[Human rotavirus infection in perinatal transmission]

OBJECTIVE

To investigate the perinatal infection of human rotavirus (HRV) in pregnant women and the effect on their neonates.

METHODS

HRV was examined by RT-PCR in cervical secretion and feces of 250 pregnant women and fecal samples of their neonates on the third postpartum day.

RESULTS

In pregnant women the HRV prevalence was 26.0% in feces and 8.8% in cervical secration, respectively. The infection rate of the 250 neonates in the first three days after birth was 4.4%, 15.6% and 22.0%, respectively. The HRV infection rate in neonates of infected mothers was 52.31%.

CONCLUSION

The infected mothers may be an important source for HRV infection of neonates. HRV transmitted via the labor tract and intrahospital transmission were the main sources for the neonatal infection.

[Characteristic mass and atomization efficiency of graphite furnace atomic absorption spectrometry]

Measurements of peak height and peak area characteristic masses and atomization efficiency for 7 elements (Ag, Bi, Cd, Cr, Ga, Ge and In) have been studied. The m0(i)(exp) values are compared with theoretical data, m0(i)(cal), to assess the effect of temperature on the correction factor of theorization for characteristic mass value (alpha = m0(i)(cal) m0(i)(exp)), the peak height and the peak area atomization efficiencies (betap and betai). The peak area atomization efficiency (betai) was equal to the correction factor of theorization for characteristic mass value (alpha) times tauD/tauR value. The tauR was value experimentally measured of atomic residence time and the tauD value calculated from rD = l2/8D. The betai value of elements always are smaller than the alpha values because the tauD/tauR values is less than one for most elements in the operating conditions. Past of the analyte vapours is readsorbed by the heated tube wall at high temperature and reevaporation of the adsorbed analyte followed by diffusion account for the larger atomic residence time and it appeared that the tauR value was larger than the tauD in graphite furnace.

Identification of a flexible loop region (297-313) of urokinase-type plasminogen activator, which helps determine its catalytic activity

Pro-urokinase has a much higher intrinsic catalytic activity than other zymogens of the serine protease family. Lys300(c143) in an apparent "flexible loop" region (297-313) was previously shown to be an important determinant of this intrinsic catalytic activity. This was related to the loop allowing the positive charge of Lys300(c143) to transiently interact with Asp355(c194), thereby inducing an active conformation of the protease domain (Liu, J. N., Tang, W., Sun, Z., Kung, W., Pannell, R., Sarmientos, P., and Gurewich, V. (1996) Biochemistry 35, 14070-14076). To further test this hypothesis, the charge at position 300(c143) and the flexibility of the loop were altered using site-directed mutagenesis designed according to a computer model to affect the interaction between Lys300(c143) and Asp355(c194). When the charge at Lys300(c143) but not Lys313(c156) was reduced, a significant reduction in the intrinsic catalytic activity occurred. Similarly, when the flexibility (wobbliness) of the loop was enhanced reducing the size of side chain, the intrinsic catalytic activity was also reduced. By contrast, when the loop was made less flexible, the intrinsic catalytic activity was increased. These findings were consistent with the hypothesis. The effects of these mutations on two-chain activity were less and often discordant with the intrinsic catalytic activity, indicating that they can be modulated independently. This structure-function disparity can be exploited to create a more zymogenic pro-urokinase (lower intrinsic catalytic activity) with a high catalytic activity, as exemplified by two of the mutants. The changes in intrinsic catalytic activity and two-chain activity induced by the mutations were due to changes in kcat rather than Km. Some significant structure-function differences between pro-urokinase and its highly homologous counterpart, tissue plasminogen activator, were also found.

