Mixed-methods study to assess an intervention for healthier lifestyles in primary healthcare

Background

Smoking, physical inactivity, low fruit and vegetable consumption, and obesity are common in Kosovo. The Accessible Quality Healthcare project is implementing a primary healthcare intervention that entails nurse-guided motivational counselling to facilitate lifestyle behaviour change. This study assesses the uptake of counselling and the impact on health behaviours and participants’ stages of health behaviour change as well as describes experiences and perceived benefits of motivational counselling.

Methods

Study participants (n = 907) were recruited from 12 municipalities participating in the Kosovo Non-Communicable Disease Cohort study. For the quantitative study, data on lifestyle behaviours, use of counselling, and stages for behavioural change were used. For the qualitative study, in-depth interviews were conducted with 26 cohort participants who had undergone motivational counselling.

Results

Motivational counselling was received by only 22% of the eligible participants in the intervention municipalities. Unhealthy behaviours remain high even in persons who underwent counselling (of whom 13% are smokers; 86% are physically inactive; 93% with inadequate fruit and vegetable consumption; 61% are obese). According to the qualitative study results, the participants that received counselling were very satisfied with the services but requested additional services such as group physical activity sessions and specialized services for smoking cessation.

Conclusions

More tailored and additional primary healthcare approaches in accordance with patients’ views need to be considered for the motivational counselling intervention to reach patients and efficiently facilitate lifestyle behaviour change.

Key messages

• The following tailored approaches are suggested: a) strengthened referral mechanism b) specialized services for smoking cessation; c) delivery of group physical activity sessions.

• More tailored and additional primary health care approaches in accordance with patients’ views need to be considered for the motivational counselling intervention.

Removing barriers to utilisation of support services for abused female adolescents in Nigeria slums

Background

Female adolescents in urban slums experience a plethora of violence. The inherent health inequalities in the urban slums also present barriers to adolescents’ access to support services that can alleviate the impact of violence and bring perpetrators to justice. Health facilities can play key proactive roles in facilitating effective responses to address the problems of violence. This research sought to answer the questions: what support services are available to female adolescents in the event of violence; what are the barriers to accessing these services; and what roles can health workers play in removing these barriers?

Methods

The study used an ethnographic approach involving 40 in-depth interviews and 9 focus group discussions with female adolescents, 17 in-depth interviews were conducted with health providers and community leaders. The study setting comprised intentionally sampled slum communities in Lagos and Oyo states, southwest Nigeria. Thematic data analysis was conducted to address the study questions.

Results

Potential support services available to female adolescents in the study setting included the Community Development Association, police, family members, and health facilities. Identified barriers to utilizing available support services included stigmatization, non-formalization of police reports of violence, ambiguous attitudes of health workers to abused adolescents, and unfamiliarity on the part of adolescents. Although resources are available to adolescents in the event of violence, the lack of coordination of services has led to gross inefficiency for intervening.

Conclusions

To address the inefficiency of services, the health sector is best positioned to ensure synergy among the key stakeholders to reduce stigma and stop abuse experience among adolescent girls. Beyond a reactionary, curative approach, health providers need to play a preventive role through education, advocacy, and coordination of interventions at the community level.

Key messages

• Health workers at primary health facilities need to support adolescents who experience violence, especially those who using their services.

• In addition, health workers are best positioned to create synergy among available support services to alleviate and mitigate the impact of violence on female adolescents in the community.

Antenatal care service delivery and factors affecting effective tetanus vaccine coverage in low- and middle-income countries: Results of the Maternal Immunisation and Antenatal Care Situational analysis (MIACSA) project

Objectives

To map the integration of existing maternal tetanus immunization programmes within antenatal care (ANC) services for pregnant women in low- and middle-income countries (LMICs) and to identify and understand the challenges, barriers and facilitators associated with high performance maternal vaccine service delivery.

