Progressive, Long-Term Hearing Loss in Congenital CMV Disease After Ganciclovir Therapy

BACKGROUND

Long-term hearing outcomes among children with symptomatic congenital cytomegalovirus (CMV) disease who received 6-week ganciclovir therapy early in life are unknown.

METHODS

Longitudinal study of 76 children with symptomatic congenital CMV disease, born 1983-2005, who were categorized into three groups: group A treated with ganciclovir; group B untreated who had microcephaly, chorioretinitis, or sensorineural hearing loss (SNHL; ≥25 dB) diagnosed in the first month of life (congenital); and group C untreated who did not meet criteria for group B.

RESULTS

Patients in groups A (n = 17), B (n = 27), and C (n = 32) were followed to median age of 13, 11, and 13 years, respectively. In group A, patients received ganciclovir for median of 40 (range, 11-63) days; 7 (41%) had grade 3 or 4 neutropenia. Congenital SNHL was diagnosed in 11 (65%) patients in group A, 15 (56%) in group B, and none in group C. Early-onset SNHL was diagnosed between ages ≥1-12 months in an additional 4 (24%), 6 (22%), and 8 (25%) patients in groups A, B, and C, respectively. By the end of follow-up, 12 (71%), 16 (59%), and 7 (22%) of patients in groups A, B, and C, respectively, had severe (>70 dB) SNHL in the better-hearing ear.

CONCLUSIONS

In this study, most patients with symptomatic congenital CMV disease and congenital or early-onset SNHL eventually developed hearing loss severe enough to have been potential candidates for cochlear implantation, with or without 6-week ganciclovir therapy. Understanding long-term hearing outcomes of patients treated with 6-month oral valganciclovir (current standard of care) is needed.

Middle Ear Effusion in Children With Congenital Cytomegalovirus Infection

BACKGROUND

Sensorineural hearing loss (SNHL) is well described in children with congenital cytomegalovirus (CMV) infection, but limited data are available on middle ear effusion (MEE) occurrence in this population. We assessed the prevalence of MEE and the degree of transient hearing change associated with MEE among children with congenital CMV infection.

METHODS

Children with congenital CMV infection enrolled in a longitudinal study received hearing and tympanometric testing during scheduled follow-up visits annually up to 6 years of age. We used a generalized linear mixed-effect logistic regression model to compare the odds of MEE, defined as type B tympanogram (normal ear canal volume with little tympanic membrane movement) among patients categorized as symptomatic or asymptomatic based on the presence of congenital CMV-associated signs in the newborn period.

RESULTS

Forty-four (61%) of 72 symptomatic and 24 (28%) of 87 asymptomatic patients had ≥1 visit with MEE. After controlling for the number of visits, symptomatic patients had significantly higher odds of MEE (odds ratio: 2.09; 95% confidence interval: 1.39-3.14) than asymptomatic patients. Transient hearing decrease associated with a type B tympanogram ranged from 10 to 40 dB, as measured by audiometric air-bone gap in 11 patients.

CONCLUSIONS

Among children with congenital CMV, MEE can result in transient hearing decrease, which can reduce the efficacy of a hearing aid in those with SNHL. It is warranted that children with congenital CMV infection and SNHL receive routine audiologic and tympanometric testing to better manage hearing aid amplification levels.

Post Anaesthesia Care Unit Discharge: A Clinical Scoring System versus Traditional Time-based Criteria

This prospective cohort analysis compared the efficiency of time-based discharge criteria (Group 1) to a modified clinical scoring system (Group 2), incorporating the assessment of pain and temperature, in the post anaesthesia care unit (PACU). Two consecutive series of patients (n=292) were assessed following general anaesthesia for various surgical procedures. The time taken for patients to satisfy their respective discharge criteria was recorded as PACU length of stay (LOS). Patient group and other factors that may have influenced PACU-LOS were examined using time-to-event analysis. The raw PACU-LOS was not shown to be different between the two groups (log rank test, P=0.12). Covariate adjusted estimates were used to compare the two discharge criteria and also to identify other factors influencing PACU-LOS. The Cox regression model was poorly specified and a log-logistic accelerated failure time model was found to be the most parsimonious predictive model.

Predictors of decreased PACU-LOS were the treatment group (Group 2 versus Group 1) and the covariate recording anaesthetic airway choice (no endotracheal tube (ETT) versus ETT). Surgical time, as a linear function, intra- and postoperative opioid administration, as well as postoperative antiemetic use were predictors of increased PACU-LOS. Patient age, gender, urgency of surgery, and ASA classification were not predictive of PACU-LOS. Using covariate adjusted estimates, the new PACU discharge criteria, based on the Aldrete's scoring system, was associated with a significantly reduced PACU-LOS in comparison with time-based criteria.

