Activities of ertapenem, a new long-acting carbapenem, against penicillin-sensitive or -resistant pneumococci in experimental meningitis

The penetration of ertapenem, a new carbapenem with a long half-life, reached 7.1 and 2.4% into inflamed and noninflamed meninges, respectively. Ertapenem had excellent antibacterial activity in the treatment of experimental meningitis due to penicillin-sensitive and -resistant pneumococci, leading to a decrease of 0.69 +/- 0.17 and 0.59 +/- 0.22 log(10) CFU/ml x h, respectively, in the viable cell counts in the cerebrospinal fluid. The efficacy of ertapenem was comparable to that of standard regimens (ceftriaxone monotherapy against the penicillin-sensitive strain and ceftriaxone combined with vancomycin against the penicillin-resistant strain). In vitro, ertapenem in concentrations above the MIC was highly bactericidal against both strains. Even against a penicillin- and quinolone-resistant mutant, ertapenem had similar bactericidal activity in vitro.

[Phenotype of patients showing hearing impairment based on the 35delG mutation in the connexin 26 gene]

BACKGROUND

Hereditary hearing impairment constitutes a heterogeneous class of disorders showing different patterns of inheritance and involving multiple genes. Mutations in the GJB2 gene, especially the 35delG mutation, have been established as a major cause of inherited and sporadic nonsyndromic hearing impairment in different populations.

METHODS

We analyzed 14 northeast Hungarian families and 69 sporadic cases with nonsyndromic hearing impairment for the 35delG mutation. Sixty-five patients showing a homozygous 35delG mutation were examined regarding their audiologic phenotype.

RESULTS

In general, these patients (70%) showed a prelingual, sensorineural, bilateral, symmetric hearing impairment without progression. The audiograms demonstrated sloping as well as flat patterns.

CONCLUSIONS

The severity of hearing impairment varied in 30% of all analyzed patients, making genetic counseling difficult.

[Recovery of hearing: results of delayed medical treatment in patients with idiopathic sudden hearing loss]

For the treatment of idiopathic sudden sensorineural hearing loss (ISSNHL), a variety of studies about intravenous drug administration with the beginning of treatment in the early period of less then one week after the onset of hearing loss have been performed. In contrast, very little information is available about the efficacy of intravenous drug therapy for ISSNHL with the beginning of treatment later than four weeks after the onset of hearing loss. In a retrospective chart review we studied the treatment results of 57 patients with ISSNHL with beginning of treatment later than four weeks after the onset of hearing loss with no spontaneous recovery of hearing. Patients received a treatment with intravenous administration of Dextran (concentration 40 g/l with NaCl 0.9%) and Procain-HCl (a derivative of the local anaesthetic lidocaine,400-800 mg in a 500 ml rheologic infusion of Dextran 40). 25% of the patients showed a significant improvement of 10 dB or more in hearing threshold at 1000 Hz measured in bone-conducted pure tone audiometry. In a subjective evaluation 53% of the patients noticed a subjective improvement of their individual hearing thresholds.

Substitutions in the conserved C2C domain of otoferlin cause DFNB9, a form of nonsyndromic autosomal recessive deafness

DFNB, the nonsyndromic hearing loss with an autosomal recessive mode of inheritance constitutes the majority of severe to profound prelingual forms of hearing impairment, usually leading to inability of speech acquisition. We analyzed a consanguineous family with autosomal recessive deafness which has been shown to segregate within chromosomal region 2p23.1 (DFNB9; MIM 601071). By SSCP analysis and DNA sequencing of the 48 exons of the DFNB9 gene, coding for otoferlin, previously reported mutations in OTOF were excluded. Next to a frequent T > C single nucleotide polymorphism in exon 8, two novel mutations linked in exon 15 of the OTOF long splice form were identified comprising substitutions at positions 490 (Pro > Gln) and 515 (Ile > Thr), both located in the conserved Ca(2+) binding C2C domain of this peptide. Comparisons of homology using human and mice otoferlins and closely related peptides and computer simulation analyses suggest that changes in the mutated segment's secondary structure affect the Ca(2+) binding capacity of the C2C domain in otoferlin.