In vitro characterization of the novel proprotein convertase PC7

Biochemical and enzymatic characterization of the novel proprotein convertase rat PC7 (rPC7) was carried out using vaccinia virus recombinants overexpressed in mammalian BSC40 cells. Pro-PC7 is synthesized as a glycosylated zymogen (101 kDa) and processed into mature rPC7 (89 kDa) in the endoplasmic reticulum. No endogenously produced soluble forms of this membrane-anchored protein were detected. A deletion mutant (65 kDa), truncated well beyond the expected C-terminal boundary of the P-domain, produced soluble rPC7 in the culture medium. Enzymatic activity assays of rPC7 using fluorogenic peptidyl substrates indicated that the pH optimum, Ca2+ dependence, and cleavage specificity of this enzyme are largely similar to those of furin. However, with some substrates, cleavage specificity more closely resembled that of yeast kexin, suggesting differential processing of proprotein substrates by this novel convertase. We examined the rPC7- and human furin-mediated cleavage of synthetic peptides containing the processing sites of three proteins known to colocalize in situ with rPC7. Whereas both enzymes correctly processed the pro-parathyroid hormone tridecapeptide and the pro-PC4 heptadecapeptide, neither enzyme cleaved a pro-epidermal growth factor hexadecapeptide. Thus, this study establishes that rPC7 is an enzymatically functional subtilisin/kexin-like serine proteinase with a cleavage specificity resembling that of hfurin. In addition, we have demonstrated that rPC7 can correctly process peptide precursors that contain the processing sites of at least two potential physiological substrates.

[Determination of atomization efficiency in graphite furnace with V-boat]

Based on that the absorbance is proportional to the effective length of the absorbing layer of atoms, a simple foumula is derived by which the atomization efficiency. Two atomization efficiencies were calculated: beta1 and beta2, which gave the fraction of calculated the total number of analytical atoms that enter the analysis volume during each stage of atomization. It is based on two different calculated ways for the mean residence time of atoms, and the beta1 and beta2 values of Ga and Tl in furnace with V-boat in various atomization temperatures were determined. Influence of the loss process of atomic vapor on the atomization efficiency value was discussed.

gamma-Interferon-induced resistance to 1,25-(OH)2 D3 in human monocytes and macrophages: a mechanism for the hypercalcemia of various granulomatoses

The hypercalcemia of various granulomatoses is caused by endogenous 1,25-dihydroxyvitamin D [1,25-(OH)2D3] overproduction by disease-activated macrophages. The inability of 1,25(OH)2D3 to suppress its synthesis in macrophages contrasts with the tight control of its production in macrophage precursors, peripheral blood monocytes (PBM). We examined whether 1,25(OH)2D3 resistance develops as PBM differentiate to macrophages or with macrophage activation. Normal human pulmonary alveolar macrophages (PAM) are less sensitive to 1,25(OH)2D3 than PBM, despite similar vitamin D receptor content; however, both PBM and PAM respond to exogenous 1,25-(OH)2D3 by inhibiting 1,25(OH)2D3 synthesis and inducing 1,25(OH)2D3 degradation through enhancement of 24-hydroxylase mRNA levels and activity. The human monocytic cell line THP-1 mimics PAM in 1,25(OH)2D3 synthesis and sensitivity to exogenous 1,25(OH)2D3. We utilized THP-1 cells to examine the response to 1,25(OH)2D3 with macrophage activation. Activation of THP-1 cells with gamma-interferon (gamma-IFN) enhances 1,25(OH)2D3 synthesis 30-fold, blocks 1,25-(OH)2D3 suppression of its synthesis, and reduces by 42.2% 1,25-(OH)2D3 induction of its degradation. The antagonistic effects of gamma-IFN are not merely restricted to enzymatic activities. In THP-1 cells and in normal PBM, gamma-IFN inhibits 1,25-(OH)2D3 induction of 24-hydroxylase mRNA levels without reducing mRNA stability, suggesting gamma-IFN inhibition of 1,25(OH)2D3 transactivating function. These results explain 1,25(OH)2D3 overproduction in granulomatoses and demonstrate potent inhibition by gamma-IFN of 1,25(OH)2D3 action in immune cells.

State-imposed limits on Medicaid reimbursement for nursing facility care

OBJECTIVES

Nursing cost-center limits were examined, along with their effects on Medicaid.

METHODS

A national survey of Medicaid nursing facility reimbursement provided data on cost centers for nursing, administration, and capital, whether in specific, larger, or multiple cost centers.

RESULTS

Most states impose nursing and administration limits. Far fewer states impose capital limits, but only capital limits may be related to constraint of reimbursement rates.

CONCLUSIONS

Shifting toward limiting capital costs, or simply eliminating cost-center limits, might accommodate cost control while removing negative constraints on direct resident care.

