Hospitalizations due to falls in Jewish and Arab children in northern Israel

In Israel, there are no epidemiological data regarding nonfatal childhood falls. A retrospective survey was conducted in order to find epidemiological characteristics of childhood falls among the different populations of northern Israel. During the years 1993 through 1995, 3082 children were hospitalized in Rambam Medical Center (RMC) due to injury. The children were subdivided into the four main populations: Jewish and Arab residents of Haifa region (the main metropolitan area) and Jewish and Arab residents of the Galilee region (the rural region). All of the children who suffered injury that required mechanical ventilation and careful assessment were admitted to the PICU. The charts of the children admitted to the PICU were then further studied. The demographic characteristics of all the cases of falls were statistically analyzed and the annual admission rates due to falls were calculated using the national statistical registrations of children in Israel. Falls were responsible for 1049 admissions due to injury, one third of the total number of children who were admitted due to an injury. Most of the children were five years of age or younger. Two thirds of the total childhood falls were of Arabs. The majority of the admissions were of two major sub-populations of northern Israel: Arab residents of Galilee region (66%) and Jewish residents of Haifa region (34%). Higher admission rate was found among Arab children of the Western Galilee district in comparison with Jewish children of the Haifa district. Most of the children who were admitted to the PICU were Arabs: nearly all of these children were from the rural region. More Arab than Jewish children who fell were admitted to the PICU and the majority of these cases were falls from buildings (private houses). Arab children of the rural region were responsible for 95% of the cases. These falls were mainly in staircases (46%) and from balconies (21%), roofs (11%) and windows (11%). The findings of the present study suggest that young Arab rural children in northern Israel are at high risk to a severe injury due to fall. Possible causes are discussed and a preventative intervention is suggested.

On the performance and inertness of different materials used for the enrichment of sulfur compounds from air and gaseous samples

The performance of the sorbent polydimethylsiloxane (PDMS) is compared to that of the adsorbents Carbotrap and Tenax for the enrichment of volatile and reactive sulfur compounds. These included: 1- and 2-propanethiol, tetrahydrothiophene, 2-thioethanol and 2-ethylthioethanol. Several artifact-forming reactions were identified on both Tenax and Carbotrap including: H2S elimination and dimerization of thiols. Additionally, permanent adsorption was also observed for heavier solutes. These effects are absent when PDMS is applied. This superior performance is explained by the absence of catalytic or adsorptive activity on PDMS.

Zonation of acetate labeling across the liver: implications for studies of lipogenesis by MIDA

Measurement of fractional lipogenesis by mass isotopomer distribution analysis (MIDA) of fatty acids or cholesterol labeled from [(13)C]acetate assumes constant enrichment of lipogenic acetyl-CoA in all hepatocytes. This would not be the case if uptake and release of acetate by the liver resulted in transhepatic gradients of acetyl-CoA enrichment. Conscious dogs, prefitted with transhepatic catheters, were infused with glucose and [1, 2-(13)C(2)]acetate. Stable concentrations and enrichments of acetate were measured in artery (17 microM, 36%), portal vein (61 microM, 5. 4%), and hepatic vein (17 microM, 1.0%) and were computed for mixed blood entering the liver (53 microM, 7.4%). We also measured balances of propionate and butyrate across gut and liver. All gut release of propionate and butyrate is taken up by the liver. The threefold decrease in acetate concentration and the sevenfold decrease in acetate enrichment across the liver strongly suggest that the enrichment of lipogenic acetyl-CoA decreases across the liver. Thus fractional hepatic lipogenesis measured in vivo by MIDA may be underestimated.

15N enrichment of ammonium, glutamine-amide and urea, measured via mass isotopomer analysis of hexamethylenetetramine

Ammonium is an important intermediate of protein metabolism and is a key component of acid-base balance. Investigations of the metabolism of NH(4)(+) in vivo using isotopic techniques are difficult because of the low concentration of NH(4)(+) in biological fluids and because of frequent artifactual isotopic dilution of the enrichment of NH(4)(+) during the assay. A new gas chromatographic mass spectrometric method was designed to monitor the (15)N enrichment and concentration of NH(4)(+) in vivo. These are both calculated from the mass isotopomer distribution of hexamethylenetetramine (HMT) formed by reacting NH(4)(+) with formaldehyde. The enrichment of NH(4)(+) is amplified four times since the HMT molecule contains four atoms of nitrogen derived from NH(4)(+). This allows the measurement of low (15)N enrichment of NH(4)(+), down to 0.1%. (15)N enrichment of urea and of the amide N of L-glutamine are measured by enzymatic release of NH(4)(+) and conversion of the latter to HMT. These new techniques facilitate in vivo investigations of the metabolism of NH(4)(+) and related compounds.