Design

A mixed methods, cross sectional study with four data collection phases including a desk review, online survey, telephone and face-to-face interviews and in country visits was undertaken between 2016 and 2018. Associations of different service delivery process components with protection at birth (PAB) and with country groups were established. PAB was defined as the proportion of neonates protected at birth against neonatal tetanus. Regression analysis and structural equation modelling was used to assess associations of different variables with maternal tetanus immunization coverage. Latent class analysis (LCA), was used to group country performance for maternal immunization, and to address the problem of multicollinearity.

Setting

LMICs.

Results

The majority of LMICs had a policy on recommended number of ANC visits, however most were yet to implement the WHO guidelines recommending eight ANC contacts. Countries that recommended > 4 ANC contacts were more likely to have high PAB > 90%. Passive disease surveillance was the most common form of disease surveillance performed but the maternal and neonatal morbidity and mortality indicators recorded differed between countries. The presence of user fees for antenatal care and maternal immunization was significantly associated with lower PAB (<90%).

Conclusions

Recommendations include implementing the current WHO ANC guideline to facilitate increased opportunities for vaccination during each pregnancy. Improved utilisation of ANC services by increasing the demand side by increasing the quality of services, reducing any associated costs and supporting user fee exemptions, or the supply side can also enhance utilisation of ANC services which are positioned as an ideal platform for delivery of maternal vaccines.

The Effectiveness of a Family-Centered Childhood Obesity Intervention at the YMCA: A Pilot Study

Objective

Community-based, family-centered obesity prevention/treatment initiatives have been shown to be effective in reducing body mass index (BMI) and improving healthy habits in children if implemented with high intensity and sufficient duration. Let's Go! 5-2-1-0 Program (5-2-1-0) was incorporated into family-centered, monthly physical activity classes and cooking classes over six months delivered by Young Men's Christian Association (YMCA) staff. We hypothesized that implementation of this intervention would improve 5-2-1-0 knowledge attainment, increase healthy behavior (based on 5- 2-1-0 curriculum), and improve BMI and waist circumference measurements in children.

Methods

Children attending YMCA summer camps in Rochester, MN, during 2016 were recruited via study packets mailed to their families. Height, weight, and waist circumference measurements as well as the results of the Modified Healthy Habits Survey and the 5-2-1-0 Knowledge Acquisition Survey were recorded for each participating child at baseline and 6-month follow-up. The intervention group received monthly healthy habit reminder emails, and was invited to monthly evening cooking and physical activity classes for 7 sessions over a 6-month period.

Results

Fifteen families in the intervention group attended classes. Of those, 13 families regularly participated in (attended at least 5 out of 7) both the monthly physical activity and cooking classes. The children in the intervention group had a significant improvement in the number of Knowledge Acquisition Survey questions answered correctly (p<0.001), while there was no improvement in the control group. As compared to children in the control group, there was no significant change in BMI or waist circumference or healthy habits in the intervention group.

Conclusion

Our study findings indicate that our intervention resulted in improved knowledge about healthy habits, but did not significantly impact healthy habits or BMI. Potential reasons for this were the small sample size and the attenuated length and/or intensity of the intervention.

Herpes simplex virus type 2-infected dendritic cells produce TNF-α, which enhances CCR5 expression and stimulates HIV production from adjacent infected cells

Prior HSV-2 infection enhances the acquisition of HIV-1 >3-fold. In genital herpes lesions, the superficial layers of stratified squamous epithelium are disrupted, allowing easier access of HIV-1 to Langerhans cells (LC) in the epidermis and perhaps even dendritic cells (DCs) in the outer dermis, as well as to lesion infiltrating activated T lymphocytes and macrophages. Therefore, we examined the effects of coinfection with HIV-1 and HSV-2 on monocyte-derived DCs (MDDC). With simultaneous coinfection, HSV-2 significantly stimulated HIV-1 DNA production 5-fold compared with HIV-1 infection alone. Because <1% of cells were dually infected, this was a field effect. Virus-stripped supernatants from HSV-2-infected MDDCs were shown to enhance HIV-1 infection, as measured by HIV-1-DNA and p24 Ag in MDDCs. Furthermore these supernatants markedly stimulated CCR5 expression on both MDDCs and LCs. TNF-α was by far the most prominent cytokine in the supernatant and also within HSV-2-infected MDDCs. HSV-2 infection of isolated immature epidermal LCs, but not keratinocytes, also produced TNF-α (and low levels of IFN-β). Neutralizing Ab to TNF-α and its receptor, TNF-R1, on MDDCs markedly inhibited the CCR5-stimulating effect of the supernatant. Therefore, these results suggest that HSV-2 infection of DCs in the skin during primary or recurrent genital herpes may enhance HIV-1 infection of adjacent DCs, thus contributing to acquisition of HIV-1 through herpetic lesions.

