Drug therapy for hepatitis B

Until recently, IFN has been the only available therapy for chronic HBV infection; however, many new and exciting therapeutic strategies have emerged during the last decade. Recent advances in our understanding of the replicative mechanism of HBV and the development of potent nucleoside analogues have opened a new era in the treatment of HBV. Lamivudine has been introduced as an alternative to IFN, showing at least similar efficacy, but with a wider spectrum of indications and without the adverse effects. Therapeutic vaccination and molecular or gene therapy are being investigated as potential approaches, and aggressive combination therapy is emerging as a promising strategy. Based on the experience with HIV, the future of drug therapy against HBV likely includes combination therapy with 1 or more nucleoside/nucleotide analogues and an immune-modulating agent, such as IFN or a therapeutic vaccine. This combination may act synergistically against HBV and delay or prevent the development of drug-resistant mutants.

Abolition of pentagastrin-stimulated alkaline tide using the carbonic anhydrase inhibitor acetazolamide

BACKGROUND

Alkaline tide is the transient increase in blood and urine pH following stimulation of gastric acid secretion. It is attributed to HCO3- release from parietal cells in parallel with H+ secretion. The enzyme carbonic anhydrase is thought to be responsible for HCO3- production from CO2 and OH- in the parietal cell.

OBJECTIVE

To examine the effect of pretreatment with the carbonic anhydrase inhibitor, acetazolamide, on the alkaline tide phenomenon.

METHODS

Ten patients with dyspepsia and demonstrable alkaline tide were tested on three separate days. The pH and base excess were determined in arterialized venous blood before and 45 minutes after an intramuscular injection of pentagastrin. The pH of the urine was measured before and 120 min after pentagastrin injection. Measurements were performed after pentagastrin alone on day 1, following pretreatment with acetazolamide 60 min before pentagastrin on day 2, and after the administration of acetazolamide alone on day 3.

RESULTS

Following the administration of pentagastrin alone, the blood base excess increased by 1.61 +/- 0.2 mEq/L (mean +/- standard deviation) and the calculated alkaline tide at 45 min was 33.99 +/- 4.49 mEq. On day 2 with prior administration of acetazolamide, base excess decreased by 0.21 +/- 0.39 mEq/L, and the calculated alkaline tide was -3.28 +/- 7.57 mEq, which was significantly lower than on day 1 (P = 0.0001). On day 3, following acetazolamide alone, the base excess values decreased by 0.53 +/- 0.2 mEq/L and the alkaline tide was -10.05 +/- 3.33 mEq; there was no significant difference compared with day 2 (P = 0.44).

CONCLUSION

Pretreatment with acetazolamide abolished the alkaline tide induced by pentagastrin. This finding supports the view that carbonic anhydrase has a major role in the alkaline tide phenomenon.

Transient hepatopulmonary syndrome in a patient with acute hepatitis A

The hepatopulmonary syndrome is defined as the triad of liver disease, hypoxaemia and intrapulmonary vascular dilatation. This syndrome has been described in patients with liver cirrhosis, noncirrhotic portal hypertension, and fulminant hepatic failure, however, there are no previous descriptions of hepatopulmonary syndrome in patients with acute nonfulminant viral hepatitis. We report a 47-year-old, previously healthy man that presented with acute hepatitis A, and developed progressive dyspnoea, platypnoea and orthodeoxia with no evidence of parenchymal or thromboembolic lung disease. PaO2 on room air was 58 mmHg, O2 saturation was 88% and alveolar-arterial O2 gradient was 62%. During his hospitalization serum albumin level decreased to 3.1 g/dl and prothrombin time was prolonged to 16.8 s, however, he remained alert with no signs of hepatic encephalopathy. Contrast echocardiography revealed left heart chamber opacification 3-4 cardiac cycles after the opacification of the right heart chamber, consistent with hepatopulmonary syndrome. During the following days there was a gradual improvement in the patient's condition, with resolution of his dyspnoea and gradual increase of PaO2. Repeat contrast echocardiography and PaO2 determinations, 3 weeks later, were normal. On long-term follow-up the patient remained asymptomatic with normal liver function tests and normal O2 saturation. This report indicates that hepatopulmonary syndrome may be a transient manifestation of acute hepatitis A in the absence of fulminant liver failure.