Hearing Trajectory in Children with Congenital Cytomegalovirus Infection

Objectives To compare hearing trajectories among children with symptomatic and asymptomatic congenital cytomegalovirus infection through age 18 years and to identify brain abnormalities associated with sensorineural hearing loss (SNHL) in asymptomatic case patients. Study Design Longitudinal prospective cohort study. Setting Tertiary medical center. Subjects and Methods The study included 96 case patients (4 symptomatic and 92 asymptomatic) identified through hospital-based newborn cytomegalovirus screening from 1982 to 1992 and 72 symptomatic case patients identified through referrals from 1993 to 2005. We used growth curve modeling to analyze hearing thresholds (0.5-8 kHz) by ear with increasing age and Cox regression to determine abnormal findings on head computed tomography scan associated with SNHL (hearing threshold ≥25 dB in any audiometric frequency) among asymptomatic case patients. Results Fifty-six (74%) symptomatic and 20 (22%) asymptomatic case patients had SNHL: congenital/early-onset SNHL was diagnosed in 78 (51%) and 10 (5%) ears, respectively, and delayed-onset SNHL in 25 (17%) and 20 (11%) ears; 49 (32%) and 154 (84%) ears had normal hearing. In affected ears, all frequency-specific hearing thresholds worsened with age. Congenital/early-onset SNHL was significantly worse (severe-profound range, >70 dB) than delayed-onset SNHL (mild-moderate range, 26-55 db). Frequency-specific hearing thresholds were significantly different between symptomatic and asymptomatic case patients at 0.5 to 1 kHz but not at higher frequencies (2-8 kHz). Among asymptomatic case patients, white matter lucency was significantly associated with SNHL by age 5 years (hazard ratio, 4.4; 95% CI, 1.3-15.6). Conclusion Congenital/early-onset SNHL frequently resulted in severe to profound loss in symptomatic and asymptomatic case patients. White matter lucency in asymptomatic case patients was significantly associated with SNHL by age 5 years.

Hearing Loss in Children With Asymptomatic Congenital Cytomegalovirus Infection

OBJECTIVES

To assess the prevalence, characteristics, and risk of sensorineural hearing loss (SNHL) in children with congenital cytomegalovirus infection identified through hospital-based newborn screening who were asymptomatic at birth compared with uninfected children.

METHODS

We included 92 case-patients and 51 controls assessed by using auditory brainstem response and behavioral audiometry. We used Kaplan-Meier survival analysis to estimate the prevalence of SNHL, defined as ≥25 dB hearing level at any frequency and Cox proportional hazards regression analyses to compare SNHL risk between groups.

RESULTS

At age 18 years, SNHL prevalence was 25% (95% confidence interval [CI]: 17%-36%) among case-patients and 8% (95% CI: 3%-22%) in controls (hazard ratio [HR]: 4.0; 95% CI: 1.2-14.5; P = .02). Among children without SNHL by age 5 years, the risk of delayed-onset SNHL was not significantly greater for case-patients than for controls (HR: 1.6; 95% CI: 0.4-6.1; P = .5). Among case-patients, the risk of delayed-onset SNHL was significantly greater among those with unilateral congenital/early-onset hearing loss than those without (HR: 6.9; 95% CI: 2.5-19.1; P < .01). The prevalence of severe to profound bilateral SNHL among case-patients was 2% (95% CI: 1%-9%).

CONCLUSIONS

Delayed-onset and progression of SNHL among children with asymptomatic congenital cytomegalovirus infection continued to occur throughout adolescence. However, the risk of developing SNHL after age 5 years among case-patients was not different than in uninfected children. Overall, 2% of case-patients developed SNHL that was severe enough for them to be candidates for cochlear implantation.

Peripheral nerve stimulation for the treatment of chronic pain

The aim of this retrospective study is to evaluate the role of the implanted peripheral nerve stimulator in patients with pain in a peripheral nerve distribution. The current study is the largest in the literature that examines the role of the implantable peripheral nerve stimulator in the chronic pain patient. Our patient sample included 38 patients (with 41 nerve stimulators), consisting of 19 males and 19 females with a mean age of 44 years (SD=11 years). Four groups of etiologic factors were identified; blunt or sharp nerve trauma (14/38), iatrogenic injuries from surgery (9/38), inadvertent injection of a nerve (9/38) and post surgery for entrapment or tumour (8/38). Stimulation was attempted in 45 patients, but an initial trial failed in 4. Mean follow-up time from implantation of the stimulator was 31 months (SD=19 months). Compensation benefit was an issue in 29 cases (76%). Outcome following implantation was assessed based on pain criteria, narcotic usage and return to normal function/ work. Relief from preoperative pain was judged as good (>50% relief) by 23/38 patients (61%). A total of 15 patients reported fair or poor results (39%). Six patients required removal of their stimulators (15%) due to infection or reduction of pain control after an initial good result. A statistically significant decrease in reported pain level was found postoperatively (p<0.05). Workers' compensation patients have equivalent outcomes to non-compensable patients (p>0.05). Eighteen of 38 (47%) patients reported a significant improvement in their activity levels following stimulator implant. In conclusion, over 60% of patients had a significant improvement in their pain and lifestyle following implantation of peripheral nerve stimulators. We therefore conclude that peripheral nerve stimulation can be useful in decreasing pain in well selected patients with severe pain in the distribution of a peripheral nerve.