Sex differentials in the uptake of antiretroviral treatment in Zambia

This study explores socio-structural factors that influence uptake of antiretroviral treatment (ART) in Zambia and assess differences between men and women. We conducted a case-control study nested in a community- and health facility-based survey, between September 2010 and February 2011. Cases were defined as HIV-positive individuals who, while eligible, never started ART and controls were HIV-positive individuals who were on ART. Cases and controls were matched by place of residence. We performed a conditional logistic regression analysis using a discrete logistic model stratified by sex. Overall, a significantly larger proportion of men (32.7%) than women (25.6%) did not uptake ART (Pearson χ(2) = 5.9135; p = 0.015). In the crude analysis, poor health status and low self-efficacy were common factors associated with non-uptake in both sexes. After adjusting for covariates, men were more likely than women to refuse ART even though men's self-rated health was lower than women's. In general, the adjusted analysis suggests that HIV status disclosure affects uptake in both sexes but women's uptake of ART is largely hampered by poverty-related factors while for men, side effects and social pressure, probably associated with masculinity, are more important barriers. Alarmingly men's health seems to deteriorate until they start treatment, in contrast to women. Understanding gender differences in uptake and attitudes to ART is a crucial component to providing effective and appropriate health care to both men and women living with HIV/AIDS in Zambia.

Vitamin D supplementation in Swiss infants

BACKGROUND

Various recent publications reported clinical manifestations of vitamin D deficiency in infants. Furthermore new research revealed additional properties of vitamin D for bone health and in the prevention of chronic diseases. However, prevalence data on actual supplementation rates are scarce. This study reports the prevalence of vitamin D supplementation in infants in Switzerland and presents risk factors for non-supplementation.

METHODS

In 2003, mothers of 2861 randomly selected infants aged 0-9 months received a questionnaire on infant feeding, including a question on vitamin D supplementation. The prevalence of vitamin D supplementation was calculated and its dependency on various factors analysed by multiple logistic regression.

RESULTS

64% of the infants had received vitamin D. The regression analysis yielded various significant risk factors for non-supplementation: young maternal age, German language region, Swiss nationality, siblings and breastfeeding. Protective factors were intake of folic acid during pregnancy and professional information on infant feeding. The protective effect of professional information varied significantly by region.

CONCLUSIONS

Given that the supplementation of vitamin D is recommended for all infants, the supplementation prevalence in Swiss infants is unsatisfactorily low. Various risk factors were identified and a positive impact of professional counselling on the supplementation rate could be demonstrated. In view of the new evidence emerging on additional preventive properties of vitamin D and the resurgence of rickets, the importance of vitamin D for infant health and ways to improve its promotion must be discussed anew.

Vitamin D supplementation in Swiss infants

BACKGROUND

Various recent publications reported clinical manifestations of vitamin D deficiency in infants. Furthermore new research revealed additional properties of vitamin D for bone health and in the prevention of chronic diseases. However, prevalence data on actual supplementation rates are scarce. This study reports the prevalence of vitamin D supplementation in infants in Switzerland and presents risk factors for non-supplementation.

METHODS

In 2003, mothers of 2861 randomly selected infants aged 0-9 months received a questionnaire on infant feeding, including a question on vitamin D supplementation. The prevalence of vitamin D supplementation was calculated and its dependency on various factors analysed by multiple logistic regression.