Viral hepatitis A, B, and C

Mankind probably has known viral hepatitis for many centuries; however, the major and most dramatic developments in our knowledge of these diseases have taken place during the second half of the 20th century. During this relatively short period of time, the infectious nature of hepatitis A, B, and C has been proven, leading to their identification and description. The advent of serologic markers has provided the means for establishing the diagnosis. Epidemiologic studies have provided important information that led to exciting achievements in detection and prevention of transmission. Molecular biology studies and cell culture techniques have established our knowledge of the viral genomes, and led to the development of specific vaccines for hepatitis A and B. Anti-viral therapy has been developed and aggressive combination therapy has emerged as a promising strategy for chronic hepatitis B and C. This article reviews some of the main fields of progress and achievement related to viral hepatitis A, B, and C in the 20th century.

Hepatitis C and alcohol

BACKGROUND

Alcohol abuse and hepatitis C virus (HCV) infection frequently coexist in patients with chronic liver disease. It is widely believed that alcohol and HCV act synergistically in these patients to promote the development and progression of liver damage.

METHODS

A review of the relevant medical literature, identified by computer assisted literature search, was conducted.

RESULTS

It has been established that alcohol consumption is associated with the accelerated progression of liver injury, higher frequency of cirrhosis, and higher incidence of hepatocellular carcinoma. Alcohol abuse is also associated with decreased response to interferon treatment, and there are reports to suggest that patients with HCV cirrhosis, who abuse alcohol, have higher mortality than those who do not. Abstinence may reverse some of these deleterious effects of alcohol, and may even improve the ultimate response to treatment. The mechanism for the synergistic effect of alcohol and HCV is not fully understood, but has been attributed to alcohol's effect on viral replication, or to its effect on the immune system, hepatic iron content, or hepatic regeneration.

CONCLUSIONS

Alcohol has a deleterious effect on HCV associated liver disease. It is recommended that patients with HCV infection abstain from alcohol consumption.

Seroprevalence of Helicobacter pylori and length of stay in a nursing home

BACKGROUND

Helicobacter pylori infection appears to be contracted mainly in childhood, and it is associated with disadvantaged socioeconomic conditions, overcrowding, and living in institutions. In this study we determined the seroprevalence of H. pylori among elderly patients (age > or = 70 years) admitted to a major medical center in Israel, and studied the relationship between seroprevalence of H. pylori and the duration of stay in a nursing home prior to the admission.

PATIENTS AND METHODS

Whole blood from 182 consecutive patients hospitalized at the Rabin Medical Center was tested for the presence of anti-H. pylori IgG using Helisal Rapid Blood Test kit (Cortecs Diagnostics). Multivariate logistic regression analysis was used to study the relation between H. pylori seropositivity and possible predictive factors such as age, gender and duration of stay in a nursing home.

RESULTS

Of the 182 patients included in the study, 80 (44%) were living in nursing homes (NH) and 102 (56%) were living in their own homes (H) prior to admission. Subjects that stayed in nursing homes for more than 15 months were significantly more likely to be seropositive than subjects with a shorter duration of stay (84% and 63% respectively, p = 0.03). Using a multivariate logistic regression analysis on both the NH group and the whole group, seropositivity was found to be significantly associated with duration of stay in a nursing home (p = 0.03 and p = 0.01 respectively). Seropositivity was not associated with age in either group.

CONCLUSIONS

Living in a nursing home is associated with increased risk for H. pylori infection in the elderly. There is a strong correlation between the duration of stay in a nursing home and the prevalence of H. pylori infection.

