The Association of Clinical Characteristics and Tumour Markers With Image-Defined Risk Factors in the Management of Neuroblastoma in South Africa

AIMS

Image-defined risk factors (IDRFs) in neuroblastoma predict surgical complications and management outcomes. As there is a lack of data regarding the association of IDRFs with clinical and pathological factors, this study evaluated the prognostic value of IDRFs to predict neuroblastoma survival outcomes.

MATERIALS AND METHODS

This was a retrospective study including 345 patients and reviewed diagnostic imaging for 20 IDRFs, pleural effusions and ascites. The IDRFs were grouped into five 'primary IDRFs' cohorts with vascular encasement, involvement of multiple body compartments, organ infiltration, airway obstruction and intraspinal extension. The association between clinical, histopathological and biological characteristics of neuroblastoma and management was evaluated.

RESULTS

More patients without IDRFs had operations compared with patients with IDRFs, with a trend towards significance (64.4% versus 35.6%, P = 0.082). Patients with multiple compartment tumour involvement (P = 0.003) and organ infiltration (P < 0.001) had a higher risk of surgical complications. The 5-year overall survival of the group with more than one IDRF was 0.0% and those with pleural effusions or ascites 6.7%, associated with the worst outcome (P = 0.005). The total number of IDRFs was not predictive of the metastatic remission rate (P = 0.585) or overall survival (P = 0.142), with no conclusive association found between IDRF groups and clinical or biological markers.

CONCLUSIONS

Patients with more than one IDRF had the shortest survival time, whereas those with pleural effusions and ascites at diagnosis had a poor outcome. Standardised reporting of IDRFs is crucial for predicting prognosis.

The Association between Tumour Markers and Meta-iodobenzylguanidine Scans in South African Children with High-risk Neuroblastoma

AIMS

Diagnostic and post-induction ¹²³I-meta-iodobenzylguanidine (¹²³I-mIBG) scans have prognostic significance in the treatment of neuroblastoma, but data from low- and middle-income countries are limited due to resource constraints. The aim of this study was to determine the association between neuroblastoma-associated tumour markers (lactate dehydrogenase [LDH], ferritin and MYCN amplification) and ¹²³I-mIBG scans (modified Curie scores and metastatic disease patterns) in predicting complete metastatic response rates (mCR) and overall survival.

MATERIALS AND METHODS

Two hundred and ninety patients diagnosed with high-risk neuroblastoma in South Africa between January 2000 and May 2018 and a subanalysis of 78 patients with diagnostic ¹²³I-mIBG scans were included. Data collection included LDH, ferritin and MYCN amplification at diagnosis. Two nuclear physicians independently determined the modified Curie scores and pattern of distribution for each diagnostic and post-induction ¹²³I-mIBG scans with high inter-rater agreement (r = 0.952) and reliability (K = 0.805). The cut-off values for the diagnostic and post-induction modified Curie scores of ≥7.0 (P = 0.026) and 3 (P = 0.009), respectively, were generated. The association between the tumour markers and the modified Curie score of the ¹²³I-mIBG scans was determined using post-induction mCR and 2-year overall survival.

RESULTS

Diagnostic LDH (P < 0.001), ferritin (P < 0.001) and the diagnostic modified Curie scores (P = 0.019) significantly predicted mCR. Only ferritin correlated with diagnostic modified Curie scores (P = 0.003) but had a low correlation coefficient of 0.353. On multivariable analysis, the only significant covariate for 2-year overall survival at diagnosis was LDH <750 U/l (P = 0.024). A post-induction chemotherapy modified Curie score ≤3.0 had a 2-year overall survival of 46.2% compared with 30.8% for a score >3.0 (P = 0.484).

CONCLUSION

LDH, ferritin and the diagnostic ¹²³I-mIBG scans significantly predicted mCR, but only LDH predicted 2-year overall survival. Ferritin and the modified Curie scores correlated with each other. MYCN amplification neither correlated with any aspect of the ¹²³I-mIBG scans nor significantly predicted mCR or 2-year overall survival. LDH and ferritin are therefore appropriate neuroblastoma tumour markers to be used in low- and middle-income countries with limited or no access to mIBG scans and/or MYCN amplification studies.

