Exploring new balance and gait factors that are associated with osteosarcopenia in patients with a previous fall and/or fracture history

Osteosarcopenic individuals have poor muscle function and increased bone fragility, which results in a severe detriment to health outcomes. Hence, there is a necessity to discover easily accessible factors associated with osteosarcopenia to develop timely interventions. This study aimed to determine new sensitive balance and/or gait variables that are associated with osteosarcopenia in a population of older people with a history of falls and/or fractures. In a cross-sectional cohort study, 306 men and women aged ≥65 years completed a series of questionnaires, clinical assessments and muscle strength and function tests. Subsequently, participants were separated into osteopenia, osteoporosis and osteosarcopenia, groups for comparison and further analysis. Osteosarcopenia performed worse than osteopenia and osteoporosis in grip strength, gait speed, physical function scores and in multiple gait and balance indices (p<0.001). During posturography testing, there were larger elliptical areas with eyes open (p = 0.003), and eyes closed (p = 0.043) and increased sway velocity on a firm platform (p = 0.007) in the osteosarcopenia group, compared to osteoporosis. Limits of stability and eyes open ellipse area significantly contributed to the multivariable model (p = 0.029 and p = 0.038, respectively), suggesting that these balance parameters, along with grip strength, may be useful in identifying older adults with osteosarcopenia from those with only osteopenia/osteoporosis. Older adults with osteosarcopenia and a history of falls and/or fractures demonstrated inferior strength, function, and gait characteristics. This study identified indices of balance that were sensitive discriminators for osteosarcopenia and could be easily implemented into routine assessment.

Classification of Fracture Risk in Fallers Using Dual-Energy X-Ray Absorptiometry (DXA) Images and Deep Learning-Based Feature Extraction

Dual-energy X-ray absorptiometry (DXA) scans are one of the most frequently used imaging techniques for calculating bone mineral density, yet calculating fracture risk using DXA image features is rarely performed. The objective of this study was to combine deep neural networks, together with DXA images and patient clinical information, to evaluate fracture risk in a cohort of adults with at least one known fall and age-matched healthy controls. DXA images of the entire body as, well as isolated images of the hip, forearm, and spine (1488 total), were obtained from 478 fallers and 48 non-faller controls. A modeling pipeline was developed for fracture risk prediction using the DXA images and clinical data. First, self-supervised pretraining of feature extractors was performed using a small vision transformer (ViT-S) and a convolutional neural network model (VGG-16 and Resnet-50). After pretraining, the feature extractors were then paired with a multilayer perceptron model, which was used for fracture risk classification. Classification was achieved with an average area under the receiver-operating characteristic curve (AUROC) score of 74.3%. This study demonstrates ViT-S as a promising neural network technique for fracture risk classification using DXA scans. The findings have future application as a fracture risk screening tool for older adults at risk of falls. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Diagnostic power of relative sit-to-stand muscle power, grip strength, and gait speed for identifying a history of recurrent falls and fractures in older adults

PURPOSE

To compare the diagnostic value of relative sit-to-stand muscle power with grip strength or gait speed for identifying a history of recurrent falls and fractures in older adults.

METHODS

Data from an outpatient clinic included anthropometry (height/weight), bone density, 5 times sit-to-stand time (stopwatch and standardized chair), grip strength (hydraulic dynamometer), and gait speed (4 m). Relative sit-to-stand muscle power (W.kg^-1, normalised to body mass) was calculated using a validated equation. Outcomes of falls (past 1 year) and fractures (past 5 years) were self-reported and verified by medical records wherever possible. Binary logistic regression considering for potential confounders (age, sex, BMI, Charlson comorbidity index, femoral neck bone density) and receiver operating characteristics (ROC) curves were used in statistical analysis.

RESULTS

508 community-dwelling older adults (median age: 78 years, interquartile range: 72, 83, 75.2% women) were included. Compared to greater relative sit-to-stand muscle power (1.62-3.78W.kg^-1 for women; 2.03-3.90W.kg^-1 for men), those with extremely low relative sit-to-stand muscle power were 2.35 (95% CI 1.54, 3.60, p < 0.001) and 2.41 (95% CI 1.25, 4.65, p = 0.009) times more likely to experience recurrent falls and fractures, respectively, in fully adjusted model. Compared to grip strength or gait speed, relative sit-to-stand muscle power showed the highest area under the ROC curve for identifying recurrent falls (AUC: 0.64) and fractures (AUC: 0.62). All tests showed low diagnostic power (AUC: < 0.7).