Viral hepatitis

Viral hepatitis is still one of the most common causes of acute and chronic liver disease worldwide. Major advances have been made in our knowledge of these diseases, many during the past year. Molecular biology and clinical studies have improved our understanding of the mechanisms of antiviral drugs, as well as viral resistance to therapy. The risks of hepatitis A in patients with chronic liver disease have been confirmed, and the efficacy of hepatitis A vaccines in these patients has been proven. Aggressive combination therapy has emerged as a promising strategy for chronic hepatitis B and C, and techniques for immune prophylaxis for hepatitis B are being improved. Liver transplantation has become routine for end-stage hepatitis B virus liver disease, and new strategies to prevent and treat recurrence are being explored. This review discusses the recent advances in our knowledge of hepatitis viruses A through G, focusing on the literature of the past year.

Is greater than normal nocturnal heart rate in children with renal scars a predictor of reflux nephropathy?

BACKGROUND

The existence of renal scars constitutes the major etiologic factor for the development of hypertension during childhood. Elevated blood pressure in this setting can be considered a secondary form of hypertension. Certain forms of secondary hypertension have been associated with a lower than normal nocturnal fall in blood pressure. Resting heart rate per se has recently been reported to be an independent predictor of risk for cardiovascular mortality irrespective of age and the presence or lack of hypertension.

OBJECTIVE

To ascertain the responses of heart rate and blood pressure in normotensive children with renal scars without, however, proteinuria and renal failure.

METHODS

Ten children with renal scars documented by a 99Tc dimercaptosuccinic acid (DMSA) scan were subjected to ambulatory blood pressure monitoring. Ten age-matched and sex-matched healthy children served as the control group. Serum urea and creatinine levels, calculated rate of clearance of creatinine, microalbuminuria, plasma renin activity, and levels of aldosterone and catecholamines were determined for each subject.

RESULTS

Average daytime and night-time systolic and diastolic blood pressures for the two groups did not differ. Subjects in both groups demonstrated the physiologic decrease in blood pressure during sleep (normal 'dipper' response), which was of equal magnitude for these two groups. Mean daytime heart rates were 92+/- 13 beats/min in children with renal scars versus 80+/-11 beats/min in controls (NS). Mean and minimal heart rates during night-time in children with renal scars were found to be significantly greater [79+/-6 versus 65+/-5 beats/min (mean) and 61+/-10 versus 56+/-7 beats/min (minimal), P < 0.01]. Parameters of renal function, plasma renin activity, and levels of aldosterone and catecholamines were similar for these two groups.

CONCLUSION

Despite their having an equivalent physiologic dip in blood pressure during night-time, normotensive children with renal scars have a significantly greater nocturnal heart rate than do control subjects.

Telomeric repeats on small polydisperse circular DNA (spcDNA) and genomic instability

Small polydisperse circular DNA (spcDNA) is a heterogeneous population of extrachromosomal circular molecules present in a large variety of eukaryotic cells. Elevated amounts of total spcDNA are related to endogenous and induced genomic instability in rodent and human cells. We suggested spcDNA as a novel marker for genomic instability, and speculated that spcDNA might serve as a mutator. In this study, we examine the presence of telomeric sequences on spcDNA. We report for the first time the appearance of telomeric repeats in spcDNA molecules (tel-spcDNA) in rodent and human cells. Restriction enzyme analysis indicates that tel-spcDNA molecules harbor mostly, if not exclusively, telomeric repeats. In rodent cells, tel-spcDNA levels are higher in transformed than in normal cells and are enhanced by treatment with carcinogen. Tel-spcDNA is also detected in some human tumors and cell lines, but not in others. We suggest, that its levels in human cells may be primarily related to the amount of the chromosomal telomeric sequences. Tel-spcDNA may serve as a unique mutator, through specific mechanisms related to the telomeric repeats, which distinguish it from the total heterogeneous spcDNA population. It may affect telomere dynamics and genomic instability by clastogenic events, alterations of telomere size and sequestration of telomeric proteins.

Comparison of two bowel preparations for colonoscopy: sodium picosulphate with magnesium citrate versus sulphate-free polyethylene glycol lavage solution

OBJECTIVES

Adequate preparation of the bowel is essential for accurate colonoscopic examination. We compared colonic preparation with sodium picosulphate plus magnesium citrate (SPS-Mg) with sulphate-free polyethylene glycol electrolyte lavage (PEG-EL) solution before colonoscopy, for quality of bowel cleansing, patient discomfort, and side effects.