Assessment of denaturing high-performance liquid chromatography (DHPLC) in screening for mutations in connexin 26 (GJB2)

Mutations in the gene GJB2 encoding connexin 26 (Cx26), a gap junction protein, have been shown to be responsible for a majority of recessive nonsyndromic hereditary hearing impairment in children. Over 60 different mutations in Cx26 have been reported. To obviate the need for direct sequencing of each specimen, a variety of screening techniques have been used to detect mutations in Cx26. However, each of these methods has significant shortcomings including expense, time consumption, and limited sensitivity. Denaturing high-performance liquid chromatography (DHPLC) has been recently introduced as a rapid and highly sensitive method of detecting sequence alterations. We have assessed the efficacy of DHPLC as a screening assay for detecting mutation in Cx26 coding region in 154 patients with hereditary hearing impairment. The GJB2 coding exon was amplified in one or two fragments, analyzed by DHPLC, and sequenced. Sequence analysis identified sequence variations in 34 patients concordant with abnormal DHPLC results. Three novel Cx26 mutations were identified: a single base pair substitution 511G>A, a 4 bp insertion 504insAACG, and a 3 bp deletion 358delAGG in three unrelated patients. In 120 patients with normal Cx26 sequence, DHPLC was normal. These results yield sensitivity and specificity of 100% for DHPLC-based detection of Cx26 mutations, and demonstrate that DHPLC is a highly sensitive and specific method of screening for sequence variations in Cx26 that is time and labor efficient. Further, our experience suggests that DHPLC screening alone followed by DNA sequencing only when DHPLC is abnormal may be adequate for identification of all sequence alterations in Cx26.

NAD degradation and regulation of CD38 expression by human monocytes/macrophages

In recent years, evidence has accumulated that NAD+ serves as a precursor of metabolites that are involved in a number of regulatory processes. In this work we show that extracellularly added NAD+ was rapidly degraded by intact human monocytes to nicotinamide and ADP-ribose. Besides these main products, minor amounts of AMP, ADP and cADP-ribose were formed. Expression of CD38, which has been identified as NAD+-glycohydrolase (EC 3.2.2.6) degrading NAD+ into nicotinamide and ADP-ribose, was determined on freshly isolated human monocytes by flow cytometry and RT-PCR. Upon ligation with anti-CD38 mAb, CD38 underwent internalization, shedding and new expression. As monocytes possess an intracellular CD38 pool, it could serve as a source for newly expressed CD38. Differentiation of monocytes to macrophages resulted in down-regulation of surface expression of CD38. This decrease correlates with a reduction in NADase activity, indicating that the amount of functional active CD38 molecules decrease during differentiation. As CD38 mRNA was found to be diminished in macrophages, regulation of the gene product seems to occur at the level of transcription or mRNA stability.

Frequency of the recessive 30delG mutation in the GJB2 gene in Northeast-Hungarian individuals and patients with hearing impairment

Mutations in the GJB2 gene, which encodes a gap junction protein (connexin 26) account for up to 50% of cases of congenital autosomal recessive non-syndromic hearing impairment. A single mutation, 30delG, is responsible for 70% of this autosomal recessive hearing loss in Europe. This study describes the 30delG mutation analysis of 23 Hungarian families (64 individuals) with at least two subjects with congenital non-syndromic hearing defect and of 52 unrelated individuals from the Northeastern population of Hungary. In all patients, non-progressive hearing impairment varied from moderate to profound involving all frequencies. DNA was tested by PCR based restriction enzyme assay (BSiYI). Sixty-four percent of the patients displayed this one base deletion in GJB2. Out of these, 65.9% were homozygous for this mutation and 34.1% were heterozygotes. The latter showed compound heterozygosity since in these 14 patients, eight previously reported different nucleotide changes were observed on the second allele. The carrier frequency of the 30delG mutation among control group was one in 10.4 (9.6%). This high frequency of 30delG corresponds more to frequencies reported in Southern than in North Europeans.