RESULTS

64% of the infants had received vitamin D. The regression analysis yielded various significant risk factors for non-supplementation: young maternal age, German language region, Swiss nationality, siblings and breastfeeding. Protective factors were intake of folic acid during pregnancy and professional information on infant feeding. The protective effect of professional information varied significantly by region.

CONCLUSIONS

Given that the supplementation of vitamin D is recommended for all infants, the supplementation prevalence in Swiss infants is unsatisfactorily low. Various risk factors were identified and a positive impact of professional counselling on the supplementation rate could be demonstrated. In view of the new evidence emerging on additional preventive properties of vitamin D and the resurgence of rickets, the importance of vitamin D for infant health and ways to improve its promotion must be discussed anew.

Topical negative pressure in wound management

OBJECTIVE

To investigate the role of topical negative pressure (TNP) therapy in the management of difficult wounds.

DESIGN

Prospective consecutive patient series.

PATIENTS AND SETTING

30 patients referred to our tertiary plastic and reconstructive surgical service with wounds deemed unsuitable for reconstructive surgery were treated between November 1997 and the end of December 1998. The mean pretreatment duration of the wounds was 418 days (range, 8-1650 days). All wounds were at least Grade III pressure sores.

INTERVENTION

Topical negative pressure therapy (TNP) using the VAC device (KCI Medical, San Antonio, USA). Suction (75-125 mmHg) was continuous for the first 48 hours, then intermittent (2 min on, 5 min off).

MAIN OUTCOME MEASURES

Achievement of wound healing endpoints: (1) complete healing of the wound; (2) obliteration of the wound cavity to allow surface dressings; or (3) closure of the wound by suture or skin graft.

RESULTS

TNP was successful in 26 out of 30 patients with mean therapy time of 35 days (range, 3-124 days). Healing was more rapid in acute (less than six weeks old) wounds. A reduction in the number of bacterial species and colonies was also observed during therapy.

CONCLUSION

TNP can, in some circumstances, promote rapid secondary wound healing. A further randomised trial of TNP versus more traditional wound management modalities is justified.

Peritonectomy and intraperitoneal chemotherapy in appendiceal and colorectal cancer

BACKGROUND

Peritoneal spread of gastrointestinal malignancies has been regarded as an incurable disease, and treatment has been aimed at short-term palliation. The use of cytoreductive surgery, including peritonectomy procedures and intraperitoneal chemotherapy, has been proposed with the intention of prolonging survival, and perhaps curing patients with peritoneal carcinomatosis from appendiceal and possibly colon cancers. A series of eight patients who have undergone this procedure at St George Hospital is presented, and the results obtained by other groups are reviewed.

METHOD

Eight patients fitted the criteria for peritoneal carcinomatosis between January 1996 and November 1998. In seven patients this was secondary to appendiceal or colon cancer. and one patient had signet ring cancer of the uterus. The surgical treatment involved removing all macroscopic evidence of disease, and this was followed by early postoperative intraperitoneal chemotherapy.

RESULTS

The eight patients (seven female, one male) ranged in age from 25 to 67 years. There were seven complications, including two patients with pelvic abscesses, and one patient who developed Tenchkoff catheter occlusion. There were three deaths, one due to pelvic sepsis after 30 days, and the other two were due to metastatic disease. Of the remaining five patients, two have developed recurrence and three remain disease-free.

CONCLUSION

The results of peritonectomy and intraperitoneal chemotherapy for appendiceal tumours are encouraging. The role in colorectal cancer is less clear, although there are some reports that suggest a benefit.

Induction of specific tolerance to allografts in rats by therapy with non-mitogenic, non-depleting anti-CD3 monoclonal antibody: association with TH2 cytokines not anergy

BACKGROUND

Anti-CD3 monoclonal antibodies (mAb) are potent immunosuppressives in transplantation but most do not induce tolerance. They induce anergy in Th1 cells but, if they bind to Fc receptors on antigen presenting cells, they activate T cells to release cytokines.