CONCLUSION

Relative sit-to-stand muscle power performed slightly (but not statistically) better than grip strength or gait speed for identifying a history of recurrent falls and fractures in older adults. However, all tests showed low diagnostic power.

Comparing the Fracture Profile of Osteosarcopenic Older Adults with Osteopenia/Osteoporosis Alone

PURPOSE

To determine whether osteosarcopenia is associated with a greater likelihood of recurrent fractures, as well as type of fracture, than osteopenia/osteoporosis or sarcopenia alone.

METHODS

Anthropometry (height/weight; scales and stadiometer), body composition (bone mineral density [BMD] and appendicular lean mass; dual-energy x-ray absorptiometry), grip strength (hydraulic dynamometer), and gait speed (4 m) were measured in an outpatient clinic. WHO definition for osteopenia/osteoporosis (BMD T-score below -1 SDs) while sarcopenia was defined by SDOC or EWGSOP2. Number and location of fractures within the past 5 years were self-reported and verified by medical records (unverified fractures excluded). Univariable and multivariable regressions were used to examine the association between the exposure and outcome while adjusting for confounders.

RESULTS

481 community-dwelling older adults (median age: 78, IQR: 72, 83; 75.9% women) were included. Prevalence of osteosarcopenia depended on the definition (SDOC: 179 (37.2%); EWGSOP2: 123 (25.6%)). In multivariable analysis adjusting for age, sex, alcohol, smoking, BMI, lowest BMD T-score, physical activity, and comorbidities, the likelihood of recurrent fractures (≥ 2 vs 0-1) was significantly higher in those with osteosarcopenia versus osteopenia/osteoporosis irrespective of the definition (SDOC: odds ratio [OR]: 1.63, 95% CI: 1.03, 2.59, p = 0.037; EWGSOP2: OR: 1.83, 95% CI: 1.12, 3.01, p = 0.016]. Associations with sarcopenia alone (SDOC: 10; EWGSOP2: 7) were not possible due to the extremely low prevalence of this condition in those with normal BMD.

CONCLUSION

Our data suggest osteosarcopenia is associated with a greater likelihood of recurrent fractures versus osteopenia/osteoporosis alone. Further studies are needed to evaluate the relationship with sarcopenia alone.

Serum levels of C-terminal telopeptide (CTX) are associated with muscle function in community-dwelling older adults

BACKGROUND

Markers of bone metabolism have been associated with muscle mass and function. Whether serum cross-linked C-terminal telopeptides of type I collagen (CTX) is also associated with these measures in older adults remains unknown.

METHODS

In community-dwelling older adults at high risk of falls and fractures, serum CTX (biochemical immunoassays) was used as the exposure, while appendicular lean mass (dual-energy x-ray absorptiometry) and muscle function (grip strength [hydraulic dynamometer], short physical performance battery [SPPB], gait speed, sit to stand, balance, Timed Up and Go [TUG]) were used as outcomes. Potential covariates including demographic, lifestyle and clinical factors were considered in statistical models. Areas under the ROC curves were calculated for significant outcomes.

RESULTS

299 older adults (median age: 79 years, IQR: 73, 84; 75.6% women) were included. In multivariable models, CTX was negatively associated with SPPB (β = 0.95, 95% CI: 0.92, 0.98) and balance (β = 0.92, 0.86, 0.99) scores, and positively associated with sit to stand (β = 1.02, 95% CI: 1.00, 1.05) and TUG (β = 1.03, 95% CI: 1.00, 1.05). Trend line for gait speed (β = 0.99, 95% CI: 0.98, 1.01) was in the hypothesized direction but did not reach significance. AUC curves showed low diagnostic power (<0.7) of CTX in identifying poor muscle function (SPPB: 0.63; sit to stand: 0.64; TUG: 0.61).

CONCLUSION

In older adults, higher CTX levels were associated with poorer lower-limb muscle function (but showed poor diagnostic power for these measures). These clinical data build on the biomedical link between bone and muscle.

COVID-19 conversations: A qualitative study of majority Hispanic/Latinx youth experiences during early stages of the pandemic

Background

Growing evidence informs about the detrimental impact that COVID-19 has had on youths' mental health and well-being. As of yet, no study has directly examined the experiences and perspectives of children and young adolescents from racial and ethnic minority groups in the U.S., despite being exposed to more adversity, which may affect coping with the many challenges posed by the pandemic.

Objective

This study aimed to give voice to a mostly Hispanic/Latinx group of youth regarding the impact of COVID-19 stay-at-home measures and to identify their emotional responses and coping strategies amid the pandemic in the U.S. when restrictions were at their hardest.