Elevated carbohydrate antigen 19-9 (CA 19-9) in patients with Echinococcus infection

The carbohydrate antigen 19-9 (CA 19-9), a determinant (sialylated lacto-N-fucopentaose 119) of a circulating oligosaccharide antigen, is a frequently used tumor marker. Echinococcus spp. infects humans throughout the world and may be able to synthesize closely related molecules which could interfere with the measurement and interpretation of CA 19-9 concentration. The main objective of the present study was to determine the range of CA 19-9 levels in the sera of patients infected by E. granulosus (cystic hydatide disease; CYSHD) or E. multilocularis (alveolar hydatide disease; ALVHD). Serum samples were collected from patients (aged 10-85 years) over a period of 5 years: from 19 patients with CYSHD and from 20 patients with ALVHD. Infection was confirmed by positive Echinococcus serology and clinical evidence provided by imaging and/or histopathological findings. CA 19-9 was detectable in 13 patients with CYSHD (13.5 +/- 8.5 kU/l) and 13 patients with ALVHD (30.0 +/- 21 kU/l; p < 0.05). Thus ALVHD patients exhibited a significantly higher plasma level of CA 19-9 than CYSHD patients. The serum level of CA 19-9 assessed with an increased cut-off value (> 22 kU/l) was elevated in nine (45%) of 20 ALVHD patients compared to two (11%) of 19 CYSHD patients (p < 0.05). Sera from patients with Echinococcus multilocularis infection contain substances which cross-react with CA 19-9. These substances originate either from the parasite or are synthesized by the host in response to the infection, and possibly bear the Lewis-a antigen or closely related structures which are recognized by anti-CA 19-9 antibodies. Our findings are relevant to the investigation of patients presenting with cystic lesions for which the differential diagnosis includes an infectious or neoplastic origin.

[An attempt to identify the most frequent genomic mutations responsible for isolated deafness in patients after cochlear implantation]

The aim of this study was to identify subjects with 35delG mutation of GJB2 gene as the most frequent genetic cause of deafness. Deaf patients receiving cochlear implantation at the ENT Clinic at University of Medical Sciences in Poznań and their family members were recruited to the study. Peripheral blood lymphocytes DNA was amplified in allele-specific PCR and analysed for single strand conformation polymorphism (SSCP) to detect mutation at DFNB1 locus. 35delG mutation at both alleles was found at 42.9% of deaf patients and 29.4% of health relatives were found to be carrier of the mutation at one allele. The study is thought to be a first step in analysis of typical mutations in Polish deaf population.

5,10-methylenetetrahydrofolate reductase common mutations, folate status and plasma homocysteine in healthy French adults of the Supplementation en Vitamines et Mineraux Antioxydants (SU.VI.MAX) cohort

The 677cytosine mutation identified in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been frequently associated with an elevated plasma homocysteine concentration. The aim of the present study was to determine the impact of this MTHFR common mutation on plasma and erythrocyte folate (RCF) and plasma total homocysteine (tHcy) concentrations in healthy French adults. A cohort of 291 subjects living in the Paris area and participating in the Supplementation en Vitamines et Mineraux Antioxydants (SU.VI.MAX) study were analysed to assess the impact of MTHFR polymorphism 677C-->T on folate status and plasma tHcy concentration. The frequency of the mutant homozygote for 677C-->T polymorphism (677TT genotype) in the present cohort was 16.8%. There were significant differences in plasma tHcy between 677CC, 677CT and 677TT genotype groups. The RCF concentrations were significantly different between each genotype, the lowest levels being associated with the 677TT genotype. When segregated by gender, no differences in tHcy between homozygous 677TT, heterozygous 677CT and wild-type 677CC genotype groups in women were observed. The fasting tHcy in women was unrelated to the 677C-->T mutation. However, tHcy was significantly increased in men with the homozygous 677TT genotype. We also analysed the possible implication of a second new MTHFR polymorphism (1298A-->C) in subjects with mild hyperhomocysteinaemia (4th quartile of homocysteinaemia; tHcy >11.1 micromol/l). The polymorphism 1298A-->C did not have a notable effect on tHcy or on the RCF levels. Our observations confirm a relatively high frequency of the 677TT genotype in the French population. Women with this genotype did not show the same increase in tHcy observed in men. In the present study dietary folate intake was not measured. Thus, the interaction of dietary folate with the MTHFR genotype in the French population needs further study.