Translation molekularer Zusammenhänge in die klinische Anwendung

For patients with metastatic renal cell cancer (RCC), therapeutic options after cytokine failure are rather limited. There is a considerable need to identify new substances for systemic therapy. Due to upregulation after the loss of a functional von Hippel Lindau gene product, the vascular endothelial growth factor (VEGF) pathway is a promising target for a molecular based therapy. Over the last few years, therapeutic agents have been developed which inhibit this pathway at various levels. Here, we provide an overview of the molecular background and currently used drugs which have entered clinical trials in the setting of metastatic RCC disease. Until now, the results from early clinical trials are very promising, however, the best schedule, dosage, potential combination regimens, as well as long time efficacy, are still to be determined.

Barriers to effective perioperative communication in indigenous Australians: an audit of progress since 1996

This prospective study was designed to elucidate barriers limiting effective perioperative communication between indigenous Australians and anaesthetists, and to identify strategies for improving communication. A questionnaire was used to collect data on 1040 consecutive patients undergoing anaesthesia at Royal Darwin Hospital between February and March 2003. 27.1% of these patients described themselves as Aboriginal. Aboriginal patients were more likely to undergo emergency surgery and were more likely to be classified as ASA 3, 4 or 5 than non-indigenous patients. Communication difficulties were identified in 28.7% of all Aboriginal patients, which was 31 times higher than those in non-Aboriginal patients. The most common reason identified for this was difficulty in speaking English. Only 17.7% of Aboriginal patients presenting to the operating theatre spoke English as their first language. Unfortunately, the anaesthetic team utilized the Aboriginal interpreter service in only a minority of cases. Communication difficulty in indigenous Australians is pervasive and often goes unrecognized. The results suggest that heath care providers may need staff training in cross-cultural communication and that protocols need to be developed within the health care system so that interpreters are called upon automatically early in the admission process.

Treatment of painful peripheral neuroma by vein implantation

Painful neuromas form on cutaneous nerves as a result of trauma, pressure, stretch or entrapment. Since the earliest descriptions of neuromas, proposed treatments have been met with poor results and controversy. The myriad of treatments described include: simple division of an affected nerve, implantation into muscle or bone, silicon sleeves and caps, repeated injection of steroids, end-to-side neurorrhaphy, medication and vein caps to name a few. Due to encouraging recent reports of treatment of painful neuromas by vein implantation, the authors describe a simple technique to achieve this surgical goal. As veins are readily accessible due to their proximity in the neurovascular bundle, they serve as a ready source for grafting. The advantages include minimisation of trauma to bone and muscle as compared with previous treatment techniques and the relative ease of the method.

Posterior femoral cutaneous nerve entrapment neuropathy: operative exposure and technique

An isolated posterior femoral cutaneous nerve lesion is rare. There have been seven reported cases to date. We report a 51-year-old male with pain in the posterolateral thigh, atypical from the classic anatomical description. Somatosensory evoked potentials were suggestive of a posterior femoral cutaneous nerve lesion. We describe our operative exposure and technique for decompression of the posterior femoral cutaneous nerve and include a comparative anatomical explanation for the unusual area of our patient's pain.

Extremely low vertical-emittance beam in the accelerator test facility at KEK

Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping ring which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than 1% of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than 2.8 x 10(-8) rad m at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance.

Secreted euryarchaeal microhalocins kill hyperthermophilic crenarchaea

Few antibiotics targeting members of the archaeal domain are currently available for genetic studies. Since bacterial antibiotics are frequently directed against competing and related organisms, archaea by analogy might produce effective antiarchaeal antibiotics. Peptide antibiotic (halocin) preparations from euryarchaeal halophilic strains S8a, GN101, and TuA4 were found to be toxic for members of the hyperthermophilic crenarchaeal genus Sulfolobus. No toxicity was evident against representative bacteria or eukarya. Halocin S8 (strain S8a) and halocin R1 (strain GN101) preparations were cytostatic, while halocin A4 (strain TuA4) preparations were cytocidal. Subsequent studies focused on the use of halocin A4 preparations and Sulfolobus solfataricus. Strain TuA4 cell lysates were not toxic for S. solfataricus, and protease (but not nuclease) treatment of the halocin A4 preparation inactivated toxicity, indicating that the A4 toxic factor must be a secreted protein. Potassium chloride supplementation of the Sulfolobus assay medium potentiated toxicity, implicating use of a salt-dependent mechanism. The utility of halocin A4 preparations for genetic manipulation of S. solfataricus was assessed through the isolation of UV-induced resistant mutants. The mutants exhibited stable phenotypes and were placed into distinct classes based on their levels of resistance.

Quercetin cumulatively enhances copper induction of metallothionein in intestinal cells

Wilson's disease, a genetic copper-overload condition, is currently treated with zinc because of the ability of zinc to induce metallothionein. We are interested in nonmetal chemicals that may alter intestinal copper metabolism and thus help to alleviate copper toxicity. Previously, we have shown that quercetin, a dietary flavonoid, can chelate copper. This study further examined the interaction of quercetin and copper in intestinal epithelial cells. We found that quercetin enhanced metallothoinein induction by copper and the effect was dose dependent. Quercetin also exerted a cumulative effect after repeated exposure. Repeated low-dose treatment (3-10 microM) of cells with quercetin can lead to the same effect on metallothoinein as one higher concentration treatment (100 microM). This property of quercetin is distinct from its chemical interaction with copper, but both can contribute to a reduction of copper toxicity. Among other flavonoids tested, two other copper chelators, catechin and rutin, did not increase copper induction of metallothionein, whereas genistein, an isoflavone that does not interact with copper chemically, increased copper induction of metallothionein. The effect of quercetin on copper metabolism is unique. Quercetin decreased zinc-stimulated metallothionein expression and had no effect on the cadmium induction of metallothionein. The clinical application of our observation needs to be explored.