METHODS

Sixty-eight consecutive patients were randomly assigned to receive either 3 sachets of SPS-Mg (16.5 g each) (n = 39) or 3 L of PEG-EL (n = 29) on the day before colonoscopy. Shortly before the procedure each patient was interviewed to determine the degree of discomfort (1 = none or mild, 2 = moderate, 3 = severe) and side effects. The quality of bowel cleansing was graded by a gastroenterologist who was unaware of the method of preparation (from 1 = poor to 4 = excellent).

RESULTS

Of the 29 PEG-EL patients, four (14%) did not complete the preparation because of side effects. The degree of discomfort was significantly greater with PEG-EL (mean score, 2.3 +/- 0.7) than with SPS-Mg (mean score, 1.4 +/- 0.5; p < 0.01). Nausea and vomiting were significantly more common in the PEG-EL group (38% vs 13%; p < 0.05). Using intention-to-treat analysis, bowel cleansing proved to be significantly better with SPS-Mg than with PEG-EL (mean score +/- SD, 3.05 +/- 0.9 and 2.57 +/- 1.0, respectively; p = 0.036).

CONCLUSIONS

Colonic preparation with SPS-Mg is better tolerated, associated with significantly fewer side effects, and results in higher quality bowel cleansing than preparation with PEG-EL.

Necrotizing fasciitis caused by Staphylococcus aureus

Two patients with rapidly progressive necrotizing fasciitis of a lower extremity due to Staphylococcus aureus as a single pathogen are described. In both patients the portal of entry was attributed to needle puncture (intra-articular injection and intravenous catheter, respectively), followed by bacteremia. Necrotizing fasciitis occurred in a site remote from the needle puncture, suggesting metastatic infection. One patient developed toxic shock syndrome and the other a sunburn-like rash and erythematous mucosae with strawberry tongue. One patient died, and the other required above-knee amputation due to secondary infectious complications. Staphylococcus aureus may mimic the presentation of invasive group A streptococcal infections. A history of needle puncture should alert the physician to the possibility of Staphylococcus aureus infection.

Thrombotic complications in essential thrombocythemia with relatively low platelet counts

Essential thrombocythemia (ET) is often associated with thrombotic and hemorrhagic complications, mostly at platelet counts exceeding 600 x 10(9)/L. There are, however, a few reports of such complications in ET at considerably lower platelet levels and the therapeutic approach to affected patients with relatively low platelet counts is still controversial. In the present study, the first to directly address the issue of hemostatic manifestations at relatively low platelet counts, we have determined the lowest platelet counts associated with such manifestations in 56 consecutive ET patients. Clinical manifestations related to ET were recorded in 46 (82%) patients. Of the symptomatic patients, 32 (70%) had symptoms at platelet counts lower than 600 x 10(9)/L, 23 (50%) at counts lower than 500 x 10(9)/L, 10 (22%) at counts lower than 400 x 10(9)/L, and 6 patients (13%) at platelet counts as low as 300-350 x 10(9)/L. Severe complications occurred at platelet counts lower than 600 x 10(9)/L in 10 patients (22%), lower than 500 x 10(9)/L in 7 (15%), and at lower than 400 x 10(9)/L in 2 (4%). Thrombotic neurologic symptoms were the most common (31 patients, 67%), followed by peripheral vascular symptoms (17 patients, 37%); hemorrhagic complications were relatively rare (3 patients, 7%). In most cases, cessation or improvement of clinical manifestations was observed only after further reduction in platelet counts. In conclusion, thrombotic manifestations, including severe ones, are not uncommon in ET at relatively low platelet counts. We recommend that symptomatic patients with relatively low platelet counts be treated and the platelet counts further reduced well into the lower normal range.