METHODS

This study examined the mechanisms of transplant tolerance induction to PVG fully allogeneic grafts in dark agouti rats by G4.18, a mouse immunoglobulinG3 anti-rat CD3 mAb that does not bind rat Fc receptors. Evidence of T cell activation was assayed by flow cytometry, reverse transcription (RT)-polymerase chain reaction (PCR) for cytokine mRNA, and responsiveness in mixed lymphocyte culture.

RESULTS

G4.18 treatment modulated T cell receptor/CD3 and CD2 and depleted T cells by <20% but did not induce activation surface markers. mRNA for interleukin (IL)-2, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and IL-4 in the lymph node, spleen, and thymus was not increased, and IFN-gamma mRNA was reduced. G4.18-treated and naive rat cells had similar proliferation and expression of IL-2, IFN-gamma, and IL-4 in vitro. G4.18-treated allograft recipients had no induction of mRNA for IL-2, IFN-gamma, TNF-alpha, TNF-beta, IL-4, IL-5, IL-10, perforin, and granzyme A & B in the spleen or grafts, with levels similar to those in isografts. The IL-4 and IL-5 mRNA levels in the spleen but not the graft of G4.18-treated recipients were higher than in rejecting and naive animals. Cells from G4.18-treated graft recipients proliferated more rapidly to the donor than to the third party and had increased IL-4 expression.

CONCLUSIONS

G4.18 induced transplant tolerance by a combination of modulation and blocking of the TCR/CD3, associated with increased Th2 cytokines, without depletion, induction of anergy, or nonspecific activation of T cells.

Silicone in nasal augmentation rhinoplasty: a decade of clinical experience

A number of materials, both biologic and alloplastic, have been used for nasal augmentation. Although biologic bone and cartilage grafts are associated with lower infection rates, they are also associated with long-term resorption and donor-site morbidity. Alloplastic materials, in particular silicone, have been associated in the literature with extrusion and infection but have the advantages of being affordable and easy to reshape with no requirement for harvesting autografts. A 10-year experience with silicone nasal augmentation documenting clinical experience, acute and long-term complications, and patient satisfaction was reviewed. All patients undergoing silicone augmentation rhinoplasty between July of 1985 and December of 1995 were reviewed. Preoperative nasal phenotype, operative data, and postoperative outcome were recorded. Long-term follow-up was undertaken using a telephone survey. There were 422 patients who underwent silicone nasal augmentation from July of 1985 to December of 1995. Only nine were men. The indications were for aesthetic nasal augmentation in 98 percent, and the majority (98 percent) were of South East Asian origin. Mean age was 26 (range 17 to 36), and 41 of the 422 patients had had previous nasal augmentation performed before presentation. Twenty-three patients (5.5 percent) had complications requiring removal of the implant within 30 days of surgery. These included displacement, prominence, hemorrhage, and excessive pressure in addition to obvious supratip deformity. On late follow-up, a further 18 patients (4.3 percent) had subsequent removal of the prosthesis. The most common reason for this was either displacement or over-prominence, more often judged by the surgeon than the patient. There were only two patients (0.5 percent) who had extrusion of the prosthesis. A total of 266 patients (63 percent) were contacted for a telephone interview. The majority of patients (84.2 percent) were satisfied with their nasal shape. Of the 42 patients (15.8 percent) who were not satisfied, 21 patients still wanted further augmentation of their nose. Photographic analysis of 198 patients showed a mean augmentation of 16.5 percent (range 4.0 to 27.5). Amount of augmentation correlated with preoperative nasal phenotype. Silicone nasal augmentation is a safe and effective procedure when used for moderate increases in nasal height. Contrary to previous reports, this series showed no associated infection. If the implant is shaped appropriately to the patient's nasal phenotype, the risk of extrusion may be reduced.

The cellular basis of cardiac allograft rejection: VIII. Mechanisms underlying delayed allograft rejection in PVG C6-deficient rats

BACKGROUND

The delayed allograft rejection in C6-deficient PVG C6- rats compared with normal PVG rats has been attributed to the lack of alloantibody activation of the membrane attack complex of complement. As T cells alone have been shown to effect graft rejection, we examined T-cell responses in PVG C6- rats.