Method

A total of 17 youths (70.6 % Hispanic; age range = 10-14 years; 52.9 % female) participated in four virtual semi-structured focus groups for each grade level (grades 5-8). Data was transcribed and analyzed using a gold standard thematic analysis approach.

Results

Seven themes were identified concerning the impact of COVID-19, centering around the impact of racism, loss of income, the role of community and family in coping with stress, information overload, home-schooling, loneliness and boredom, and lack of structured routines.

Conclusions

Our findings suggest that cultural factors (e.g., collectivism and familism) in Hispanic communities may offer important buffering during COVID-19. Future research studies evaluating the implementation of structured programs that provide a space to talk about emotions and thoughts related to the impact of the pandemic and training in strategies to cope with distress during mandatory home-schooling are needed.

Outdoor physical activity for older people-the senior exercise park: Current research, challenges and future directions

ISSUE ADDRESSED

Exercising outdoors provide beneficial effect on mental and physical health for all ages. However, few older people exercise outdoors other than walking. While outdoor gyms have become increasingly common in Australia, limited outdoor exercise equipment specifically designed for older people is available in public spaces. We have set up and evaluated a unique purpose-built outdoor exercise park for older people in the community setting and demonstrated positive physical and wellbeing outcomes associated with the provision of this unique exercise mode and social program.

METHODS

This study is a reflective narrative describing this innovative exercise approach and reports challenges associated with establishment of the exercise park, conducting the randomised trial, strategies adopted to address these challenges and recommendations for future implementation of this approach in the community.

RESULTS

Many challenges were encountered, including securing appropriate land to locate the exercise park, control of environmental factors for safety (non-slippery ground and equipment) as well as logistics in running the exercise program itself. Several adjustments in the equipment were also required to ensure safe use by older people.

CONCLUSION

The inclusion of outdoor equipment for older people in public spaces or urban parks is important and careful consideration needs to be taken by local/public authorities to provide access, amenities and safety for all as well as activities to suit all ages. SO WHAT?: Seniors' exercise parks can be installed in public places and may provide an enjoyable and effective approach to engage older individuals in a more active and healthier lifestyle.

Relationships between self perceptions and physical activity behaviour, fear of falling, and physical function among older adults

Background

There has been a lack of research examining the relationship among self-perceptions, behaviour, cognitions and functioning in older adults. This study, therefore, examined the relationship between global and physical self-perceptions, physical activity behaviour, and fear of falling taking into considerations objective measures of physical functioning in community dwelling older adults.

Methods/design

Sixty-six participants between 60 and 90 years old (71.9 ± 6.6 years; 47 females; 19 males) completed questionnaires assessing physical and global self-description (PSDQ), planned and incidental physical activity behaviour (IPEQ), and falls efficacy (Short FES-I) as well as tests measuring physical functioning. Backwards multiple linear regression modelling was used to assess possible relationships among variables.

Results

Findings showed that physical self-perceptions (activity, coordination, endurance, flexibility) were associated with self-reported planned and incidental PA whereas sit-to-stand was the only objectively measured physical functioning variable associated with planned PA. Similarly, more falls, global self-esteem, general physical and domain specific physical self-perceptions (flexibility and strength) as well as knee strength were associated with fear of falling. There were also associations between some of the objectively measured physical functioning variables and self-perceptions of the physical self, providing some predictive validity for the PDSQ.

Conclusions

The findings of this study come to corroborate that the belief system of older adults ideally need to be taken into consideration when designing interventions that aim to enhance PA behaviour or reduce fear of falling. Coupling that with goal-setting, life coaching and behaviour change strategies would also be beneficial to address engagement and adherence to such interventions.

Trial registration

This trial was retrospectively registered with the Australian New Zealand Clinical Trials Registry - Registry No. ACTRN12614000700639 on the Jul 03rd 2014.

A Novel Exercise Initiative for Seniors to Improve Balance and Physical Function

OBJECTIVE

To investigate the feasibility, effectiveness, and short-term effects of an exercise intervention using a novel exercise park in improving seniors' balance, physical function, and quality of life.

METHOD

Randomized controlled trial with pre- and post-intervention design (baseline and 18-week intervention) was used. Outcome measures included measures of balance, strength, and function, as well as quality of life and fear of falling. MANCOVA was used to assess differences between groups (control and exercise intervention) over time.

RESULTS

Intervention group showed significant improvement on single leg stance ( p = .02, 95% confidence interval [CI] = [-8.35, -0.549]), knee strength ( p < .01, 95% CI = [-29.14, -5.86]), 2-min walk ( p = 0.02, 95% CI = [-19.13, -0.859]), and timed sit to stand ( p = .03, 95% CI = [-2.26, -0.143]) tests.