Autohydrolysis of plant polysaccharides using transgenic hyperthermophilic enzymes

Commercial bioprocessing of plant carbohydrates, such as starch or cellulose, necessitates the use of commodity enzyme additives to accelerate polysaccharide hydrolysis. To simplify this procedure, transgenic plant tissues constitutively producing commodity enzymes were examined as a strategy for accelerating carbohydrate bioprocessing. Hyperthermophilic glycosyl hydrolases were selected to circumvent enzyme toxicity, because such enzymes are inactive at plant growth temperatures and are therefore physiologically benign. Transgenic tobacco lines were established that produced either a hyperthermophilic alpha-glucosidase or a beta-glycosidase using genes derived from the archaeon Sulfolobus solfataricus. Western blot and immunoprecipitation analyses were used to demonstrate the presence of recombinant enzymes in plant tissues. Transgenic enzyme levels exhibited an unusual delayed pattern of accumulation while their activities survived plant tissue preservation. Transgenic plant protein extracts released glucose from purified polysaccharide substrates at appreciable rates during incubation in high-temperature reactions. Glucose was also produced following enzymatic treatment of plant extracts enriched for endogenous polysaccharides. Direct conversion of plant tissue into free sugar was evident using whole plant extracts of either transgenic line, and could be significantly accelerated in a synergistic manner by combining transgenic line extracts.

Bacterial growth state distinguished by single-cell protein profiling: does chlorination kill coliforms in municipal effluent?

Municipal effluent is the largest reservoir of human enteric bacteria. Its public health significance, however, depends upon the physiological status of the wastewater bacterial community. A novel immunofluorescence assay was developed and used to examine the bacterial growth state during wastewater disinfection. Quantitative levels of three highly conserved cytosolic proteins (DnaK, Dps, and Fis) were determined by using enterobacterium-specific antibody fluorochrome-coupled probes. Enterobacterial Fis homologs were abundant in growing cells and nearly undetectable in stationary-phase cells. In contrast, enterobacterial Dps homologs were abundant in stationary-phase cells but virtually undetectable in growing cells. The range of variation in the abundance of both proteins was at least 100-fold as determined by Western blotting and immunofluorescence analysis. Enterobacterial DnaK homologs were nearly invariant with growth state, enabling their use as permeabilization controls. The cellular growth states of individual enterobacteria in wastewater samples were determined by measurement of Fis, Dps, and DnaK abundance (protein profiling). Intermediate levels of Fis and Dps were evident and occurred in response to physiological transitions. The results indicate that chlorination failed to kill coliforms but rather elicited nutrient starvation and a reversible nonculturable state. These studies suggest that the current standard procedures for wastewater analysis which rely on detection of culturable cells likely underestimate fecal coliform content.

Extragenic pleiotropic mutations that repress glycosyl hydrolase expression in the hyperthermophilic archaeon Sulfolobus solfataricus

The hyperthermophilic archaeon Sulfolobus solfataricus employs a catabolite repression-like regulatory system to control enzymes involved in carbon and energy metabolism. To better understand the basis of this system, spontaneous glycosyl hydrolase mutants were isolated using a genetic screen for mutations, which reduced expression of the lacS gene. The specific activities of three glycosyl hydrolases, including an alpha-glucosidase (malA), a beta-glycosidase (lacS), and the major secreted alpha-amylase, were measured in the mutant strains using enzyme activity assays, Western blot analysis, and Northern blot analysis. On the basis of these results the mutants were divided into two classes. Group I mutants exhibited a pleiotropic defect in glycosyl hydrolase expression, while a single group II mutant was altered only in lacS expression. PCR, Southern blot analysis, comparative heterologous expression in Escherichia coli, and DNA sequence analysis excluded cis-acting mutations as the explanation for reduced lacS expression in group I mutants. In contrast lacS and flanking sequences were deleted in the group II mutant. Revertants were isolated from group I mutants using a lacS-specific screen and selection. These revertants were pleiotropic and restored glycosyl hydrolase activity either partially or completely to wild-type levels as indicated by enzyme assays and Western blots. The lacS mutation in the group II mutant, however, was nonrevertible. The existence of group I mutants and their revertants reveals the presence of a trans-acting transcriptional regulatory system for glycosyl hydrolase expression.