[Mutational analysis of the connexin26 gene in sporadic cases of moderate to profound deafness]

Non-syndromic neurosensory recessive deafness (NSRD) is one of the most common human sensory disorders. Mutations in the connexin 26 gene have been established as a major cause of inherited and sporadic non-syndromic deafness in different populations. The CX26 gene encodes the gap junction protein connexin 26 (beta-2, GJB2), whose expression was shown in several tissues and in the cochlea. The 30delG mutation is the most frequent mutation in the CX26 gene. It represents a deletion of guanosine (G) in a sequence of six Gs extending from position 30 to 35 of the CX26 cDNA. The deletion creates a frameshift resulting in a premature stop codon and a non-functional intracellular domain in the protein. The 30delG mutation can be detected at the molecular level using PCR followed by BsiYI digestion. We screened 164 mainly German patients with non-syndromic sporadic deafness for this mutation to determine its distribution in the German population. The frequency of the mutation in our analyzed patients was lower than in other studies and therefore indicates its dependency on geographically distinct populations.

A polymorphism (80G->A) in the reduced folate carrier gene and its associations with folate status and homocysteinemia

5-methyltetrahydrofolate is the predominant form of folate in plasma. It may be the preferred substrate for transport via the reduced-folate carrier (RFC). We isolated a cDNA for the reduced folate carrier (RFC-1) from human skin fibroblasts. A common polymorphism at position 80 in exon 2 of RFC-1 was identified. This polymorphism changes a guanine (G) to an adenine (A), abolishing a CfoI restriction site. Using genomic DNA samples from 169 healthy subjects, we identified 27.1% GG homozygotes, 21.9% AA homozygotes, and 50.9% GA heterozygotes. We explored the impact of this polymorphism, separately and in combination with the 677C->T polymorphism in the methylenetetrahydrofolate reductase gene, on folate status and total homocysteine levels. We found a moderate, but significant, increase in total homocysteine levels in doubly homozygous 80GG/677TT subjects as compared to 80GG/677CC (P = 0.01) or 80GG/677CT (P = 0.04) subjects. In addition, individuals who were 80AA/677CT had higher plasma folate levels than those who were 80GG/677CT (P = 0.02).

The effect of 677C-->T and 1298A-->C mutations on plasma homocysteine and 5,10-methylenetetrahydrofolate reductase activity in healthy subjects

We have studied the effect of common mutations (677C-->T and 1298A-->C) of the methylenetetrahydrofolate reductase (MTHFR) gene in sixty-six healthy French subjects, aged 27-47 years. Serum folate, vitamin B12, and plasma total homocysteine were measured as well as the specific activity of MTHFR in lymphocytes. The frequency of subjects homozygous for the 677TT genotype was 18%, and that of those homozygous for the 1298CC genotype was 12.5%. The frequency of individuals heterozygous for both mutations was 23.5%. The 1298A-->C mutation was associated with decreased MTHFR specific activity in subjects with both 677CC and 677CT genotypes. This activity was 60% for the 677CC/1298AC genotype and 52% for the 677CC/1298CC genotype when compared with the MTHFR specific activity of the 677CC/1298AA genotype. Heterozygotes for both mutations (677CT/1298AC genotype) had 36% of the reference specific activity. Although homocysteine levels in 677TT and 1298CC genotype subjects were higher than for other genotypes, no significant differences were observed among different genotypes. This may be due to high serum folate level in our samples, and suggests that folate therapy may be useful to prevent hyperhomocysteinaemia in homozygous mutant subjects.

Novel dialysis cannulas: are they worth the higher price tag?