[The expression of proliferating cell nuclear antigen and p53 protein in salivary gland tumours]

The expressions and distributions of PCNA and p53 protein were studied with anti-PCNA and anti-p53 protein MoAbs, using immunohistochemical staining method in salivary gland tumour. The relationship between PCNA and p53 protein was also studied. Results indicated: Malignant mixed tumour (MmT) had a higher proliferating index (PI) of PCNA. The PI could be used as one of adjuvant diagnostic criteria; and as an important parameter for grading mucoepidermoid carcinoma (MEC); The positive expression of p53 might be a good tumour marker for MmT; Tumour tissues with positive expression of p53 had been shown higher PI of PCNA, however there was no significance difference in our group; It remained to be studied later.

[Human parvovirus B19 infection in perinatal transmission and abnormal fetuses]

OBJECTIVE

To investigate the perinatal infection of human parvovirus B19 in pregnant women and their fetuses.

METHODS

350 sera of normal pregnant women and 9 sera of abnormal fetuses were investigated by polymerase chain reaction (PCR) to check the parvovirus B19 DNA.

RESULTS

The prevalence of parvovirus B19 DNA was 1.14% and 0.28% in the sera of normal pregnant women and umbilical cords, respectively. Parvovirus B19 DNA was detected in 6 sera of pregnant women and umbilical cords from 9 abnormal fetuses parvovirus DNA could be detected by in situ hybridization in the nuclei of immature hematopoetic cells within fetal brain or spleen whose PCR tests were positive.

CONCLUSION

The results suggest that parvovirus B19 infection do exist in pregnant women and their neonates as well as fetuses in our country. PCR and in situ hybridization could provide more sensitive, more accurate and specific methods for clinical pathologic diagnosis and epidemic investigation.

Thermodynamics of dT--dT base pair mismatching in linear DNA duplexes and three-arm DNA junctions

We have used a combination of magnetic-suspension densimetry and calorimetry to derive complete thermodynamic profiles, including volume changes, for the formation of linear DNA duplexes and three-arm branched DNA junctions, from their component strands, with and without dT-dT mismatches. The formation of each type of complex at 20 degrees C is accompanied by a favorable free energy, with a favorable enthalpy term partially compensated by an unfavorable entropy. Formation is associated also with net uptake of water molecules. Using the formation of the fully-paired linear duplex or three-arm junction as reference states, we can establish a thermodynamic cycle in which the contribution of the single-strand species cancels. From this cycle, we determine that substitution of dA for dT has a differential free energy of deltadeltaG degrees of +2.4 kcal mol(-1) for mismatched duplex and +2.0 kcal mol(-1) (on the average) for the mismatched junction. These unfavorable differential free energies result from an unfavorable enthalpy, partially compensated by a favorable entropy, and a negative deltadeltaV. The free energies in the two cases have signs opposed to those of deltadeltaV, a situation that implicates hydration changes in creating the mismatch. When the deltadeltaV terms are normalized by the total number of base pairs involved, the immobilization of structural water molecules (and/or substitution of electrostricted for hydrophobic water molecules) is about 7 times greater for junctions than duplexes. This is consistent with more extensive hydrophobic hydration of branched DNA structures than of duplexes.

[Reasons of failure in blocking mother-infant transmission of HBV by using vaccine and related strategies]

We have detected the serum marker of HBV of 32 mothers whose HBsAg present positive and their children whom were given Hepatitis B vaccine immunization throughout duration of their mothers' pregnancy, altogether making up 66 cases. In 3 of these 32 families, Hepatitis B vaccine failed to block transmission between mother and infant. Direct nucleotide sequence analysis of HBV were carried out in 7 HBsAg positive infected persons. To confirm the possibility of HBV transmission between mother and infant on molecular level, we used PCR technique and DNA sequencing method. The reasons of which HBV vaccine failed in blocking transmission were discussed at the point of views of virus variation. Besides, we make and emphasized discussion on how to tighten up the measurement of controlling the course of infection and protecting susceptible population.