METHODS

The cellular infiltrate and its mRNA for cytokines and effector molecules in DA heart allografts to PVG and PVG C6- rats was compared by immunoperoxidase staining and semiquantitative reverse transcriptase polymerase chain reaction. The ability of pure populations of T cells or alloantibody to mediate DA heart graft rejection in irradiated (750 rads) PVG and PVG C6- rats was also compared.

RESULTS

The median rejection time of DA heart allografts was 8 days in PVG rats and 17.5 days in PVG C6-. PVG C6- rats sensitized to DA by two skin grafts rejected DA heart grafts in 5-6 days. CD3+, CD4+, CD8+, interleukin-2 receptor-positive T cell, macrophage, and natural killer cell infiltration, as well as class II major histocompatibility complex and intercellular adhesion molecule-1 up-regulation, in grafts was similar in naive PVG and PVG C6- rats. mRNA for T helper 1 cytokine interleukin-2, interferon-gamma, tumor necrosis factor-beta, macrophage molecules tumor necrosis factor-alpha, and inducible nitric oxide synthase, as well as cytotoxic T-cell effector molecules perforin and granzyme A and B, were found to be the same in the grafts from both naive PVG and naive PVG C6- rats. Thus, there appeared to be no difference in the T-cell effector response between the PVG and PVG C6- groups. There were higher alloantibody titers in PVG C6- rats than in PVG hosts. Irradiation ablated rejection and alloantibody responses and reconstitution with naive T cells alone restored rejection in both PVG and PVG C6- rats. Irradiated rats given serum from PVG rats that had rejected DA grafts did not effect rejection of DA grafts even if given naive T cells. Sensitized T cells restored second set.

CONCLUSIONS

PVG C6- rats have normal T-cell responses and can mediate allograft rejection in the absence of alloantibody. The failure of PVG C6- to reject allografts rapidly may be a result of the poor clearance of alloantisera leading to enhancement of graft survival rather than a critical role for complement and membrane attack complex in acute rejection.

Molecular cloning of two fast myosin heavy chain cDNAs from chicken embryo skeletal muscle

Recombinant DNA clones containing sequences for two different types of myosin heavy chain (HC) genes from chicken embryonic skeletal muscle were constructed and analyzed. Specificity of the clones for myosin HC was demonstrated by hybrid-arrested translation, by hybridization to a 7.0-kb mRNA, and by comparison of DNA sequences with known amino acid sequences of rabbit skeletal muscle myosin HC. Restriction enzyme and electron-microscopic heteroduplex analysis showed the presence of two distinct but homologous cDNA sequences. Hybrid melting curves indicated that both types of sequences represent fast myosin HC sequences.

Processing of precursors of 21S ribosomal RNA from yeast mitochondria

The transcription and processing of mitochondrial 21S rRNA in a petite strain of Saccharomyces cerevisiae has been examined by electron microscopic analysis of R-loop hybrids and by hybridization of labeled mitochondrial DNA probes to RNA transferred to diazobenzyloxymethyl paper. We have shown the presence of a large [5.1- to 5.4-kilobase (kb)] transcript that appears to be a precursor of mitochondrial 21S rRNA. This transcript contains sequences homologous to those of the mature 21S rRNA, to the intervening sequence present in the gene, and to additional sequences at the 3' end of the molecule. Our data suggest that this precursor of 21S rRNA is processed in two steps. The intron sequence is usually excised first, followed by removal of the extra 3' sequences. In some cases, however, the 3' extension is first removed and the intron sequence is then excised. Both pathways appear to lead to formation of the 3.1-kb mature 21S rRNA and a stable 1.2-kb intron transcript. Similar results were obtained with grande MH41-7B mitochondrial RNA by RNA transfer hybridization. We have also observed a number of additional transcripts that may be normal processing intermediates or may result from faulty cleavage-ligation during excision of the intervening sequence.