A sensitive HPLC method for the quantification of free and total p-cresol in patients with chronic renal failure

Para-cresol (4-methylphenol) is a volatile phenolic compound which is retained in chronic renal failure. Several recent studies suggest that p-cresol interferes with various biochemical and physiological functions at concentrations currently observed in uremia. Only a few methods are available for the determination of p-cresol concentration in serum. In addition, these methods have only been used for the determination of total p-cresol. In particular, the evolution of free (non-protein bound) p-cresol is of concern, because conceivably this is the biologically active fraction. The concentration of free p-cresol, is, however, markedly lower than that of total p-cresol, in view of its important protein binding. We report a method enabling the measurement of total and free p-cresol concentration in serum of healthy controls and uremic patients. Deproteinization, extraction and HPLC procedure are efficient, without interference of other protein bound ligands and/or precursors of p-cresol or phenol. By means of spiking experiments, the measurement of the UV absorbance over the 200-400 nm wavelength range, and capillary gas chromatography-mass spectrometry, the considered compound is identified as p-cresol. With a fluorescence detection at 284/310 nm as extinction/emission wavelengths the detection limit of p-cresol is 1.3 micromol/l (0.14 microg/ml). Recovery of added p-cresol to normal serum is 95.4+/-4.1%. For free p-cresol and total p-cresol determinations, intra-assay and day-to-day variation co-efficients are 3.2%, 4.2%, 6.9% and 7.3%, respectively. Compared to healthy controls, the serum p-cresol levels are 7-10 times higher in continuous ambulatory peritoneal dialysis patients (CAPD), uremic outpatients, and hemodialysis patients: 8.6+/-3.0 vs. 62.0+/-19.5, 87.8+/-31.7 and 88.7+/-49.3 micromol/l (0.93+/-0.32 vs. 6.70+/-2.11, 9.49+/-3.43, and 9.60+/-5.30 microg/ml) (p<0.05), respectively. The difference is even more important if free p-cresol is considered. This corresponds to a decreased protein binding in uremic patients. We conclude that the present method allows an accurate measurement of both total and free p-cresol, and that the measured concentrations in uremia are in the range which may cause biochemical alterations.

[A method of isothermal gene amplification]

A gene amplification technique applied to the detection of HIV and which can be implemented without programmable thermocyclers is described. The reaction products are high molecular weight strands of DNA that can be detected using simple methods, even without electrophoresis. This is a promising technique for in situ amplification experiments. Our findings show that this amplification method is compatible with the temperature levels encountered in living cells. This technology could thus be the basis for a new class of drugs intended for treatment by gene therapy of certain diseases, including malaria and AIDS.

Limitations of the mass isotopomer distribution analysis of glucose to study gluconeogenesis. Heterogeneity of glucose labeling in incubated hepatocytes

We previously reported (Previs, S. F., Fernandez, C. A., Yang, D., Soloviev, M. V., David, F., and Brunengraber, H. (1995) J. Biol. Chem. 270, 19806-19815) that glucose made in isolated livers from starved rats perfused with physiological concentrations of lactate, pyruvate, and either [2-13C]- or [U-13C3]glycerol had a mass isotopomer distribution incompatible with glucose being made from a homogeneously labeled pool of triose phosphates. Similar data were obtained in live rats infused with [U-13C3]glycerol. We ascribed the labeling heterogeneity to major decreases in glycerol concentration and enrichment across the liver. We concluded that [13C]glycerol is unsuitable for tracing the contribution of gluconeogenesis to total glucose production. We now report isotopic heterogeneity of gluconeogenesis in hepatocytes, even when all cells are in contact with identical concentrations and enrichments of gluconeogenic substrates. Total rat hepatocytes were incubated with concentrations of glycerol, lactate, and pyruvate that were kept constant by substrate infusions. To modulate competition between substrates, the (glycerol)/(lactate + pyruvate) infusion ratio ranged from 0.23 to 3. 60. Metabolic and isotopic steady states were achieved in all cases. The apparent contribution of gluconeogenesis to glucose production (f) was calculated from the mass isotopomer distribution of glucose. When all substrates were 13C-labeled, f was 97%, as expected in glycogen-deprived hepatocytes. As the infusion ratio ([13C]glycerol)/(lactate + pyruvate) increased, f increased from 73% to 94%. In contrast, as the infusion ratio (glycerol)/([13C]lactate + [13C]pyruvate) increased, f decreased from 93% to 76%. In all cases, f increased with the rate of supply of the substrate that was labeled. Variations in f show that the 13C labeling of triose phosphates was not equal in all hepatocytes, even when exposed to the same substrate concentrations and enrichments. We also showed that zonation of glycerol kinase activity is minor in rat liver. We conclude that zonation of other processes than glycerol phosphorylation contributes to the heterogeneity of triose phosphate labeling from glycerol in rat liver.