Accessory hemodialysis equipment, including dialysis cannulas, usually lack controlled and independent testing before being introduced onto the market. The aim of this study is a prospective comparison of a newly designed curved-tip dialysis cannula with a standard dialysis cannula of the same size from the same manufacturer. Fifteen chronic dialysis patients were enrolled onto a prospective 4-month crossover study. All patients had arteriovenous fistulas, except for two patients with polytetrafluoroethylene grafts. The routinely used standard cannulas were replaced by either a curved-tip 15G cannula or a new standard 15G cannula from the same manufacturer. The two cannulas were compared with respect to puncture-related pain and/or problems and bleeding complications, as well as blood-flow dynamics. Venous and arterial access pressures were recorded at blood-flow rates of 100 to 400 mL/min. Linear regression analyses of arterial and venous pressure profiles showed the same regression lines for the standard and curved-tip cannulas. Plasma haptoglobulin levels and occlusion times necessary to stop bleeding after removal of the cannulas did not differ between the two cannulas. Both patients and nurses independently reported equal puncture-related pain and/or problems for both cannulas on visual analogue scales. No correlation was found between puncture problems reported by nurses and puncture pain reported by patients. The curved-tip cannula does not offer an advantage compared with the less expensive standard cannula. Controlled testing of advertised advantages by manufacturers of accessory equipment should be a prerequisite before introduction into routine clinical treatment.

Proinflammatory effects in experimental mesangial proliferative glomerulonephritis of the immunosuppressive agent SDZ RAD, a rapamycin derivative

BACKGROUND/AIM

The new immunosuppressant SDZ RAD, a rapamycin derivative, inhibits growth factor driven cell proliferation. SDZ RAD designed for transplantation may also be a candidate agent to treat inflammatory kidney diseases. Therefore, we investigated the effects of SDZ RAD in two different animal models of glomerulonephritis, in anti- Thy1.1 nephritis and in acute puromycin aminonucleoside (PAN) nephrosis.

METHODS

Eighty-seven male Wistar rats were investigated. Anti-Thy1.1 nephritis: healthy rats (n = 9), SDZ RAD-treated healthy rats (n = 6), nephritic rats (n = 9), SDZ RAD placebo treated nephritic rats (n = 6), SDZ RAD-pretreated nephritic rats (n = 9), and early (n = 6) as well as delayed (n = 6) SDZ RAD-posttreated nephritic rats. PAN nephrosis: healthy rats (n = 6), SDZ RAD-treated healthy rats (n = 6), nephritic rats (n = 12), and SDZ RAD-pretreated nephritic rats (n = 12). In a separate study, 12 male Sprague-Dawley rats were analyzed in anti-Thy1.1 nephritis: healthy rats (n = 3), nephritic rats (n = 3) and pretreated nephritic rats (n = 6). SDZ RAD and SDZ RAD placebo were given at single doses of 2.5 mg/kg body weight per day by gavage. The experiments lasted until days +2 and +9 after induction of anti-Thy1. 1 nephritis and until day +13 in the case of PAN nephrosis.

RESULTS

In anti-Thy1.1 nephritis, SDZ RAD demonstrated marked proinflammatory effects in a time-dependent manner, as reflected by severe focal damage to glomerular histology including inhibition of mesangial cell proliferation, reduction of creatinine clearance, and increase in plasma creatinine levels as well as proteinuria. Almost identical results were obtained in both rat strains. In contrary, SDZ RAD ameliorated significantly the development of PAN nephrosis. Animals pretreated by this agent showed a significant reduction of proteinuria and of glomerular invasion of monocytes/macrophages.

CONCLUSION

Some caution is warranted for the use of SDZ RAD in inflammatory glomerular diseases, since it accentuated glomerular damage induced by anti-Thy1.1 antibodies.