Effect of androgen substrates on the steroidogenic pattern of cumulus cells: correlation with cumulus culture morphology

BACKGROUND

In previous studies, higher progesterone secretion was observed in mature versus immature cumulusoocyte complexes. In mature cumulus mass that become homogeneously spread in culture (type C/D) progesterone secretion was higher than in partially (type B) or totally (type A) aggregated morphology. In sharp contrast, estradiol-17 beta secretion was significantly higher in type A than type C/D cumulus.

PURPOSE

Our purpose was to assess whether the decreased estradiol-17 beta level in type C/D cumulus culture is caused by deficiency of substrates.

METHODS

The different cumulus types were incubated with or without 10(-7) M dehydroepiandrosterone, 4-androstane-3, 17-dione, or testosterone. The levels of estradiol-17 beta, testosterone, and progesterone, were measured after 24 hr of culture.

RESULTS

The addition of dehydroepiandrosterone or 4-androstane-3, 17-dione significantly increased the estradiol-17 beta levels in all types of cumulus cells, whereas the addition of testosterone was less effective. In all types of cumulus cells the testosterone levels increased significantly on adding these androgen substrates. In the type C/D cumulus, the testosterone increased to lower levels compared to type A cumulus cells. In the presence of these androgens progesterone secretion is significantly reduced in type A cumulus cells. In type C/D cumulus cells, however, progesterone levels were significantly higher than in type A. The estradiol-17 beta/ testosterone and progesterone/estradiol-17 beta ratios, which partially resemble the degree of aromatase activity and the degree of selectivity for progesterone secretion, respectively, were higher in type C/D than in type A cumulus cells.

CONCLUSIONS

In type C/D cumulus the significant increase in estradiol-17 beta secretion in the presence of various androgens suggests that, under basal conditions, androgen is less available for estradiol-17 beta biosynthesis compared to type A cumulus. Furthermore, the higher progesterone secretion in type C/D cumulus may suggest that the follicles yielding type C/D cumulus cells are more mature than the follicles yielding type A cumulus.

[Disappointing response of chronic C hepatitis to interferon]

From February 1990 to August 1995 we treated 58 patients with chronic hepatitis C alfa-interferon, 3 million units 3 times weekly for 6 months. Of the 48 patients with adequate follow-up, 34 did not respond to treatment at all. 10 patients responded, but within a few months hepatic enzymes again increased. These 2 groups can be considered failures of interferon treatment. In 4 patients enzymes remained normal for the duration of follow-up, (10-34 months). Even in this small group, 1 patient had a positive test for HCV RNA after completion of treatment. A partial explanation of our disappointing results may be the high prevalence of a subtype of C hepatitis-subtype 1b, which has recently been reported in Israel. This strain is particularly resistant to interferon. The means to define subtypes were not, and as far as we know are not yet available in Israel. Various groups have attempted to improve the outcome of treatment of hepatitis C, which in other hands too was still far from satisfactory. Thus, regimens of interferon utilizing higher doses and longer periods of treatment are being evaluated, as well as the addition of Ribavirin, which hopefully will improve results.

Small polydispersed circular DNA (spcDNA) in human cells: association with genomic instability

Small Polydispersed Circular DNA (spcDNA) was suggested to be associated with genetically unstable cells. However, until now, qualitative and quantitative research has been limited due to the lack of efficient methods for detection and analysis. We developed a two-dimensional (2-D) neutral-neutral gel electrophoresis assay for the identification, characterisation and quantitation of spcDNA. Using this method, we established the relation of spcDNA to genetic and induced genomic instability in human cells, both in vitro and in vivo. Enhanced amounts of spcDNA were found in genetically unstable cells and tissues. spcDNA was detected in a tumor cell-line (HeLa) and in tumor tissue (colon carcinoma) as well as in fibroblasts derived from patients suffering from the genomic instability disease, Fanconi's Anemia. We failed to detect spcDNA in the genetically stable normal human fibroblasts. However, following treatment with the initiating carcinogen MNNG, an induction of spcDNA was observed. The level of spcDNA was quantified according to mitochondrial DNA (mtDNA) standards. In light of these findings, we discuss the possible role of spcDNA as a marker and an enhancer of genomic instability.