Determination of types of Enterocytozoon bieneusi strains isolated from patients with intestinal microsporidiosis

To determine the types of Enterocytozoon bieneusi strains associated with intestinal microsporidiosis, we developed a rapid and efficient approach for typing parasites obtained from stool specimens by PCR-restriction fragment length polymorphism (PCR-RFLP). Typing was based on DNA polymorphism of the ribosomal DNA internal transcribed spacer (ITS) region of E. bieneusi. RFLPs generated with two restriction enzymes (NlaIII and Fnu4HI) in PCR-amplified ITS products were used to classify strains into different lineages. This approach was successfully used to differentiate 78 strains that had been obtained from the stools of 65 patients with intestinal microsporidiosis. Among the 78 strains, we found four genetically unrelated lineages, showing the genetic diversity of E. bieneusi. Type I strains of E. bieneusi were found in a majority of the samples, accounting for 51 (78%) of the 65 microsporidiosis cases. In contrast, type II, III, and IV strains were found in only 8 (12%), 3 (5%), and 3 (5%) cases, respectively. All strains of E. bieneusi we have tested so far fall into one of four different lineages, and this study shows that human intestinal microsporidiosis is most often associated with type I strains. PCR-RFLP analysis of the ITS region of E. bieneusi should be useful for epidemiological studies.

[Peripheral adrenal insufficiency in AIDS]

BACKGROUND

Lesions of adrenal glands are common findings at autopsy of patients with acquired immunodeficiency syndrome (AIDS). In contrast the diagnosis of symptomatic adrenal insufficiency is rarely established during the lifetime of these patients.

PATIENTS

We report four new cases and review the literature. All four patients had full blown AIDS with a mean CD4 cell count of 19 mu/L. One or more opportunistic disease was present at the time of diagnostic: cytomegalovirus retinitis in two cases, disseminated Mycobacterium avium infection in two, Kaposi's sarcoma in two and Candida esophagitis in one.

RESULTS

The clinical presentation constantly included fatigue, weight loss, severe orthostatic hypotension and gastrointestinal disturbances. Cutaneous hyperpigmentation was present in three cases. In most cases biological abnormalities were typical, such as hyponatremia, urinary Na/K ratio > or = 1, and hyperkalemia. Serum cortisol levels were within the range of normal in three cases but response to the cosyntropin challenge was typically impaired in all cases. Clinical and biological manifestations returned to normal in 1 to 3 weeks after initiation of therapy with cortisol, associated to fludrocortisone in three cases. However, 13 months after diagnosis, three patients were dead.

CONCLUSION

Usually asymptomatic, diagnostic of symptomatic adrenal insufficiency must be suspected even when clinical presentation is atypical because rapid efficiency of hormonal treatment.

Trinucleotide GAA repeat expansions in seven French Friedreich ataxia families

We collected 7 Friedreich ataxia (FRDA) pedigrees from France. All cases but one family were homozygous for an unstable GAA trinucleotide expansion in the first intron of the frataxin gene. In this peculiar pedigree absence of the GAA expansion supports the notion of possible genetic heterogeneity of FRDA.