Impact of implementing an online interactive educational tool for future HIV "cure" research in an HIV clinic waiting room in Cape Town, South Africa

Access to antiretroviral treatment (ART) in South Africa is suboptimal and erratic. For those on treatment, compliance remains a significant challenge. Interruptions to ART have negative implications for the individual and the epidemic. ART is therefore not a sustainable solution and there is an urgent need for a cure. As HIV cure research expands globally, the need to engage community members about cure is becoming a priority. It is vital that potential trial participants understand basic HIV cure research concepts. An online interactive educational tool was co-created with HIV stakeholders to engage and inform HIV research trial participants. The study was conducted with patients at the FAMCRU HIV clinic at Tygerberg Hospital in Cape Town, South Africa. The educational tool comprises two modules that provide information on HIV prevention, treatment and cure research. Participants completed a questionnaire before and after interacting with the programme. There was a significant increase in knowledge scores of participants demonstrated after using the tool. The interactive tool was successful in increasing participants' knowledge of HIV prevention, treatment and cure research.

Charge breeding of radioactive isotopes at the CARIBU facility with an electron beam ion source

An Electron Beam Ion Source Charge Breeder (EBIS-CB) has been developed at Argonne National Laboratory as part of the californium rare ion breeder upgrade. For the past year, the EBIS-CB has been undergoing commissioning as part of the ATLAS accelerator complex. It has delivered both stable and radioactive beams with A/Q < 6, breeding times <30 ms, low background contamination, and charge breeding efficiencies >18% into a single charge state. The operation of this device, challenges during the commissioning phase, and future improvements will be discussed.

Weight Gain in Asian Patients on Second-generation Antipsychotics

Introduction: There is increasing evidence that second-generation antipsychotics are associated with weight gain. However almost all available literature has been for Caucasian populations. Materials and Methods: A health quality improvement project was undertaken at the Institute of Mental Health/Woodbridge Hospital to monitor patients who were started on second-generation antipsychotics. This 2-year survey of 266 patients on second-generation antipsychotics closely tracked weight gain and other physical and biochemical parameters. Results: Of the 222 patients regularly monitored, 78.4% had weight gain (mean weight gain 1.9 kg, maximum weight gain 20.1 kg). Weight gain group liability was highest for clozapine (72.4%), followed by olanzapine (66.7%) and risperidone (65%). Most of the weight gain occurred in the first 4 weeks of treatment and 95.9% of those who gained weight had done so in the first 6 months. The maximum weight gain was seen at 12 weeks for risperidone and 8 weeks for clozapine, quetiapine and olanzapine; the latter having another peak at 6 months. Conclusion: The survey confirms that weight gain is also a problem for Asian patients treated with second-generation antipsychotics. It reinforces the need for the regular monitoring of patients and the need for psychoeducation and advice on diet and a healthy lifestyle. Key words: Atypical antipsychotic medication, Physical monitoring

Weight gain in Asian patients on second-generation antipsychotics

INTRODUCTION

There is increasing evidence that second-generation antipsychotics are associated with weight gain. However almost all available literature has been for Caucasian populations.

MATERIALS AND METHODS

A health quality improvement project was undertaken at the Institute of Mental Health/Woodbridge Hospital to monitor patients who were started on second-generation antipsychotics. This 2-year survey of 266 patients on second-generation antipsychotics closely tracked weight gain and other physical and biochemical parameters.

RESULTS

Of the 222 patients regularly monitored, 78.4% had weight gain (mean weight gain 1.9 kg, maximum weight gain 20.1 kg). Weight gain group liability was highest for clozapine (72.4%), followed by olanzapine (66.7%) and risperidone (65%). Most of the weight gain occurred in the fi rst 4 weeks of treatment and 95.9% of those who gained weight had done so in the fi rst 6 months. The maximum weight gain was seen at 12 weeks for risperidone and 8 weeks for clozapine, quetiapine and olanzapine; the latter having another peak at 6 months.

CONCLUSION

The survey confirms that weight gain is also a problem for Asian patients treated with second-generation antipsychotics. It reinforces the need for the regular monitoring of patients and the need for psychoeducation and advice on diet and a healthy lifestyle.

Are opportunities for vitamin A supplementation being utilised at primary health-care clinics in the Western Cape Province of South Africa?