Mapping of the entomocidal fragment of Spodoptera-specific Bacillus thuringiensis toxin CryIC

Insecticidal CryI protoxins of Bacillus thuringiensis are activated by proteolysis in the midgut of insects. A conservation of proteolytic cleavage sites in the CryI proteins facilitates the expression of active toxins in transgenic plants to obtain protection from various insects. However, the engineering of CryIC toxins has, thus far, failed to yield applicable resistance to armyworms of Spodoptera species representing common insect pests worldwide. To improve the production of recombinant CryIC toxins, we established a CryIC consensus sequence by comparative analysis of three cryIC genes and tested the stability and protease sensitivity of truncated CryIC toxins in Escherichia coli and in vitro. In contrast to previous data, the boundaries of trypsin-resistant CryIC core toxin were mapped to amino acid residues I28 and R627. Proteolysis of the truncated CryIC proteins showed that Spodoptera midgut proteases may further shorten the C-terminus of CryIC toxin to residue A615. However, C-terminal truncation of CryIC to residue L614, and a mutation causing amino acid replacement I610T, abolished the insecticidal activity of CryIC toxin to S. littoralis larvae, as well as its resistance to trypsin and Spodoptera midgut proteases. Because no CryIC toxin carrying a proteolytically processed N-terminus could be stably expressed in bacteria, our data indicate that, in contrast to other CryI proteins, an entomocidal fragment located between amino acid positions 1 and 627 is required for stable production of recombinant CryIC toxins.

Synergistic activity of a Bacillus thuringiensis delta-endotoxin and a bacterial endochitinase against Spodoptera littoralis larvae

In an attempt to increase the insecticidal effect of the delta-endotoxin crystal protein CryIC on the relatively Cry-insensitive larvae of Spodoptera littoralis, a combination of CryIC and endochitinase was used. CryIC comprising the first 756 amino acids from Bacillus thuringiensis K26-21 and endochitinase ChiAII encoded by Serratia marcescens were separately produced in Escherichia coli carrying the genes in overexpression vectors. The endochitinase on its own, even at very low concentrations (0.1 microgram/ml), perforated the larval midgut peritrophic membrane. When applied together with low concentrations of CryIC, a synergistic toxic effect was obtained. In the absence of chitinase, about 20 micrograms of CryIC per ml was required to obtain maximal reduction in larval weight, while only 3.0 micrograms of CryIC per ml caused a similar toxic effect in the presence of endochitinase. Thus, a combination of the Cry protein and an endochitinase could result in effective insect control in transgenic systems in which the Cry protein is not expressed in a crystalline form.

Influence of diabetes mellitus and glycaemic control on the characteristics and outcome of common infections

The aim of the present study was to elucidate the effect of diabetes and metabolic control on the presentation, sources, pathogens and outcome of common infections. Of 515 patients admitted to three departments of internal medicine because of a suspected acute infection, 132 (26%) had diabetes mellitus. Osteomyelitis was diagnosed in 3% of the diabetic patients and in 1% of patients without diabetes, and infection of the extremities in 7% and 0%, respectively (p = 0.003). Klebsiella sp. caused 24% of urinary tract infections in diabetic patients, versus 13% in patients without diabetes (p = 0.1). The percentage of Staphylococcus aureus infections in diabetic patients was 10% versus 5% in non-diabetic patients (p = 0.06). The gross mortality rate in the diabetic patients was 10%, and in patients without diabetes, 12%. In patients without fatal underlying disorders, mortality in the diabetic patients was 10% (2% in patients with glycosylated haemoglobin (GHb) lower than median, and 17% in patients with GHb higher than median) and in the non-diabetic patients 4% (p = 0.04). Five factors were independently and significantly related to mortality in diabetic patients: acute respiratory distress (very large odds-ratio [OR]), coma (OR 3.8, 95% confidence interval [CI] 1.0-14.3), GHb above the median (OR 3.3, 95% CI 1.8-6.2), the interaction between GHb and absence of a severe underlying disorder (OR 12.0, 95% CI 2.9-50.7) and duration of diabetes (OR of 1.072 for 1-year increment, and 1.42 for a 5-year increment). Choice of empiric antibiotic treatment in diabetic patients with suspected bacterial infection should take into account the preponderance of Klebsiella sp. and Staphylococcus aureus infections. The present results favour an association between poor glycaemic control and a fatal outcome of infectious diseases in diabetic patients.