Selective modulation of protein kinase A and protein kinase C activities in epidermal growth factor (EGF)-stimulated MCF-7 breast cancer cells

In human MCF-7 breast cancer cells, both protein kinase A (PKA) and different members of the protein kinase C (PKC) family are stimulated upon binding of epidermal growth factor (EGF) to cell surface receptors. Selective stimulation of calcium-dependent PKCs with 10(-6) to 10(-9) M Thymeleatoxin significantly increased the proliferation rate of MCF-7 cells over 5 days in culture. This stimulation was blocked by the PKC antagonist Chelerythrine. In contrast, selective activation of PKA by addition of 1 mM dibutyryl cyclic AMP (dBcAMP) did not affect the proliferation rate of MCF-7 cells. Similarly, activation of the adenylate cyclase by 1 microM Forskolin and inhibition of PKA by the cyclic AMP analogue Rp-cAMPS did not modulate the proliferation rate of these cells. Activation of PKC stimulated the expression of the immediate early gene c-fos but c-myc expression was not significantly enhanced. On the other hand, PKA activation increased both c-myc and c-fos expression in MCF-7 cells. These results suggest that PKA activation and c-myc expression are not obligatory for proliferation of MCF-7 cells.

Tracing gluconeogenesis with deuterated water: measurement of low deuterium enrichments on carbons 6 and 2 of glucose

The contribution of gluconeogenesis to glucose production in vivo can be measured by enriching body water with 0.5% 2H2O and measuring the glucose labeling ratio C6/C2 (Landau et al., J. Clin. Invest. 95, 172-178, 1995). We present further refinements of the measurements of the 2H enrichments on C6 and C2 of glucose. The transfer of 2H from C6 of glucose to hexamethylenetetramine (HMT) and extraction in preparation for gas chromatography-mass spectrometry can be done in a single test tube, without distillation of the intermediate formaldehyde. In addition, extraction of small amounts of HMT is greatly improved by making a HMT-iodine adduct. For C2, glucose is reduced to sorbitol, and 2H on C2 is transferred enzymatically to [U-13C3]pyruvate, forming [U-13C3,2-2H]lactate. The latter is assayed by negative chemical ionization gas chromatography-mass spectrometry of the pentafluorobenzyl derivative. The natural enrichment of the [U-13C3]lactyl ion is only 0.4%, allowing measurements of 2H enrichment down to 0.1%. These techniques were used in dogs infused with 2H2O and in isolated rat livers perfused with buffer containing 1 to 5% 2H2O. Our data reveal a difference in the rate of labeling of C6 and C2 of glucose in vivo. Lastly, in cows infused with [6,6-2H2]glucose, we show that the turnover of glucose can be economically measured by assaying low tracer enrichment (down to 0.1%) via hexamethylenetetramine.

Diagnosis of infections caused by Enterocytozoon bieneusi and Encephalitozoon intestinalis using polymerase chain reaction in stool specimens

OBJECTIVE

To study the usefulness of polymerase chain reaction (PCR) for the species identification of microsporidia in stool specimens obtained from HIV-infected patients with Enterocytozoon bieneusi or Encephalitozoon intestinalis infections.

SETTING

Infectious disease clinic in a university hospital.

PATIENTS

Thirty-seven stool specimens from 29 HIV-infected patients with microsporidiosis were tested. The diagnosis of microsporidian infection was made by light microscopy of stool specimens and species identification was made by transmission electron microscopy of duodenal biopsies. Sixty-one stool specimens from 45 HIV-infected patients without microsporidiosis served as controls.

METHODS

PCR was performed using DNA extracted from stools with two primers sets, one specific for E. bieneusi and one specific for E. intestinalis.

RESULTS

A 1265 base-pair fragment of the small subunit ribosomal RNA (rrs) gene could be amplified from all 31 stool specimens infected with E. bieneusi. In addition, a 930 base-pair fragment of the rrs gene could be amplified from all six stool specimens infected with E. intestinalis. The 61 control stools were negative with both primers.

CONCLUSIONS

These results suggest that a PCR based assay using species-specific primers sets can be used successfully for microsporidian species differentiation from stool specimens, thus obviating the need for invasive biopsy procedures.

Synthesis of [11C]RPR-72840A and its evaluation as a radioligand for the serotonin reuptake site in positron emission tomography

RPR-72840A, an inhibitor of serotonin reuptake, was labelled with carbon-11. The synthesis of the nonradioactive precursor, which exhibited some unexpected chemistry, and its reaction with [11C]phosgene affording [11C]RPR-72840A are described. Biodistribution studies in rats and PET studies in baboons were conducted to evaluate [11C]RPR-72840A as a tracer for PET imaging of the serotonin reuptake system.