Proteolytic mapping of heat shock transcription factor domains

Heat shock transcription factors (HSFs) of higher eukaryotes respond to physical and cellular stress signals by trimerizing, binding to a specific site on DNA, and transactivating genes encoding the heat shock proteins. In this work, limited proteolysis was used as a biochemical probe of the domain organization of Drosophila HSF. Both unshocked monomeric and heat-shocked trimeric HSF possess an internal protease-sensitive region located between the amino-terminal and carboxyl-terminal hydrophobic heatad repeats, suggesting that this is a less structured region compared to those defined for DNA-binding, trimerization, and transactivation. For a few cleavage sites, the heat-shocked form of HSF is more accessible to proteases than the unshocked form, providing an additional diagnostic marker for inducible changes in conformation or modification between the latent and activated forms of HSF.

Functional analysis of human PACE4-A and PACE4-C isoforms: identification of a new PACE4-CS isoform

There are seven known subtilisin/kexin-like proprotein convertases responsible for the processing of numerous precursors at either pairs or specific single basic residues. Three members, PACE4, PC4 and PC5, exhibit alternative splicing of their RNAs resulting in the generation of multiple isoforms differing in their C- or N-terminal segments. In this study we examined the biosynthesis, functional activity and cellular localization of two of these isoforms, namely the full length PACE4-A and the C-terminally truncated PACE4-C which lacks 11 amino acids at the end of its chaperone-like P-domain. We report the existence of a new isoform, termed PACE4-CS, which is a C-terminally shortened version of PACE4-C. Cellular expression results demonstrated that PACE4-A codes for a functional secretable enzyme capable of cleaving pro7B2 into 7B2. In contrast, PACE4-CS is not secreted since it remains in the endoplasmic reticulum as an inactive zymogen form, thereby emphasizing the importance of the integrity of the P-domain. Microsequencing of the intracellular PACE4-CS protein in two cell lines revealed that it is proPACE4-CS with an N-terminal trimming reminiscent of the action of a dipeptidylpeptidase recognizing the motifs X-Ala and X-Pro.

Renal calcitriol synthesis and serum phosphorus in response to dietary phosphorus restriction and anabolic agents

Calcitriol [1,25-(OH)2D3] synthesis by the renal 25-hydroxyvitamin D3-1alpha-hydroxylase (1alpha-hydroxylase) is induced in rats on a low phosphorus diet, but not in the hypophysectomized (HPX) or diabetic rat. However, the normal response is restored by the administration of growth hormone (GH) or insulin-like growth factor-I (IGF-I), or insulin, respectively. To further characterize this in vivo phenomenon, the acute effects of GH, IGF-I, and insulin were studied in the HPX rat. In the HPX rat the low phosphorus diet alone did not significantly alter serum phosphorus or 1alpha-hydroxylase activity, but treatment with GH resulted in a marked decrease in serum phosphorus that was associated with a fivefold induction of enzyme activity. Time course studies showed that by 6 hours after GH administration, hepatic IGF-I mRNA had increased 10-fold while renal IGF-I mRNA had increased by only 52%. Between 6 and 12 hours, serum phosphorus decreased dramatically and 1alpha-hydroxylase activity increased twofold. Treatment of phosphorus-restricted HPX rats with IGF-I resulted in a decrease in serum phosphorus by 2 hours that preceded a fourfold increase in enzyme activity between 6 and 10 hours. Treatment of phosphorus-restricted HPX rats with insulin produced similar results. This is the first demonstration of hypophosphatemia preceding induction of the 1alpha-hydroxylase after administration of IGF-I or insulin to the HPX rat on a low phosphorus diet. Although these growth factors may have a direct effect on the 1alpha-hydroxylase, these data suggest that the influence of GH, IGF-I, and insulin on transcellular phosphorus flux may have an independent effect on enzyme activity. Furthermore, the much greater induction of hepatic compared with renal IGF-I mRNA in response to GH suggests that systemic, rather than the local, IGF-I may be required for induction of the 1alpha-hydroxylase. This effect may be mediated by either the insulin or the IGF-I receptor.