OBJECTIVES

To determine missed opportunities and problems relating to implementation of the Vitamin A Supplementation Programme in urban and rural regions of the Western Cape Province of South Africa.MethodA cross-sectional survey was conducted at primary health-care (PHC) clinics in Cape Metropole, an urban region, and West Coast Winelands, a rural region, of the Western Cape. A purposive sample of clinics where more than 30 children were seen per day was drawn from 10 of the 11 districts in the Cape Metropole region and the two districts of the West Coast Winelands region. The number of children selected from each district was weighted in terms of population size for the two regions. At each clinic visited, the first five to 10 children seen on a day, and meeting the inclusion criteria for vitamin A supplementation (VAS) based on the vitamin A provincial policy guidelines, were selected. These included children with low birth weight (LBW), growth faltering, underweight and severe undernutrition, recurrent diarrhoea and lower respiratory tract infection (LRTI), tuberculosis, measles, HIV/AIDS and eye signs of vitamin A deficiency. Clinic records were reviewed following consultation with the PHC nurse to identify if the child required vitamin A, exit interviews were conducted with mothers/caregivers, and Road to Health Charts (RTHCs) were reviewed. At the end of the study, PHC managers were interviewed to determine if problems could be identified with the Programme.

RESULTS

Forty-three of 123 (35%) and 13 of 40 (33%) of the fixed PHC clinics in the Cape Metropole and West Coast Winelands regions were visited, and a total of 300 children (234 from Cape Metropole, 66 from West Coast Winelands) with a mean (standard deviation) age of 24.3 (16.3) months and who met the inclusion criteria for VAS were selected. Of the total sample of children, 198 (66%) had multiple (i.e. more than one) indication and 102 (34%) had a single indication for VAS. There were a total of 617 indications for VAS in the two regions; 238 (39%) for growth faltering, 119 (19%) for underweight, 98 (16%) for LBW, 70 (11%) for LRTI, 51 (8%) for diarrhoea, 21 (3%) for HIV/AIDS and 20 (3%) for tuberculosis. A total of 102 (34%) of the children in the two regions received vitamin A supplements (Cape Metropole 29%; West Coast Winelands 52%). A record was made on the RTHC of 79 (77%) of the children who received VAS (Cape Metropole 76%; West Coast Winelands 79%). Twenty-four per cent of the mothers knew why their child had been given vitamin A (Cape Metropole 29%; West Coast Winelands 12%). Eleven per cent of the mothers had previously heard about the Vitamin A Supplementation Programme (Cape Metropole 12%; West Coast Winelands 6%). More than 81% of PHC managers indicated that health staff had been trained to implement the Vitamin A Supplementation Programme. The main problems identified by health staff in the two regions were lack of vitamin A capsules, inadequate training and difficulties in implementing the Programme.

CONCLUSIONS

Opportunities to administer vitamin A were underutilised in both regions. Recommendations such as improving mothers' awareness of the benefits of vitamin A and training of PHC nurses were made to the provincial Department of Health and are being implemented to improve the effectiveness of the Programme.

Iron and the folate-vitamin B12-methylation pathway in multiple sclerosis

Some subjects with multiple sclerosis (MS) present with low blood iron parameters. Anecdotal reports and a single patient study suggest that iron supplementation may be beneficial in these subjects. Myelin is regenerated continually, but prerequisites for this process are iron and a functional folate-vitamin B12-methylation pathway. The aim of this study was to determine iron status, folate and homocysteine in MS subjects, and to evaluate the effect on MS symptoms if deficiencies were addressed.

RESULTS

In relapsing-remitting MS subjects, serum iron concentration correlated significantly with age at diagnosis (r=0.49; p=0.008). In Caucasian female MS subjects, serum iron and ferritin concentrations were significantly lower than in matched controls. In a 6-month pilot study, 12 subjects taking a regimen of nutritional supplements designed to promote myelin regeneration, improved significantly neurologically as measured by the Kurzke EDSS (Total Score means 3.50 to 2.45, 29.9%; p=0.021). These were significantly improved (p=0.002) compared to 6 control group patients taking multivitamins (Kurzke Score increased by 13.9% from 4.83 to 5.50). Both groups had significantly reduced homocysteine concentrations at 6 months, suggesting that methylation is necessary but not sufficient for myelin regeneration.