Mitochondrial proliferation in cardiac hypertrophy

Mitochondrial proliferation was studied in mature female rats following aortic constriction. Mitochondrial DNA (mtDNA) was assayed by a fluorometric method. The conditions for removal of nuclear DNA were developed and verified by assessment of molecular conformation of DNA. The mtDNA concentration in mitochondria increased 2,4, and 7 days post-operatively by 11, 72 and 117% respectively. Comparison with the rates of accumulation of cytochrome c, b, and aa3 indicates that during the first 24 hours of cardiac enlargement the inner mitochondrial components accumulate faster then mtDNA, but during the six subsequent days the rate of mtDNA increment far outstrips that of the cytochromes. These data indicate that the amount of available mtDNA templates is not the only factor regulating the transcriptional and translational processes in the enlarging myocardium. The analysis of population of replicative intermediates of mtDNA have shown dramatic decrease in the frequency of D-loops in preparations obtained from hypertrophied hearts. This observation indicates that the increase in replicative flux of mtDNA is associated with the removal of a block in the conversion of D-loops to other intermediates.

Changes in mitochondrial DNA in cardiac hypertrophy in the rat

We studied DNA (mtDNA) replication in adult female rat hearts undergoing hypertrophy secondary to constriction of the ascending aorta. MtDNA was measured in isolated mitochondria by a fluorometric method adapted for that purpose. The conditions for removal of contaminating nuclear DNA were developed, and the purity of the mtDNA was assessed from its molecular conformation (open and closed circles) and by renaturation-kinetic analysis. The mtDNA concentration in mitochondria, expressed as micrograms of DNA per milligram of mitochondrial protein, increased 2, 4, and 7 days postoperatively by 21, 73, and 98%, respectively. Similar results were obtained when mtDNA was expressed per nonomole of cytochrome a. The population of replicative intermediates of mtDNA was analyzed by electron microscopy. In normal hearts, we observed molecular forms characteristic of animal mtDNA, such as circular monomers and dimers, catenated molecules, D-loops, expanded D-loops, and gapped molecules. D-loop frequency, which was near 50% in the mtDNA of control hearts, was markedly reduced to 5-7% in hypertrophying hearts. This result indicates that the increase in replicative flux of mtDNA is associated with the removal of a block in the conversion of D-loops to other intermediates.

Physical mapping of genes on yeast mitochondrial DNA: localization of antibiotic resistance loci, and rRNA and tRNA genes

We have physically mapped the loci conferring resistance to antibiotics that inhibit mitochondrial protein synthesis (erythromycin, chloramphenicol and paromomycin) or respiration (oligomycin I and II), as well as the 21s and 14s rRNA and tRNA genes on the restriction map of the mitochondrial genome of the yeast Saccharomyces cerevisiae. The mitochondrial genes were localized by hybridization of labeled RNA probes to restriction fragments of grande (strain MH41-7B) mitochondrial DNA (mtDNA) generated by endonucleases EcoRI, HpaI, BamHI, HindIII, SalI, PstI and HhaI. We have derived the HhaI restriction fragment map of MH41-7B mit DNA, to be added to our previously reported maps for the six other endonucleases. The antibiotic resistance loci (antR) were mapped by hybridization of 3H-cRNA transcribed from single marker petite mtDNA's of low kinetic complexity to grande restriction fragments. We have chosen the single Sal I site as the origin of the circular physical map and have positioned the antibiotic loci as follows: C (99.5-1.Ou)--P (27-36.Ou)--OII (58.3-62u--OI (80-84u)--E (94.4-98.4u). The 21s rRNA is localized at 94.4-99.2u, and the 14s rRNA is positioned between 36.2-39.8u. The two rRNA species are separated by 36% of the genome. Total mitochondrial tRNA labeled with 125I hybridized primarily to two regions of the genome, at 99.5-11.5u and 34-44u. A third region of hybridization was occasionally detected at 70--76u, which probably corresponds to seryl and glutamyl tRNA genes, previously located to this region by petite deletion mapping.