Coordinate transcriptional control in the hyperthermophilic archaeon Sulfolobus solfataricus

The existence of a global gene regulatory system in the hyperthermophilic archaeon Sulfolobus solfataricus is described. The system is responsive to carbon source quality and acts at the level of transcription to coordinate synthesis of three physically unlinked glycosyl hydrolases implicated in carbohydrate utilization. The specific activities of three enzymes, an alpha-glucosidase (malA), a beta-glycosidase (lacS), and an alpha-amylase, were reduced 4-, 20-, and 10-fold, respectively, in response to the addition of supplementary carbon sources to a minimal sucrose medium. Western blot analysis using anti-alpha-glucosidase and anti-beta-glycosidase antibodies indicated that reduced enzyme activities resulted exclusively from decreased enzyme levels. Northern blot analysis of malA and lacS mRNAs revealed that changes in enzyme abundance arose primarily from reductions in transcript concentrations. Culture conditions precipitating rapid changes in lacS gene expression were established to determine the response time of the regulatory system in vivo. Full induction occurred within a single generation whereas full repression occurred more slowly, requiring nearly 38 generations. Since lacS mRNA abundance changed much more rapidly in response to a nutrient down shift than to a nutrient up shift, transcript synthesis rather than degradation likely plays a role in the regulatory response.

Polypeptide flux through bacterial Hsp70: DnaK cooperates with trigger factor in chaperoning nascent chains

A role for DnaK, the major E. coli Hsp70, in chaperoning de novo protein folding has remained elusive. Here we show that under nonstress conditions DnaK transiently associates with a wide variety of nascent and newly synthesized polypeptides, with a preference for chains larger than 30 kDa. Deletion of the nonessential gene encoding trigger factor, a ribosome-associated chaperone, results in a doubling of the fraction of nascent polypeptides interacting with DnaK. Combined deletion of the trigger factor and DnaK genes is lethal under normal growth conditions. These findings indicate important, partially overlapping functions of DnaK and trigger factor in de novo protein folding and explain why the loss of either chaperone can be tolerated by E. coli.

Molecular characterization of the alpha-glucosidase gene (malA) from the hyperthermophilic archaeon Sulfolobus solfataricus

Acidic hot springs are colonized by a diversity of hyperthermophilic organisms requiring extremes of temperature and pH for growth. To clarify how carbohydrates are consumed in such locations, the structural gene (malA) encoding the major soluble alpha-glucosidase (maltase) and flanking sequences from Sulfolobus solfataricus were cloned and characterized. This is the first report of an alpha-glucosidase gene from the archaeal domain. malA is 2,083 bp and encodes a protein of 693 amino acids with a calculated mass of 80.5 kDa. It is flanked on the 5' side by an unusual 1-kb intergenic region. Northern blot analysis of the malA region identified transcripts for malA and an upstream open reading frame located 5' to the 1-kb intergenic region. The malA transcription start site was located by primer extension analysis to a guanine residue 8 bp 5' of the malA start codon. Gel mobility shift analysis of the malA promoter region suggests that sequences 3' to position -33, including a consensus archaeal TATA box, play an essential role in malA expression. malA homologs were detected by Southern blot analysis in other S. solfataricus strains and in Sulfolobus shibatae, while no homologs were evident in Sulfolobus acidocaldarius, lending further support to the proposed revision of the genus Sulfolobus. Phylogenetic analyses indicate that the closest S. solfataricus alpha-glucosidase homologs are of mammalian origin. Characterization of the recombinant enzyme purified from Escherichia coli revealed differences from the natural enzyme in thermostability and electrophoretic behavior. Glycogen is a substrate for the recombinant enzyme. Unlike maltose hydrolysis, glycogen hydrolysis is optimal at the intracellular pH of the organism. These results indicate a unique role for the S. solfataricus alpha-glucosidase in carbohydrate metabolism.

Roles of DnaK and RpoS in starvation-induced thermotolerance of Escherichia coli

DnaK is essential for starvation-induced resistance to heat, oxidation, and reductive division in Escherichia coli. Studies reported here indicate that DnaK is also required for starvation-induced osmotolerance, catalase activity, and the production of the RpoS-controlled Dps (PexB) protein. Because these dnaK mutant phenotypes closely resemble those of rpoS (sigma38) mutants, the relationship between DnaK and RpoS was evaluated directly during growth and starvation at 30 degrees C in strains with genetically altered DnaK content. A starvation-specific effect of DnaK on RpoS abundance was observed. During carbon starvation, DnaK deficiency reduced RpoS levels threefold, while DnaK excess increased RpoS levels nearly twofold. Complementation of the dnaK mutation restored starvation-induced RpoS levels to normal. RpoS deficiency had no effect on the cellular concentration of DnaK, revealing an epistatic relationship between DnaK and RpoS. Protein half-life studies conducted at the onset of starvation indicate that DnaK deficiency significantly destabilized RpoS. RpoH (sigma32) suppressors of the dnaK mutant with restored levels of RpoS and dnaK rpoS double mutants were used to show that DnaK plays both an independent and an RpoS-dependent role in starvation-induced thermotolerance. The results suggest that DnaK coordinates sigma factor levels in glucose-starved E. coli.