The role of nutrition and micronutrients in paediatric HIV infection

It has been postulated that micronutrients play a role in the pathogenesis of HIV disease. Though data are sparse, there is evidence that HIV-infected adults and children have a range of micronutrient deficiencies with increasing severity in advanced disease and in the presence of malnutrition. It appears that micronutrient deficiencies contribute to immune dysfunction, infectious morbidity and disease progression. Limited interventive studies suggest that vitamin and mineral supplementation is beneficial to HIV-infected adults and children; however, current, regimens are not evidence-based and there are no randomised controlled trials in children. There are a number of African studies under way addressing these issues.

A proposed vitamin A supplementation programme for South Africa--design, coverage and cost

BACKGROUND

A national survey of the micronutrient status of preschool children in South Africa established that vitamin A deficiency is a significant public health problem, requiring urgent attention. A number of immediate and long-term interventions were recommended, including the introduction of a vitamin A supplementation programme and a food fortification programme.

OBJECTIVES

The aim of the study was to assist in the development and implementation of a national vitamin A supplementation programme at primary health care facilities for mothers and children. This was achieved by determining the design, coverage and cost of a national primary health care facility vitamin A supplementation programme.

METHODS

Based on an extensive review of the literature, the main components of a primary health care facility vitamin A supplementation programme were identified. The annual, recurrent costs of each of the programme components were estimated for the nine provinces in South Africa. Immunisation coverage rates were used as a proxy for estimating the coverage of the programme.

RESULTS

The main components of the programme were identified as: promotion, training, purchase of vitamin A capsules, distribution of vitamin A capsules to primary health care facilities, distribution of capsules to the programme beneficiaries, and monitoring and evaluation. The programme would operate from primary health care facilities and would target all children between 6 and 24 months of age and newly delivered mothers. It was estimated that the programme would cover 74% of children and 95% of postpartum women nationally. The total annual, recurrent cost of the national programme was estimated at R16.4 million. The bulk of the costs would include personnel costs, comprising 68% of the total costs. Other costs included promotion (27%), vitamin A capsules (4%) and training (1%). The cost of the programme would vary significantly by province, but the provinces' average total cost per beneficiary would be similar.

CONCLUSION

A primary health care facility vitamin A supplementation programme has been designed and accompanied by an estimated overall cost and coverage for implementation. The findings of the study showed that the programme would be financially feasible and would reach the majority of children under 24 months of age. It is recommended that further research be undertaken to extend the programme to the more 'hard to reach' population using other strategies such as mass immunisation campaigns.

Motorized cart driver safety in assisted living

When a group of residents at a life care facility purchased motorized carts to move around the 350,000-square-foot facility, staff members were faced with the need to ensure the safety of both drivers and pedestrians. This article describes a safety assessment procedure developed for cart drivers who lived in the assisted living area of the community. Five performance criteria were selected for the safety assessment: the ability to safely moving into and out of the vehicle, demonstrate safe reaction times, take appropriate evasive action to sudden obstructions in the driver's path, turn the vehicle around safely, and park the vehicle without hitting walls or other objects.

Differences in disclosure of sexuality among African American and White gay/bisexual men: implications for HIV/AIDS prevention

Gay and bisexual men were asked if they had disclosed their sexuality to family members, heterosexual friends, gay friends, coworkers, health care workers, and members of their church; if they had been associated with groups made up of gays, bisexuals, and lesbians; and if they had gay/bisexual friends. White men were much more likely to disclose their sexuality, to have associated with groups and to have gay/bisexual friends. As education increased, white men were more likely, and African American men less likely, to disclose sexuality and associate with groups. Having gay/bisexual friends increased with education with both groups. The difference in disclosure can be traced to the higher social stigma apparently attached to being gay in the African American community, which may be exacerbated for more educated men. As a result, African American gay men may be less likely to participate in the fight against HIV/AIDS.

latheo encodes a subunit of the origin recognition complex and disrupts neuronal proliferation and adult olfactory memory when mutant

The Drosophila latheo (lat) gene was identified in a behavioral screen for olfactory memory mutants. The original hypomorphic latP1 mutant (Boynton and Tully, 1992) shows a structural defect in adult brain. Homozygous lethal lat mutants lack imaginal discs, show little cell proliferation in the CNS of third instar larvae, and die as early pupae. latP1 was cloned, and all of the above mentioned defects of hypomorphic or homozygous lethal lat mutants were rescued with a lat+ transgene. lat encodes a novel protein with homology to a subunit of the origin recognition complex (ORC). Human and Drosophila LAT both associate with ORC2 and are related to yeast ORC3, suggesting that LAT functions in DNA replication during cell proliferation.