Expression of the renal 25-hydroxyvitamin D-24-hydroxylase gene: regulation by dietary phosphate

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] plays a key role in phosphate (Pi) homeostasis through its phosphatemic actions on intestine and bone. In turn, dietary Pi restriction increases serum 1,25(OH)2D3 by stimulating its production, but its effect on vitamin D catabolism is less clear. Here we have examined the effects of dietary Pi on the expression of the renal vitamin D-24-hydroxylase (24-OHase), the first enzyme in the catabolic pathway for vitamin D compounds. Rats fed a low Pi (0.02% P) diet showed a fivefold decrease in renal 24-OHase mRNA compared with rats fed a normal Pi (0.67% P) diet. 24-OHase mRNA and 24-OHase activity decreased within 24 h of Pi restriction, reached a minimum by 48 h, and remained low through 14 days. Decreased 24-OHase mRNA was observed with more moderate Pi restriction (0.2% P), but higher Pi (1.2% P) did not increase 24-OHase mRNA over the 0.8% P diet. 24-OHase mRNA correlated well with plasma Pi (r = 0.862, P < 0.001). In conclusion, renal 24-OHase expression is regulated by dietary phosphate at the mRNA level.

Phosphorus restriction prevents parathyroid gland growth. High phosphorus directly stimulates PTH secretion in vitro

Dietary phosphorus (P) restriction is known to ameliorate secondary hyperparathyroidism in renal failure patients. In early renal failure, this effect may be mediated by an increase in 1,25-(OH)2D3, whereas in advanced renal failure, P restriction can act independent of changes in 1,25-(OH)2D3 and serum ionized calcium (ICa). In this study, we examined the effects of dietary P on serum PTH, PTH mRNA, and parathyroid gland (PTG) hyperplasia in uremic rats. Normal and uremic rats were maintained on a low (0.2%) or high (0.8%) P diet for 2 mo. PTG weight and serum PTH were similar in both groups of normal rats and in uremic rats fed the 0.2% P diet. In contrast, there were significant increases in serum PTH (130 +/- 25 vs. 35 +/- 3.5 pg/ml, P < 0.01), PTG weight (1.80 +/- 0.13 vs. 0.88 +/- 0.06 microg/gram of body weight, P < 0.01), and PTG DNA (1.63 +/- 0.24 vs. 0.94 +/- 0.07 microg DNA/gland, P < 0.01) in the uremic rats fed the 0.8% P diet as compared with uremic rats fed the 0.2% P diet. Serum ICa and 1,25-(OH)2D3 were not altered over this range of dietary P, suggesting a direct effect of P on PTG function. We tested this possibility in organ cultures of rat PTGs. While PTH secretion was acutely (30 min) regulated by medium calcium, the effects of medium P were not evident until 3 h. During a 6-h incubation, PTH accumulation was significantly greater in the 2.8 mM P medium than in the 0.2 mM P medium (1,706 +/- 215 vs. 1,033 +/- 209 pg/microg DNA, P < 0.02); the medium ICa was 1.25 mM in both conditions. Medium P did not alter PTH mRNA in this system, but cycloheximide (10 microg/ml) abolished the effect of P on PTH secretion. Thus, the effect of P is posttranscriptional, affecting PTH at a translational or posttranslational step. Collectively, these in vivo and in vitro results demonstrate a direct action of P on PTG function that is independent of ICa and 1,25-(OH)2D3.

Evaluation of a polymerase chain reaction-based assay for diagnosis of Wuchereria bancrofti infection

To assess the utility of a polymerase chain reaction (PCR)-based method for diagnosis of Wuchereria bancrofti infection, blood, plasma, and paraffin-embedded tissue samples were tested using a PCR-based assay that detects a W. bancrofti-specific repetitive DNA sequence. The assay was positive in 100 microL of blood from 40 of 42 microfilaria-positive subjects, the 2 subjects with negative assays having microfilarial counts of 1. Samples from 127 uninfected subjects were PCR-negative. The assay was also positive in 7 of 10 daytime samples in regions where infection is nocturnally periodic; PCR amplification from paraffin-embedded sections established the diagnosis of W. bancrofti infection in another 2 cases. A microtiter ELISA plate-based method was developed for rapid evaluation of large numbers of samples. These results suggest that this PCR-based assay will be useful in diagnosis of W. bancrofti infection in a variety of clinical settings.

