase chain reaction, and a 1.8-kilobase pair fragment was isolated and cloned into pUC19. The recombinant plasmid, pLmz, contains the entire Glc6PD gene and expresses the gene in E. coli. pLmz was sequenced showing that the enzyme consists of 485 amino acids. L. mesenteroides Glc6PD is 31% identical to the human enzyme.

Memory B and T cells

Three remarkable and unique features of the immune system are specificity, diversity, and memory. Immunological memory involves both T and B cells and results in a secondary antibody response that is faster, of higher affinity, and results in the secretion of non-IgM isotypes of Ig. In this review we discuss the properties of memory T and B cells, their specific receptors, and the events which occur both in the nucleus and on the cell surface during generation and activation of these cells. Although memory T and B cells use different mechanisms to elaborate memory, there are a number of interesting analogies: lymphokines vs antibodies and affinity maturation of B cell antigen receptors vs upregulation of adhesion molecules on T cells. Finally, we discuss the importance of these cells in health and disease and suggest what impact additional information about these cells might have on the manipulation of the immune response.

Interaction of Leuconostoc mesenteroides glucose-6-phosphate dehydrogenase with pyridoxal 5'-diphospho-5'-adenosine. Affinity labeling of Lys-21 and Lys-343

Pyridoxal 5'-diphospho-5'-adenosine (PLP-AMP) inhibits glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides competitively with respect to glucose 6-phosphate and noncompetitively with respect to NAD+ or NADP+, with Ki = 40 microM in the NADP-linked and 34 microM in the NAD-linked reaction. Incubation of glucose-6-phosphate dehydrogenase with [3H]PLP-AMP followed by borohydride reduction shows that incorporation of 0.85 mol of PLP-AMP per mol of enzyme subunit is required for complete inactivation. Both glucose 6-phosphate and NAD+ protect against this covalent modification. The proteolysis of the modified enzyme and isolation and sequencing of the labeled peptides revealed that Lys-21 and Lys-343 are the sites of PLP-AMP interaction and that glucose 6-phosphate and NAD+ protect both lysyl residues against modification. Pyridoxal 5'-phosphate (PLP) also modifies Lys-21 and probably Lys-343. Lys-21 is part of a highly conserved region that is present in all glucose-6-phosphate dehydrogenases that have been sequenced. Lys-343 corresponds to an arginyl residue in other glucose-6-phosphate dehydrogenases and is in a region that is less homologous with those enzymes. PLP-AMP and PLP are believed to interact with L. mesenteroides glucose-6-phosphate dehydrogenase at the glucose 6-phosphate binding site. Simultaneous binding of NAD+ induces conformational changes (Kurlandsky, S. B., Hilburger, A. C., and Levy, H. R. (1988) Arch. Biochem. Biophys. 264, 93-102) that are postulated to interfere with Schiff's-base formation with PLP or PLP-AMP. One or both of the lysyl residues covalently modified by PLP or PLP-AMP may be located in regions of the enzyme undergoing the NAD(+)-induced conformational changes.

Echocardiographic diagnosis of an aortic root abscess after Mycobacterium fortuitum prosthetic valve endocarditis

A patient with an aortic root abscess complicating Mycobacterium fortuitum prosthetic endocarditis is described. The correct diagnosis had been made preoperatively by echocardiography and was confirmed subsequently at surgery.

The differential expression of homing and adhesion molecules on virgin and memory T cells in the mouse

We have used an anti-CD45R mAb to identify virgin and memory CD4+ T cells. In this report, we demonstrate that in mice, as in humans, virgin and memory T cells express different levels of adhesion molecules. Splenic CD45Rlo memory T cells express higher levels of PgP-1, Lyt-1, and LFA-1 than do CD45Rhi virgin cells. In contrast, CD45Rlo memory cells express lower levels of antigens identified by the mAbs. Mel-14 (leukocyte homing receptor) and SM3G11. These observations are in agreement with work in humans and rats which suggests that differences in the levels of adhesion molecules and homing receptors might be related to the efficiency of activation and patterns of recirculation among virgin and memory T cells.

Limiting dilution analysis of CD45Rhi and CD45Rlo T cells: further evidence that CD45Rlo cells are memory cells

Murine CD4+ T cells can be separated into two distinct populations on the basis of their levels of expression of the CD45RB antigen (CD45Rhi and CD45Rlo). Murine CD45Rlo cells arise from CD45Rhi cells after antigenic exposure and provide antigen-specific help to B cells in a secondary immune response. In the present study, the ability of CD45Rhi and CD45Rlo cells to proliferate in response to either soluble antigen or allogeneic cells was examined by limiting dilution analysis. CD45Rhi cells were the major responding cells in unprimed animals; priming caused a large increase in the frequencies of responding CD45Rlo cells and this increase was evident 11 months later. These results further support the notion that CD4+ CD45Rlo cells are long-term memory cells.

Anticoagulation instability with life-threatening complication after dietary modification

Anticoagulation instability due to a change in intake of vitamin K after dietary modification was observed in 2 patients on long-term oral anticoagulants. One patient developed diffuse bruises treated conservatively with fresh frozen plasma transfusion and the other had a thrombosed aortic prosthesis which required emergency operation. To prevent such complications, dietary modification especially with food rich in vitamin K should be undertaken with care in patients on long-term oral anticoagulants.

An arterial duct associated with a congenital anomaly of the coronary arteries: persistence of a murmur after ligation of the duct

A patient is described in whom a persistent murmur was detected after surgical ligation of an arterial duct. Subsequently, she underwent investigation and was found to have associated rare congenital anomalies of a coronary arterial fistula and a single coronary artery.

Functional and ontogenetic analysis of murine CD45Rhi and CD45Rlo CD4+ T cells

CD4+ murine T cell clones, TH1 and TH2, can be distinguished by both functional responses and by their patterns of lymphokine secretion. Recently, a mAb, 23G2, which reacts with a subset of CD45 molecules (CD45R), has been reported to bind differentially to clones of TH1 and TH2 cells. In the present study, normal splenic T cells were analyzed for differences in 23G2-reactivity and were separated into two populations based on their density of CD45R (CD45Rhi and CD45Rlo). The CD45Rhi cells secrete more IL-2 than IL-4 after stimulation in vitro; the reverse is true for the CD45Rlo cells. Because neither population secretes only IL-2 or IL-4, we were unable to classify cells as TH1 or TH2. In vivo and in vitro analyses of the CD45Rhi and CD45Rlo cells suggest a lineage relationship between the two subsets that correlates with the degree of Ag exposure and the state of maturation of the mice. In newborn mice and mice raised under sterile conditions, splenic CD4+ T cells are predominantly CD45Rhi. Under conditions of increased antigenic exposure and maturation of the mice, CD45Rlo cells develop; after long term priming in vivo, the majority of specific Ag-reactive cells are CD45Rlo. Adoptive transfer studies using BALB/c nu/nu recipients demonstrate that CD45Rhi cells become CD45Rlo cells and that the recall response (IgG) to specific Ag is mediated by CD45Rlo cells. Taken together, these data indicate that the level of expression of CD45R on CD4+ T cells distinguishes virgin (CD45Rhi) from primed/memory (CD45Rlo) T cells in normal mice.