Maxillary sinus augmentation using different grafting materials and osseointegrated dental implants in monkeys. Part II. Evaluation of porous hydroxyapatite as a grafting material

The aim of this study was to evaluate clinically, histologically and histometrically the use of porous hydroxyapatite (i.e. Interpore-200) as a bone grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (i.e. Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted and the remaining bone between the alveolar crest and the bottom of the sinus was reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed on one side of the jaws in each monkey, and the sinuses grafted with the porous hydroxyapatite. Two IMZ titanium plasma-sprayed cylinder implants were then immediately placed into the augmented sinus (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed implants-loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice). The contralateral side of each monkey received the same treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants-unloaded group and delayed implants-unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologic analysis demonstrated a significant amount of new bone formation in the augmented sinuses. Porous hydroxyapatite graft particles appeared to be integrated to the new bone. The percentage of direct mineralized bone-to-implant contact in the augmented area was greater on the delayed-placed implants than on the simultaneously-placed implants. Also, the percentage of direct mineralized bone-to-implant contact was greater in the residual bone than in the augmented area. It was concluded that this porous hydroxyapatite bone graft enhanced bone formation and bone-to-implant contact in the augmented sinuses and that the delayed implant placement in combination with the sinus augmentation procedure appears to result in a higher percentage of direct mineralized bone-to-implant contact.

Whole-limb irradiation of the lower calf using a six-field electron technique

The present work demonstrates utilization of electron beam irradiation for the treatment of Kaposi's sarcoma when the full circumference of the lower calf is involved, and when the deep lymphatics are negative for disease. The finite penetration of the electron beam spares deep tissue, preventing the edema associated with photon total limb irradiation. The number of fields with fall-off required to produce a uniform dose to a cylindrical anatomic structure was studied by calculating dose distributions resulting from two-, four-, and six-field techniques for a 5-MeV electron beam and a 9 cm diameter cylinder. The dosimetry and set-up for the six-field technique is demonstrated by a case study. Results show that a six-field electron technique produced a sufficiently uniform dose while remaining relatively easy to set up and use to deliver patient treatment. For the patient case study, dose distributions for the six-field technique showed that (1) the penetration of the 90% dose decreased from 1.5 cm for a single field to approximately 1.0 cm for a 5-MeV beam; (2) the surface dose increased from approximately 70% to 100%, (3) the dose around the circumference of the leg at the depth of 1 cm or less varied from approximately 90% to 120% of the prescribed dose; and (4) the prescribed dose was 2.5 times the maximum central-axis dose from a single field. The six-field treatment was relatively simple to apply and produced an acceptable dose distribution for treatment of Kaposi's sarcoma of the lower calf. This treatment should be applicable to other sites such as the thigh and arms and for other cutaneous diseases such as melanoma.

The glucose effect and regulation of alpha-amylase synthesis in the hyperthermophilic archaeon Sulfolobus solfataricus

An alpha-amylase was purified from culture supernatants of Sulfolobus solfataricus 98/2 during growth on starch as the sole carbon and energy source. The enzyme is a homodimer with a subunit mass of 120 kDa. It catalyzes the hydrolysis of starch, dextrin, and alpha-cyclodextrin with similar efficiencies. Addition of exogenous glucose represses production of alpha-amylase, demonstrating that a classical glucose effect is operative in this organism. Synthesis of [35S]-alpha-amylase protein is also subject to the glucose effect. alpha-Amylase is constitutively produced at low levels but can be induced further by starch addition. The absolute levels of alpha-amylase detected in culture supernatants varied greatly with the type of sole carbon source used to support growth. Aspartate was identified as the most repressing sole carbon source for alpha-amylase production, while glutamate was the most derepressing. The pattern of regulation of alpha-amylase production seen in this organism indicates that a catabolite repression-like system is present in a member of the archaea.

Multicopy plasmid suppression of stationary phase chaperone toxicity in Escherichia coli by phosphogluconate dehydratase and the N-terminus of DnaK

Overproduction of DnaK in Escherichia coli results in a bacteriocidal effect. This effect is most acute in stationary phase cells. A selection scheme was developed to isolate multicopy suppressors from an E. coli plasmid expression library, which overcome the stationary phase toxicity of excess DnaK. Two suppressor plasmids were recovered which contained inserts of 1.85 kb and 2.69 kb, respectively. Rearranged and deleted plasmid derivatives were constructed and used to further localize the suppressors. DNA sequence analysis demonstrated that one suppressor encoded phosphogluconate dehydratase (Edd) while the other suppressor encoded the N-terminal 237 amino acids of DnaK itself (DnaK'). Strains bearing the suppressor plasmids constitutively overproduced proteins with apparent masses of 66 kDa (Edd) and 37 kDa (DnaK') as determined by gel electrophoresis. Western blot analysis using polyclonal antisera specific for either Edd or DnaK confirmed the identity of these overproduced proteins. Suppression of DnaK toxicity was eliminated by the introduction of a + 1 frameshift mutation early in the respective coding regions of either of the two suppressors. These results suggest that suppressor gene translation plays a role in the mechanism of DnaK suppression.

The role of anion channels in osmotically activated taurine release from embryonic skate (Raja eglanteria) heart

Taurine, a major osmolyte of vertebrate hearts, is released from the skate heart at increased rates during hypotonic stress. We tested the hypothesis that this taurine release is mediated by chloride channels activated by swelling. Two inhibitors of the channels, NPPB and DIDS, inhibited the volume-activated release of taurine from embryonic skate hearts. These results support the hypothesis that swelling-activated chloride channels mediate the release of cardiac taurine.