Human CDC6/Cdc18 associates with Orc1 and cyclin-cdk and is selectively eliminated from the nucleus at the onset of S phase

In a two-hybrid screen for proteins that interact with human PCNA, we identified and cloned a human protein (hCdc18) homologous to yeast CDC6/Cdc18 and human Orc1. Unlike yeast, in which the rapid and total destruction of CDC6/Cdc18 protein in S phase is a central feature of DNA replication, the total level of the human protein is unchanged throughout the cell cycle. Epitope-tagged protein is nuclear in G1 and cytoplasmic in S-phase cells, suggesting that DNA replication may be regulated by either the translocation of this protein between the nucleus and the cytoplasm or the selective degradation of the protein in the nucleus. Mutation of the only nuclear localization signal of this protein does not alter its nuclear localization, implying that the protein is translocated to the nucleus through its association with other nuclear proteins. Rapid elimination of the nuclear pool of this protein after the onset of DNA replication and its association with human Orc1 protein and cyclin-cdks supports its identification as human CDC6/Cdc18 protein.

Identification of HsORC4, a member of the human origin of replication recognition complex

A new member of human origin recognition complex (ORC) has been cloned and identified as the human homologue of Saccharomyces cerevisiae ORC4. HsORC4 is a 45-kDa protein encoded by a 2.2-kilobase mRNA whose amino acid sequence is 29% identical to ScORC4. HsORC4 has a putative nucleotide triphosphate binding motif that is not seen in ScORC4. HsORC4P also reveals an unsuspected homology to the ORC1-Cdc18 family of proteins. HsORC4 mRNA expression and protein levels remain constant through the cell cycle. HsORC4P is coimmunoprecipitated from cell extracts with another subunit of human ORC, HsORC2P, consistent with it being a part of the putative human origin recognition complex.

Effect of combination therapy with zidovudine and didanosine on neuropsychological functioning in patients with symptomatic HIV disease: a comparison of simultaneous and alternating regimens

OBJECTIVE

To evaluate the effects of treatment with alternating and simultaneous regimens of zidovudine and didanosine on neuropsychological function in patients with symptomatic HIV-1 disease, focusing on patients with possible HIV-1-associated central nervous system (CNS) compromise at entry.

DESIGN

Randomized non-blinded clinical trial.

SETTING

Government medical research center.

PATIENTS

Thirty-eight patients with symptomatic HIV-1 disease, of whom 21 had evidence of CNS compromise at entry.

RESULTS

After 12 weeks of therapy, overall significant improvements in memory (P < 0.01) and focused attention (P < 0.001) were seen on both regimens. These gains, however, were largely limited to those patients with HIV-1-associated CNS compromise at entry (P < 0.05). Improvements were also noted in receptive vocabulary, reading, perceptual discrimination and reasoning, divided attention, motor strength, and in mood and affect. Improvements in those latter functions were generally of limited magnitude and were of comparable size for both compromised and non-compromised patients. There was no overall difference between the two drug regimens in the effects on CNS parameters.

CONCLUSIONS

Therapy-related improvements were noted particularly for patients with HIV-1-associated CNS compromise. Neuropsychological functions that have been implicated in AIDS dementia--memory and attention--showed the greatest gains. In contrast to the previously described superiority of the simultaneous regimen with regard to immunologic and virologic parameters, there was no difference between the regimens with regard to CNS measures. This supports the contention that the CNS constitutes a relative independent compartment in terms of HIV disease and treatment.

Inducible expression of a heterologous protein in Hansenula polymorpha using the alcohol oxidase 1 promoter of Pichia pastoris

Pichia pastoris (Pp) and Hansenula polymorpha (Hp) are methylotrophic yeasts commonly used for industrial purposes. Growth of either of these yeasts in the presence of methanol as the carbon source results in high-level induction of alcohol oxidase expression. The respective alcohol oxidase genes, AOX1 in Pp and MOX in Hp, have similar regulatory characteristics. Our studies show that the Pp AOX1 promoter (AOX1p) can be used for methanol-induced expression of a heterologous gene in Hp. Furthermore, the size of an AOX1p-heterologous gene-AOX1 terminator cassette transcript synthesized in Hp is indistinguishable from that synthesized in Pp suggesting that transcription both initiates and terminates at the same sites in both yeast species. Induction of AOX1p in Hp demonstrates that the methanol-inducible regulatory mechanism in Hp is able to recognize and activate the Pp promoter in spite of extensive sequence variations between AOX1p and MOXp.