[Effect of IL-4 on biological regulation of tumor cell lines]

The effect of IL-4 on biological regulation of tumor cell lines was observed by using human recombinant interleukin-4. The observation included cell proliferation, differentiation, cell surface marker and cytokine secretion. The effect of IL-4 on cell proliferation of nine cell lines was different. It showed 4/9 inhibitory effect, 3/9 enhancing effect and 2/9 no effect. The inhibitory effect of IL-4 on U937 cell proliferation was correlated with cell differentiation. IL-4 enhanced the expression of cell surface markers (including MHC class I, MHC class II and TAA) of some cell lines. Furthermore, IL-4 inhibited the production of IL-2 by MLA144. The preliminary results indicate that the effect of IL-4 on biological regulation of tumor cell lines is benefitial for controlling tumor cell growth and enhancing tumor cell recognition by effector cells. However, the down regulation also could be exerted.

A polymerase chain reaction assay for detection of the parasite Wuchereria bancrofti in human blood samples

To identify Wuchereria bancrofti DNA sequences that could be used as the basis for a simple and rapid parasite detection assay, a genomic library of W. bancrofti was constructed and screened for highly repeated DNA. The repeat found with the highest copy number was 195 basepairs (bps) long, 77% AT, and 300 copies per haploid genome. This sequence was designated the Ssp I repeat because it has a unique recognition site for that restriction endonuclease in all or most of the repeat copies. The Ssp I repeat DNA family is dispersed, genus-specific, and exists in all of the different geographic isolates of W. bancrofti tested. Based on DNA sequence analysis of this repeat, we have developed an assay to detect very small quantities of W. bancrofti DNA using the polymerase chain reaction (PCR). With this PCR assay, the Ssp I repeat was detected in as little as 1 pg of w. bancrofti genomic DNA (about 1% of the DNA in one microfilaria) added to 100 microliters of human blood. The PCR assay also amplified Ssp I repeat DNA from geographic isolates of W. bancrofti from around the world but not from other species of filariae or from human or mosquito DNA. Microfilaria-positive human blood samples collected in Mauke, Cook Islands were shown to be Ssp I PCR-positive, while microfilaria-negative samples were PCR-negative. The specificity and sensitivity of the Ssp I PCR assay indicates that this approach has significant potential for improved screening of large human populations for active W. bancrofti infection.

[Identification of vertical transmission of hepatitis B virus from mother to children by direct sequencing a segment of surface gene of hepatitis B virus]

SUBJECTIVE

To explore the reason for the failure to interrupt vertical transmission of hepatitis B virus (HBV) from mother to children in Chinese subjects by vaccination.

METHODS

HBV nucleotide sequences isolated from three sets of mother/children pairs were analyzed. HBV DNA from the surface antigen region encoding the amino acids 101 to 160 of hepatitis B surface antigen (HBsAg) was amplified and sequenced from HBsAg positive mother and their children.

RESULTS

Nucleotide and deduced amino acid sequences were absolutely identical in the mother and children in family one and two respectively. However, there were five nucleotides different in family one's isolates compared with the family two's isolates. All of them were a subtype. In one child of family three, with coexisted HBsAg and anti-HBs, sequencing result revealed a point mutation which predicted a change from glycine to arginine at residue 145 in the second loop of the determinant. The mother and another child had a glycine at this position.

CONCLUSION

This study revealed the vertical transmission linkage of HBV between the mother and children in a molecular level, and also first described a codon 145 immune escape mutant in Chinese vaccinated children.