Digestion of delta-endotoxin by gut proteases may explain reduced sensitivity of advanced instar larvae of Spodoptera littoralis to CryIC

The present study describes the correlation between gut protease activity of lepidopteran larvae of different instars, the inactivation of Bacillus thuringiensis delta-endotoxins in crystalline and noncrystalline forms, and the reduced susceptibility of advanced larval instars of Spodoptera littoralis to the toxin. The original assembly of delta-endotoxins in a crystal structure is essential for causing efficient larval mortality. Denaturation and renaturation (D/R) of delta-endotoxin crystals increased the vulnerability of the toxin molecules to proteolysis, reduced their capability to kill neonate larvae of S. littoralis, but sustained most of their larval growth-inhibition activity. E. coli-produced CryIC delta-endotoxin applied as a fraction of inclusion bodies exerted a growth inhibition effect, similar to the molecules released from the crystals by denaturation and subsequent renaturation. Incubation of CryIC with gut juice of 1st or 2nd instar larvae, left part of the CryIC toxin intact, while the toxin was completely degraded when incubated with gut juice of 5th instar larvae. The degradation rate was consistent with the increase of protease specific activity of the gut juice during larval development. This increase in toxin degradation may account for the loss of sensitivity of 5th instar larvae to CryIC. Specific protease inhibitors such as PMSF and Leupeptin were shown to inhibit gut proteases activity in all instar larvae, while, 1,10 phenanthroline, TLCK and TPCK were effective only in young instar larvae. The differential effect of protease inhibitors on proteases obtained from different larval instars indicated that gut juice protease profiles change with larval age. The observed quantitative and qualitative differences in degradation of delta-endotoxin by larval gut proteases that occur during larval maturation may account for the difference in susceptibility to the delta-endotoxin. This finding should be taken into consideration when designing strategies for the development of transgenic crops expressing delta-endotoxins as potent insecticidal proteins.

Two rules for early prediction of bacteremia: testing in a university and a community hospital

BACKGROUND

Two rules (model 1 and model 2) were previously derived and prospectively validated at the same institution to predict the likelihood of bacteremia. The objective of the present study was to test and compare the performance of the rules in patients admitted to two sites of inpatient care: a university hospital and a community hospital.

METHODS

Clinical and laboratory data (including the variables contained in the two models) were collected within 24 hours in all patients admitted to the Department of Medicine of the Beilinson Medical Center, a university hospital in central Israel, and Emek Hospital, a community hospital in northern Israel, because of an acute infectious disease. The scores of the models were compared with the results of blood cultures.

RESULTS

The percentage of bacteremia was 15% in the university and 18.5% in the community hospital. The area under the receiver-operating characteristic curve was 0.56 + or - 0.04 SE for model 1, and 0.67 + or - 0.04 SE for model 2 in the university hospital; and 0.59 + or - 0.05 SE versus 0.63 + or - 0.04 SE, respectively, in the community hospital. At the best calibration, model 1 defined low-risk groups of 205 patients in the university hospital, and 66 patients in the community hospital, with prevalences of bacteremia of 13% and 15%. The high-risk groups defined by model 1 had prevalences of 30% and 32%. Model 2 defined low-risk groups with prevalences of bacteremia of 7% (8 of 114) and 8% (6 of 76); and high-risk groups with percentages of 29% and 38%.

CONCLUSIONS

The overall accuracy of the two models deteriorated significantly. Both models defined groups at high risk of bacteremia, but the percentages of bacteremia and of death in the low-risk groups do not encourage withholding blood cultures in these patients. The failure of the two models points toward the need for external validation, and for monitoring performance of prediction models over time.