A novel approach to the determination and characterization of HIV dementia

BACKGROUND

Neuropsychological studies of the pattern and extent of cognitive impairment in HIV-infected patients have mostly used deviations from control values and/or cut-off scores as criteria for classification of dementia. There is, however, no agreement as to how to define impairment, and classification is imprecise.

METHOD

The current study used a dementia classification matrix, developed with a step-wise linear discriminant analysis of neuropsychological data from patients with primary neurodegenerative dementias, to classify symptomatic HIV patients as demented or non-demented, and further to differentiate cortical and subcortical dementia patterns. Thirty-two male and 2 female patients (mean age 39 +/- 2) with symptomatic HIV disease (mean absolute CD4 count 195 +/- 41) participated in the study.

RESULTS

Thirty-five per cent of patients were classified as demented. Of these, 83% showed a subcortical pattern and 17% a cortical profile of deficits. Significant differences between patients classified as subcortically demented and those categorized as normal on neuropsychological measures associated with subcortical integrity further validated the classification. Measures of psychiatric status between subgroups were similar.

CONCLUSION

Since certain treatments may delay or reverse cognitive deficits, the use of an objective classification method based on discriminant analysis may help to identify patients who may benefit from therapy.

Assessment of the Abbott IMx assay system for the measurement of human chorionic gonadotropin levels in the treatment of ectopic pregnancy

The rapid, accurate determination of serum human chorionic gonadotropin (beta-hCG) levels in the 900- to 2000-IU/L range is a critical element in the treatment of patients with suspected ectopic pregnancy. Using the Abbott IMx system (Abbott Laboratories, North Chicago, Ill), beta-hCG levels can be determined on an undiluted sample up to 1000 IU/L. A sample with beta-hCG level greater than 1000 IU/L is automatically diluted and the diluted sample redetermined. Unfortunately, employing a 1:200 fixed dilution can produce a working sample that contains an beta-hCG concentration that does not fall on a linear portion of the standard curve (<7.5 IU/L). This results in a calculated beta-hCG concentration (200 x observed value) that has high error (coefficient of variation up to 21.8%). Additionally, interfering substances in the reagents, which vary in quantity from lot to lot of reagents, further confound accurate beta-hCG determination by the system. Consequently, the Abbott IMx assay system cannot be used as recommended by the manufacturer for routine measurement of serum beta-hCG in the 900- to 2000-IU range. An alternate protocol employing at 1:10 dilution would allow a more accurate beta-hCG determination.

Glial growth factors are alternatively spliced erbB2 ligands expressed in the nervous system

Glial growth factors, proteins that are mitogenic for Schwann cells, and several ligands for the p185erbB2 receptor, are products of the same gene. Alternative splicing of the messenger RNA generates an array of putative membrane-attached, intracellular and secreted signalling proteins, at least some of which are expressed in the developing spinal cord and brain. These factors are probably important in the development and regeneration of the nervous system.

Sequence and structural analysis of surface protein antigen I/II (SpaA) of Streptococcus sobrinus

Streptococcal antigen I/II or the surface protein antigen A (SpaA) of Streptococcus sobrinus is an adhesin which mediates binding of the organism to tooth surfaces. The complete sequence of the gene which encodes SpaA has been determined. The gene consists of 4,584 bp and encodes a protein of 1,528 amino acid residues. The deduced amino acid sequence shows extensive homology with those of the cell surface adhesins from Streptococcus mutans serotypes c and f and from Streptococcus sanguis. Structural analysis of the N-terminal region (residues 50 to 550), which is rich in alanine and includes four tandem repeats of an 82-residue sequence, suggests that it adopts an alpha-helical coiled-coil conformation. Cell surface hydrophobicity may be associated with this region. The C-terminal region is more conserved and includes two tandem repeats of a 39-residue proline-rich sequence. A further proline-rich sequence in this region is predicted to span the cell wall. Although a hydrophobic sequence is present in the C-terminal region, it appears to be too short to span the cell membrane. Anchoring of SpaA in the cell membrane may therefore require some form of posttranslational modification or association with another membrane protein.