Lung tumor cells: a multivariate approach to cell classification using two-dimensional protein pattern

High resolution two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) is a powerful research tool for the analytical separation of cellular proteins. The qualitative and quantitative pattern of polypeptides synthesized by a cell represents its phenotype and thus defines characteristics such as the morphology and the biological behavior of the cell. By analyzing and comparing the protein patterns of different cells it is possible to recognize the cell type and also to identify the most typical features of these cells. In applied pathology it is often difficult to identify the tissue of origin and the stage or grade of a neoplasia by cellular morphology analyzed by classical or immunostaining procedures. The protein pattern itself is the most characteristic feature of a cell and should therefore contribute to the identification of the cell type. For this reason we separated protein fractions originating from different lung tumor cell lines using 2-D PAGE and we compared the resulting patterns on a multivariate statistical level using correspondence analysis (CA) and ascendant hierarchical clustering (AHC). The results indicate that (i) protein patterns are highly typical for cells and that (ii) the comparison of the protein patterns of a set of interesting cell types allows the identification of potentially new marker proteins. 2-D PAGE is thus a unique and powerful tool for molecular cytology or histopathology, unveiling the protein expression level of tissues or cells.

An essential role for the Escherichia coli DnaK protein in starvation-induced thermotolerance, H2O2 resistance, and reductive division

During a 3-day period, glucose starvation of wild-type Escherichia coli produced thermotolerant, H2O2-resistant, small cells with a round morphology. These cells contained elevated levels of the DnaK protein, adjusted either for total protein or on a per-cell basis. Immunoprecipitation of [35S]methionine-labeled protein produced by such starving cells demonstrated that DnaK underwent continuous synthesis but at decreasing rates throughout this time. Glucose resupplementation of starving cells resulted in rapid loss of thermotolerance, H2O2 resistance, and the elevated DnaK levels. A dnaK deletion mutant, but not an otherwise isogenic wild-type strain, failed to develop starvation-induced thermotolerance or H2O2 resistance. The filamentous phenotype associated with DnaK deficiency was suppressed by cultivation in a defined glucose medium. When starved for glucose, the nonfilamentous and rod-shaped dnaK mutant strain failed to convert into the small spherical form typical of starving wild-type cells. The dnaK mutant retained the ability to develop adaptive H2O2 resistance during growth but not adaptive resistance to heat. Complementation of DnaK deficiency by using Ptac-regulated dnaK+ and dnaK+J+ expression plasmids confirmed a specific role for the DnaK molecular chaperone in these starvation-induced phenotypes.

[Reporting occupational disease. A system ready for revision]

The article reviews the system of reporting occupational disease and the reporting pattern over the last ten years. The available information seems to indicate a very low reported incidence of occupational disease. Possible reasons are given. There seems to be a need to simplify our present system and make it more user-friendly. There is also a general need to inform and motivate various user groups, especially general practitioners. In addition, greater collaboration between occupational and public health services may help to increase the reporting of occupational disease in Norway.

Purification and characterization of a maltase from the extremely thermophilic crenarchaeote Sulfolobus solfataricus

A soluble maltase (alpha-glucosidase) with an apparent subunit mass of 80 kDa was purified to homogeneity from Sulfolobus solfataricus. The enzyme liberates glucose from maltose and malto-oligomers. Maximal activity was observed at 105 degrees C, with half-lives of 11 h (85 degrees C), 3.0 h (95 degrees C), and 2.75 h (100 degrees C). The enzyme was generally resistant to proteolysis and denaturants including aliphatic alcohols. n-Propanol treatment at 85 degrees C increased both Km and Vmax for maltose hydrolysis.

Monoclonal antibody recognition and function of a DnaK (HSP70) epitope found in gram-negative bacteria

The isolation and characterization of a monoclonal antibody (MAb 2G5) specific for the bacterial DnaK (HSP70) protein is described. The 2G5 MAb was initially selected because of its ability to bind to DnaK under denaturing conditions. Isotype analyses indicated that 2G5 was an immunoglobulin G2a. Dose-response Western blot (immunoblot) experiments with purified but unconcentrated 2G5 permitted detection of 10 ng of pure DnaK protein. The DnaK epitope was determined by Western blot analysis of a series of truncated DnaK fragments overproduced in Escherichia coli using 5' and 3' dnaK-deleted expression plasmids. The epitope mapped to a 22-amino-acid region spanning DnaK residues 288 and 310. Phylogenetic distribution of the epitope was examined by Western blot analysis of a wide variety of bacterial species and indicated that the epitope was uniquely present in gram-negative organisms. The proximity of the epitope to the presumed DnaK ATP-binding pocket suggested that MAb binding might inhibit DnaK ATPase activity. In vitro analysis supported this prediction and demonstrated that MAb-mediated inhibition of ATPase activity was antibody specific and occurred at stoichiometric molar ratios of MAb to DnaK. Possible mechanisms to explain the ability of the 2G5 MAb to inhibit DnaK activity are discussed.

Nucleotide sequence analysis and heterologous expression of the Erysipelothrix rhusiopathiae dnaJ gene

DNA sequence analysis of chromosomal DNA from the Gram-positive facultative intracellular pathogen, Erysipelothrix rhusiopathiae has identified a dnaJ heat shock gene homolog. A 1109-bp open reading frame encoding dnaJ is located immediately 3' to the E. rhusiopathiae dnaK gene. The deduced DnaJ amino acid sequence exhibits the modular structure of other members of the DnaJ protein class including a glycine-rich region and the repeating consensus sequence CXXCXGXGX. Heterologous expression of the dnaJ sequence in Escherichia coli resulted in accumulation of a unique 38.9-kDa protein with an isoelectric point of 8.0. Deletion analysis of the dnaJ gene was used to confirm that the overproduced protein was encoded by the dnaJ sequence.