Rat calcium-sensing receptor is regulated by vitamin D but not by calcium

Parathyroid hormone (PTH) secretion is regulated by extracellular calcium acting through a cell surface calcium receptor (CaR). We have examined the potential regulation of the CaR in the parathyroid glands (PTG) and kidney by calcium and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. Rats fed vitamin D-deficient (-D) diets containing 0.02, 0.4, or 2.0% Ca had a wide range of serum ionized Ca (2.5-5.2 mg/dl) and PTH (22-590 pg/ml) concentrations. PTG CaR mRNA did not vary significantly with ionized calcium or PTH, indicating that hypocalcemia and hyperparathyroidism may not alter CaR expression. However, PTG CaR mRNA was 40% lower in the -D rats than in age-matched rats fed a vitamin D-replete (+D) diet (P < 0.002). Repletion of -D rats with 1,25-(OH)2D3 produced a dose-dependent increase in PTG CaR mRNA. Treatment of +D rats with 100 ng of 1,25-(OH)2D3 increased CaR mRNA by 33% (P < 0.05) and 54% (P < 0.002) in the PTG and by 89% (P < 0.02) and 91% (P < 0.02) in the kidney in two independent experiments. PTG CaR peaked at 16 h (150% of control, P < 0.05) after 1,25-(OH)2D3 administration but returned to normal by 24 h. This upregulation of CaR expression by 1,25-(OH)2D3 may be involved in the suppressive effects of vitamin D compounds on PTH secretion.

Dual-electrode detection for capillary electrophoresis/electrochemistry

The extremely low sample volumes required for capillary electrophoresis and the high sensitivity and selectivity of electrochemical detection make capillary electrophoresis/electrochemistry (CEEC) a very useful method for bioanalysis. In this paper, two types of dual-electrode detectors for CEEC are described. The first employs a ring-disk microelectrode placed in a wall-jet configuration and is used for the selective detection of substances undergoing chemically reversible oxidations. Collection efficiencies obtained for catecholamines with this configuration were between 25 and 35%. The second electrode design consists of two adjacent carbon fibers embedded in an epoxy matrix and is analogous to the parallel dual-electrode configuration used in liquid chromatography/electrochemistry. This configuration can be used to confirm peak identity and purity by operating the electrodes at two different potentials. Alternatively, it is possible to perform simultaneous oxidative and reductive electrochemical detection.

[Direct genotyping and antenatal diagnosis of deletional alpha-thalassemia of the southeast Asian type by polymerase chain reaction technique]

OBJECTIVE

To study the gene of deletional alpha-thalassemia of the Southeast Asian type (SEA) and to perform the antenatal diagnosis.

METHODS

A new method of polymerase chain reaction technique using three primers bridging the breakpoints was carried out for carrier detection and antenatal diagnosis of deletional alpha-thalassemia of the Southeast Asian type. A DNA fragment of about 630bp in size was amplified in case of--SEA alleles, while a 224 bp fragment was amplified in samples without the deletion. Homozygotes, heterozygotes, and normal subjects could be clearly distinguished with the present method.

RESULTS

We used this method in the genotyping and antenatal diagnosis of 10 high risk pregnancies of alpha-thalassemia. 2 homozygotes, 4 heterozygotes, and 4 normal infants were found.

CONCLUSION

The present method is simple and rapid in detection of carriers and antenatal diagnosis of the alpha-thalassemia of southeast Asian type.

Microtubules mediate cellular 25-hydroxyvitamin D3 trafficking and the genomic response to 1,25-dihydroxyvitamin D3 in normal human monocytes

The genomic actions of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) are mediated by the intracellular vitamin D receptor (VDR). Although immunocytochemistry has shown that disruption of microtubular assembly prevents nuclear access of the sterol-VDR complex, the role of microtubules in the response to 1,25(OH)2D3 has not been studied in viable cells. Our studies examined this interaction in normal human monocytes. Monocytes convert 25(OH)D3 to 1,25(OH)2D3 and to 24-hydroxylated metabolites more polar than 1,25(OH)2D3. Microtubule disruption totally abolished the ability of exogenous 1,25(OH)2D3 to suppress its own synthesis and to induce 24-hydroxylase mRNA and activity, without affecting either total 1,25(OH)2D3 uptake or maximal 1,25(OH)2D3-VDR binding. Thus, intact microtubules are essential for 1,25(OH)2D3-dependent modulation of gene transcription. Interestingly, microtubule disruption also decreased monocyte 1,25(OH)2D3 synthesis, not by decreasing the Vmax of monocyte mitochondrial 1 alpha-hydroxylase but through an increase in the Km for 25(OH)2D3. We examined 25(OH)D3 transport. Microtubule disruption did not affect total cellular 25(OH)D3 uptake but reduced its intracellular trafficking to the mitochondria. Thus, microtubules participate in intracellular 25(OH)D3 transport, and their integrity determines normal 1,25(OH)2D3 synthesis.