Cloning of the amino terminal nucleotides of the antigen I/II of Streptococcus sobrinus and the immune responses to the corresponding synthetic peptides

A portion of the antigen I/II (spaA, B, P1) gene of Streptococcus sobrinus 6715, containing the coding sequence for the amino terminal 684 amino acids of the protein, was cloned in bacteriophage lambda GT10. Selection was by immunological detection using a polyclonal antiserum to the antigen I/II from Strep. mutans. From the amino acid sequence, peptides were synthesized, 15 amino acids in length, that covered the entire sequence. In total, 260 synthetic peptides were synthesized and evaluated for their immunogenicity in Balb/C mice. Thirty-nine peptides were immunogenic, without carrier, and the antisera generated were tested for their ability to bind cells of Strep. mutans and Strep. sobrinus in a solid-phase assay. Antisera corresponding to peptides from five regions on the I/II molecule bound cells of both bacterial species. These peptides were then evaluated for their ability to stimulate in vitro murine lymphocyte proliferation, after in vivo immunization with Strep. sobrinus cells. Two of the peptides were capable of stimulating proliferation, as determined by incorporation of [3H]-thymidine into murine lymph node cells. The sequences of these 5 peptides were then compared to sequences found in the antigen I/II from Strep. mutans (Kelly et al., 1989). As expected, there was considerable homology between the cross-reactive peptides synthesized and the analogous region from Strep. mutans. This homology was not usually contiguous and suggests that the antibodies bind a face of antigen I/II that is in an alpha-helical conformation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Early pressure on the gluteus maximus rotation flap in sacral decubitus ulcer]

The myocutaneous gluteus maximus flap in V-Y technique has become the workhorse for covering extensive sacral pressure sores. clinical experience indicates that this flap can sustain pressure prior to the usual three week period. Transcutaneous pO2 measurements permitted us to follow the flaps perfusion and to develop a new mobilization regimen. Patients can lie in the supine position for 30 minutes immediately after surgery for two hourly intervals. Three days postoperatively the usual two-hour repositioning can be resumed. This regimen represents a considerable improvement for paraplegics and has shown a comparable complication rate in 18 cases.

Cryptic tetracycline resistance determinant (class F) from Bacteroides fragilis mediates resistance in Escherichia coli by actively reducing tetracycline accumulation

Escherichia coli bearing a cryptic tetracycline resistance determinant from Bacteroides fragilis expressed low-level constitutive resistance to tetracycline under aerobic, but not anaerobic, growth conditions and accumulated less tetracycline aerobically than did isogenic susceptible cells. This decreased uptake was energy dependent and reversible by increased concentrations of tetracycline, suggesting a saturable carrier-mediated active efflux mechanism. Decreased uptake was not seen when the cells were grown and assayed anaerobically. Other tetracycline resistance determinants (classes A to E) isolated from gram-negative enteric bacteria expressed resistance and generated active efflux of tetracycline under anaerobic as well as aerobic conditions. When the Bacteroides determinant was placed in the same cell with any of the class A to E tetracycline resistance determinants, there was an increase in resistance under aerobic conditions of as much as 48% more than was projected by adding the resistances expressed by the determinants individually. In cells bearing the class A determinant together with the Bacteroides determinant, saturation of the active efflux system required over twofold more exogenous tetracycline than did cells bearing the class A determinant alone. We have designated this new tetracycline resistance determinant class F.

Effects of toluene permeabilization and cell deenergization on tetracycline resistance in Escherichia coli

Resistance to tetracycline (Tcr) mediated by Tn10 and related Tcr determinants involves an inner membrane protein, TET (similar but not identical for different determinants), and a proton motive force-dependent efflux of tetracycline which keeps the drug away from its intracellular target, the ribosome (L. M. McMurry, R. E. Petrucci, Jr., and S. B. Levy, Proc. Natl. Acad. Sci. USA 77:3974-3977, 1980). However, the amount of tetracycline accumulated by bacteria does not always correlate with their resistance levels, suggesting that an additional resistance mechanism may be present. When we permeabilized susceptible and resistant Tn10-bearing cells with toluene, we found that protein synthesis in the two strains became equally sensitive to tetracycline. Therefore, the protein synthesis machinery was not a source of resistance, and an intact membrane was required for resistance. To determine whether resistance was entirely dependent on energy, we measured susceptibility to tetracycline after inhibition of proton motive force by starvation and specific inhibitors. An 80 to 90% loss of Tcr (measured by protein synthesis) resulted from partial deenergization of resistant cells. A remaining resistance (10- to 20-fold greater than that of susceptible cells) could not be eliminated by further deenergization. These findings indicated that, to a major extent, expression of Tn10 resistance required energy, presumably for tetracycline efflux. They also suggested the existence of a small component of Tcr having little or no energy dependence. Whether this component depends on tetracycline efflux or some other mechanism is not known, but presumably both high- and low-energy components of resistance reflect activity of TET protein.