Cloning, heterologous expression, and characterization of the Erysipelothrix rhusiopathiae DnaK protein

The dnaK (hsp70) gene from the facultative intracellular pathogen Erysipelothrix rhusiopathiae was cloned by heterologous DNA hybridization of a genomic library using the Escherichia coli dnaK gene as a probe. A 3.2-kb fragment which encoded an 1,800-bp open reading frame was recovered. The deduced amino acid sequence of this open reading frame shares 56% identity with the E. coli DnaK protein. Expression of the encoded protein in E. coli by using the phage T7 promoter/polymerase system resulted in accumulation of a unique 65-kDa protein. Western blot (immunoblot) analysis of extracts from a recombinant E. coli strain using anti-E. coli DnaK polyclonal antibodies confirmed that the cloned gene encodes a DnaK homolog. The recombinant E. rhusiopathiae DnaK protein was purified to 80% homogeneity by ATP affinity chromatography. The purified material hydrolyzed ATP with a specific activity of 100 nmol min-1 mg of protein-1. Analysis of total protein extracts from E. rhusiopathiae indicates that DnaK is a highly expressed protein in this organism.

Vasopressin receptors in adrenal cortex of sheep: does autoradiography indicate an irreversible binding of the ligand?

Tritiated arginine vasopressin ([3H]-AVP) labelled specific loci of murine renal medulla and ovine adrenal cortex in thin sections of an autoradiographic experiment. The label was fully displaced by 2 x 10(-6) M cold ligand in the case of renal, but not of adrenal sections. 10 and 100 microM AVP, however, partially displaced the radioactivity also from labelled adrenal sections. At room temperature, the half maximal blackening of the film occurred at a concentration of 26 +/- 0.9 microM. In binding experiments employing AVP and adrenocortical cell membranes, the model assuming two saturable binding sites yielded a significantly better fit than the one-site model. The equilibrium dissociation constants of ice-cold membrane preparations were 8.67 nmol/l for the high affinity site and 3.16 mumol/l for the low affinity binding site. It is concluded that the low affinity binding is governed by laws of chemical equilibrium, rather than by surface adsorption or similar "nonspecific" phenomena. When such low affinity sites are present in a tissue, higher concentrations of cold ligand ought to be used before a nondisplaceable binding is ascribed as "non-specific" or "irreversible".

Physiological consequences of DnaK and DnaJ overproduction in Escherichia coli

The physiological consequences of molecular chaperone overproduction in Escherichia coli are presented. Constitutive overproduction of DnaK from a multicopy plasmid containing large chromosomal fragments spanning the dnaK region resulted in plasmid instability. Co-overproduction of DnaJ with DnaK stabilized plasmid levels. To examine the effects of altered levels of DnaK and DnaJ in a more specific manner, an inducible expression system for dnaK and dnaJ was constructed and characterized. Differential rates of DnaK synthesis were determined by quantitative Western blot (immunoblot) analysis. Moderate levels of DnaK overproduction resulted in a defect in cell septation and formation of cell filaments, but co-overproduction of DnaJ overcame this effect. Further increases in the level of DnaK terminated culture growth despite increased levels of DnaJ. DnaK overproduction was found to be bacteriocidal, and this effect was also partially suppressed by DnaJ. The bacteriocidal effect was apparent only with cultures which were allowed to enter stationary phase, indicating that DnaK toxicity is growth phase dependent.

DnaK-Mediated Alterations in Human Growth Hormone Protein Inclusion Bodies

Protein overproduction in microbes frequently results in protein misfolding and aggregation though the molecular basis for this process is unclear. The HSP70 chaperonin, DnaK, was identified as an important factor controlling heterologous protein aggregation in Escherichia coli. Co-overproduction of DnaK significantly reduced human growth hormone (HGH) protein inclusion body formation and the extent of HGH aggregation.

Stiff-person syndrome: an autoimmune disease

Stiff-person syndrome (SPS) is characterized by progressive, usually symmetric rigidity of the axial muscles with superimposed painful spasms precipitated by tactile stimuli, passive stretch, volitional movement of affected or unaffected muscles, startling noises, and emotional stimuli. Electromyography demonstrates continuous normal motor unit potentials in the affected muscles. Both the rigidity and the spasms are relieved by sleep, general anesthesia, myoneural blockade, peripheral nerve blockade, and partially by diazepam. Evidence for an autoimmune etiology of SPS includes its association with other autoimmune diseases and autoantibodies and the presence of antibodies against glutamic acid decarboxylase (GAD) in the cerebrospinal fluid (CSF) of many affected patients. We describe two patients with this syndrome who had GAD antibodies in both CSF and serum. Partial relief of the symptoms in these patients by corticosteroid therapy provides additional evidence of an autoimmune etiology of SPS and of the role of immunotherapy in its treatment.