Judgment analysis in clinical nephrology

To ameliorate the clinical performance of nephrologists, improving their clinical judgment is crucial. No methodology for judgment analysis in nephrology is currently available. Therefore, we designed a trial to assess the intraphysician consistency of the judgment of typical non-end-stage renal disease (ESRD) patients by 24 board-certified nephrologists. The participants were asked to analyze cases to determine the interobserver variability with respect to diagnosis, therapy, prognosis, and strategy of follow-up. They were unaware that every patient was presented on 2 occasions separated by a period of 6 months. Of the 1,288 questionnaires that were completed, 28 cases belonged to 1 of the following 3 groups: (A) patients once with, once without renal histology, (B) patients twice without histology, and (C) patients twice with histology. Only cases of group (A) differed at the 2 occasions of assessment with respect to knowledge of histology. The results from the first and second assessment were compared and analyzed. The median (95% confidence interval) percentages of changed diagnoses were 64% (59% to 68%), 50% (44% to 62%), and 33% (26% to 47%) in groups A, B, and C, respectively, indicating large intraobserver variability. The frequency of changes in diagnoses declined with the degree of confidence in the first diagnosis in all 3 groups. The subjective desire to know the histology was without impact on the frequency of changes in diagnoses. However, a knowledge of the histology enhanced the degree of confidence in the diagnoses. Interestingly, the enormous variability in changing diagnoses from one analysis to the other was not reflected by corresponding changes in the judgment of prognosis, therapy to be prescribed, or strategy of follow-up. The individual judgment with respect to diagnosis of clinical cases is inconsistent and highly dependent on the subjective degree of confidence in the diagnosis. The practical relevant consequences traditionally derived from a diagnosis (therapy, prognosis, and strategy of follow-up) are only marginally, if at all, affected by changing the diagnosis. Thus, the utility of "diagnosis" for judgment analysis in clinical nephrology should be reconsidered.

Five-year audit of ambulatory 24-hour esophageal pH-manometry in clinical practice

BACKGROUND

Esophageal function testing was developed to aid diagnosis in patients with negative endoscopy. Although combined 24-h esophageal pH-manometry is now commercially available, its routine clinical effectiveness has not yet been studied.

METHODS

From 1992 to 1996 we evaluated 303 consecutive patients who were first-time referrals to our unit for 24-h esophageal pH-manometry. The referral indications were gastroesophageal reflux disease, 47.2%; dysphagia, 18.5%; non-cardiac chest pain, 14.9%; connective tissue disease, 13.2%; and symptomatic patients after antireflux surgery, 6.3%.

RESULTS

Overall, esophageal function testing altered the diagnosis of 44% of the patients, confirmed it in 38%, and specifically changed the management of 66%. The final clinical 'diagnosis' was reflux disease, 54% (32% with non-specific esophageal motility disorder); connective tissue disease, 9.9%; achalasia, 9.6%; other specific esophageal motility disorders, 3.3%; non-specific esophageal motility disorders, 6.9%; and normal, 16.2%. The cost per testing was estimated to be US$305 and per change in management US$465.

CONCLUSION

Combined 24-h pH-manometry has been shown to be a useful and cost-effective test for the management of selected patients in whom the primary investigation was insufficient.

Ambulatory nocturnal oximetry and sleep questionnaire-based findings in 38 patients with end-stage renal disease

BACKGROUND

Patients with end-stage renal diseases (ESRD) have an increased risk of sleep-disordered breathing. With regard to this disorder, controversy persists about prevalence, cost-effective assessment and socio-economical relevance.

METHODS

Therefore, we performed, for the first time, overnight ambulatory oximetry in combination with a sleep questionnaire in 38 unselected patients with ESRD and 37 healthy controls. An oxygen desaturation index (ODI) >15, defined as >15 falls in oxygen saturation of > or =4% per h, was observed more frequently in ESRD patients than in healthy controls (47 vs. 3%, P<0.001).

RESULTS

In general, the results derived from the assessment of the Epworth Sleepiness Scale (ESS) as well as those from the visual analogue scale (VAS) did not reflect the ODI values of the respective patient population. Interestingly, 88% of ESRD patients with the questionnaire finding 'excessively loud snoring' had an ODI of >15 as compared with 13% without this complaint (P<0.05). Furthermore, 77% of ESRD patients with a systolic blood pressure >140 mm Hg and a body mass index (BMI) >25, had an ODI of >15. The percentage of ESRD patients with a professional activity was higher in the absence of sleep-disordered breathing (63 vs. 21%, P<0.05).

CONCLUSION

'Excessively loud snoring' and a BMI >25 combined with hypertension are risk factors for sleep-disordered breathing in ESRD patients. Nocturnal oxygen desaturations are assessed efficiently by ambulatory oximetry and correlate with relevant biological and socio-economical parameters in ESRD patients.