Multiple tropomyosin polypeptides in chicken embryo fibroblasts: differential repression of transcription by Rous sarcoma virus transformation

We have found that cytoskeletal extracts of cultured chicken embryo fibroblasts contain at least seven distinct polypeptides (two major and five minor) which cross-react with antiserum to chicken smooth muscle tropomyosin. These polypeptides range in apparent molecular weight from 31,000 to 47,000, and each is encoded by mRNAs which specifically hybridize to cloned muscle tropomyosin cDNAs. These nonmuscle tropomyosin species and their respective mRNAs are electrophoretically distinct from those of chicken skeletal muscle and appear by genomic DNA blotting to comprise a part of a multigene tropomyosin family. In Rous sarcoma virus-transformed chicken embryo fibroblasts, synthesis of the tropomyosins is differentially repressed such that the synthesis of the major species (cp35 and cp33, cytoskeletal proteins of molecular weight 35,000 and 33,000, respectively) and three minor species is drastically reduced, whereas the synthesis of two of the minor species (cp32 and cp31) remains essentially unchanged. Analysis of cellular mRNA and runoff nuclear transcription experiments indicate that the repression of tropomyosin synthesis by Rous sarcoma virus transformation occurs at the level of transcription. This repression of tropomyosin synthesis is partially mimicked in normal chicken embryo fibroblasts during incubation in high-NaCl medium, a condition in which chicken embryo fibroblasts acquire many characteristics of transformed cells.

Interaction of tight binding repressors with lac operators. An analysis by DNA-footprinting

To increase our understanding of protein-DNA interaction in general, and in particular that of lac repressor with lac operator, we have investigated the interaction of tight binding (Itb) repressors with wild type (WT) operator and Oc operators. Nine Oc and a WT operator were cloned and sequenced. Three different Oc and an O+ were then chosen for the footprint analysis of six Itb repressors and WT repressor. Distinct protection patterns for the various repressor-operator pairs were observed at low repressor concentrations whereas, at high repressor concentrations, a stretch of 24 bases of the lower strand of the four different operators was protected in most cases. This protection pattern at high repressor concentration was almost completely redundant for all repressor-operator pairs, in spite of the fact that the affinities of the various pairs differed by more than three orders of magnitude. Two exceptions to this general observation were the two tight binding repressors R67 and R78a. These had been mapped in a region that codes for amino acid residues involved in subunit interaction. The two repressors showed reduced protection of O+ and of some Oc operators at the 3' (right) end of the lower strand. Dimethylsulfoxide, which is known to increase the affinity of O+ for repressor, did not increase the number of bases protected by WT repressor on the lower strand of O+. The footprinting results presented here clearly demonstrate that lac repressor can maximally protect about 24 bases of the lower strand of the operator and that the number and kind of interactions occurring in this region determine the strength of the repressor-operator interaction.

Correlation of glucocorticoid receptor binding sites on MMTV proviral DNA with hormone inducible transcription

Steroid hormones, when complexed to their receptors, recognize and bind specific DNA sequences and subsequently induce increased levels of transcription. The mechanisms of steroid hormone action were analyzed by constructing chimeric DNA molecules from portions of mouse mammary tumor virus envelope and long terminal repeat (LTR) regions ligated to the thymidine kinase (tk) gene of herpes simplex virus. This construction allowed the tk gene to be expressed in a hormone-responsive fashion upon transfection into Ltk- cells. Comparison of transcription data with in vitro binding data showed that hormone-responsive transcription can be directly correlated to the presence of steroid hormone receptor binding sites on the DNA. There are at least two such receptor binding sites in the LTR region, one between -202 and -137 and another between -137 and -50 base pairs from the RNA cap site, as well as a site near the 5' end of the envelope region. These results strengthen the hypothesis that steroid-receptor complexes regulate genes primarily by binding to DNA sites near the promoter region and thereby modulate transcription.