Contributions of liver and kidneys to glycerol production and utilization in the dog

The classical concept holds that liver and kidneys are the main sinks of glycerol released by adipose tissue. However, rates of glycerol appearance (Ra) exceed the rate of glycerol delivery to liver and kidneys. We measured the hepatic and renal contributions to glycerol production and utilization in anesthetized dogs that were fasted either overnight or for 24 h after 3 days on a carbohydrate-free diet. Dogs were infused with [2H5]glycerol, and the concentration and 2H enrichment of glycerol were measured across liver and kidney. After a baseline period, either norepinephrine or glucose plus insulin was infused to alter the rate of glycerol production. Our study shows that the production of glycerol by liver and kidneys amounted to 4-9% and 4-7% of the Ra of glycerol, respectively. Uptake of glycerol by liver and kidneys amounted to 26-30 and 10-19% of the Ra of glycerol, respectively. Thus, contrary to the classical concept, the bulk of glycerol utilization occurs in nonhepatic, nonrenal tissues that have very low glycerol kinase activity per gram.

Detection and species identification of intestinal microsporidia by polymerase chain reaction in duodenal biopsies from human immunodeficiency virus-infected patients

Polymerase chain reaction (PCR) was used for the detection of microsporidian DNA in duodenal biopsies obtained from 28 human immunodeficiency virus (HIV)-infected patients with intestinal microsporidiosis. Duodenal biopsies from 23 HIV-infected patients without microsporidiosis served as controls. A generic primer set for human microsporidia was used at first for the PCR. Amplified products were detected in 26 (93%) of 28 biopsies from patients with intestinal microsporidiosis. All control biopsies were negative. Microsporidia species were identified using Southern blot hybridization with specific probes for Enterocytozoon bieneusi and Encephalitozoon intestinalis. This technique confirmed the transmission electron microscopy-based species identification. Similar results were obtained using PCR with species-specific primer sets for E. bieneusi and E. intestinalis. PCR testing of intestinal biopsy specimens can be used successfully for rapid detection and species differentiation of intestinal microsporidia and thus could be a valuable alternative to transmission electron microscopy.

Assay of the 13C and 2H mass isotopomer distribution of phosphoenolpyruvate by gas chromatography/mass spectrometry

The 13C mass isotopomer distribution of liver phosphoenolpyruvate (PEP) yields important information on the regulation of gluconeogenesis and the citric acid cycle. A convenient technique is presented for measuring the mass isotopomer distribution of PEP in tissue extracts. The procedure involves reduction of extant pyruvate to lactate with NaBH4, enzymatic conversion of PEP to pyruvate, extraction of pyruvate hydroxamate and gas chromatographic/mass spectrometric determination of pyruvate hydroxamate di-tert-butyldimethylsilyl derivative. When PEP is labeled with 2H, the enzymatic conversion of PEP to pyruvate results in the loss of 2H. Therefore, to assay the enrichment of [2H]PEP, the tissue extract is chromatographed on an anion-exchange column. The fraction containing PEP is treated to form PEP tri(trimethylsilyl) derivative. The procedures were applied to liver PEP labeled using [U-13C3]lactate, [U-13C3]glycerol or 2H2O. The results show the compatibility between the mass isotopomer distributions of PEP and glucose in rat livers perfused with [U-13C3]lactate or [U-13C3]glycerol. There is a 78% isotopic equilibration of 2H enrichment between the hydrogens on C-3 of liver PEP and the hydrogens of water in 2 day fasted rats.

Assay of the deuterium enrichment of water via acetylene

A technique is presented for measuring the 2H enrichment of water in biological samples when this enrichment is greater than 0.2%. The sample is reacted with calcium carbide to form acetylene gas, which is determined by gas chromatography electron impact ionization mass spectrometry. Ion-molecule reactions, resulting in proton abstraction, are minimized by lowering the electron ionization energy from the usual 70 eV to 45 eV. This technique is much more rapid and economical than the classical isotope ratio mass spectrometric assay of the enrichment of hydrogen gas derived from reduction of water.