DISCUSSION

The exercise park program improved physical function and had high adherence and participation rate. Such intervention has been shown to be safe and therefore might enhance participation in exercise programs for older adults.

Autoimmune pancytopenia following combination chemotherapy for chronic lymphocytic leukaemia: Figure 1

Autoimmune haemolysis or thrombocytopenia can complicate purine nucleoside monotherapy for chronic lymphocytic leukaemia (CLL), but Evans syndrome is rare. This is a report of the occurrence of pancytopenia secondary to a unique combination of red cell aplasia with autoimmune thrombocytopenia and neutropenia in a patient with CLL following treatment with fludarabine and cyclophosphamide. This case is unusual for the simultaneous targeting of three haemopoietic lineages by immune dysfunction following fludarabine and cyclophosphamide, which is a treatment regimen believed to reduce autoimmune haematological toxicity in CLL.

Karyotypic aberrations of chromosomes 16 and 17 are related to survival in patients with breast cancer

BACKGROUND

Breast cancer has a high incidence and associated mortality rate, yet little is known of the sequence of genetic events that underlie the clinical course.

METHODS

The study was a comparative genomic hybridization analysis of 40 primary breast cancers with survival data at a mean of 8.4 years.

RESULTS

The mean number of aberrations was 9.0, with a mean of 5.5 gains and 3.5 deletions per tumour. The most common aberrations were: gain of 1q (27 of 40), 8q (19 of 40) and 17q (13 of 40), and deletion of 17p (12 of 40) and 8p (11 of 40). These results are consistent with a distinctive pattern of large-scale (karyotypic) genetic change in primary breast cancer.

CONCLUSION

The novel findings of this study were that only women who were disease-free had loss of 16q (E-cadherin) in association with a gain of 16p, and 17p13 (p53) loss combined with 17q12 (HER2) amplification was found only in the cancers of women who developed recurrent disease. The karyotypic changes seen in primary breast cancer seem to be associated with outcome and point to the underlying genetic events.

Syn-anti isomerization of aldols by enolization

[reaction--see text] A variety of aldol adducts (i.e., 3-hydroxy ketones) are shown to undergo syn-anti isomerization in the presence of imidazole by an enolization mechanism with negligible retroaldol or elimination products.

Chromosomal imbalances in gastric and esophageal adenocarcinoma: specific comparative genomic hybridization-detected abnormalities segregate with junctional adenocarcinomas

The incidence of adenocarcinoma arising at the esophagogastric junction (EGJ) is increasing at a rate greater than that for any other form of solid malignancy. Commensurate with this, the incidence of histologically similar tumors arising in the gastric body and antral mucosa is declining. The increased incidence of the proximal group of tumors may reflect, in part, the higher prevalence of Barrett esophagus. These epidemiological features suggest that histologically similar tumors arising at the EGJ and from the distal stomach are different, which may be reflected in the genetic abnormalities that characterize the two groups of tumors. The purpose of this study was to screen genomic DNA from adenocarcinomas of the esophagus and stomach for regions of chromosomal imbalance, using comparative genomic hybridization to determine whether tumors at the EGJ (junctional tumors) have a different profile compared with tumors of the distal stomach. Tumor samples were derived from a series of 48 gastroesophageal adenocarcinomas (20 junctional and 28 distal) that were acquired prospectively from patients undergoing esophagogastrectomy. These tumors are characterized by several regions of chromosomal imbalance with no obvious correlation between most regions of abnormal copy number and tumor type. However, our study shows for the first time cytogenetic abnormalities (5p+ and 18q-) that identify statistically significant differences (P < 0.02 and < 0.05, respectively) between junctional and distal gastric tumors. These differences are gain of 5p (55% [11/20] of junctional tumors vs. 21% [6/28] of distal gastric tumors) and loss of 18q (25% [5/20] cases of junctional tumors vs. 4% [1/28] of distal tumors) segregating with tumors of the EGJ. These abnormalities may distinguish distinct tumor subtypes that are recognized in epidemiological and clinical studies but that are otherwise histologically identical.

Postoperative necrotizing fasciitis of the thorax in cardiac surgery

Necrotizing fasciitis is a rare soft tissue infection and a life-threatening emergency, often fatal. Its incidence and management are described plentifully in the medical literature regarding the most common anatomical sites involved like the abdomen, lower and upper limbs, and perineum. However, available data and case reports of chest wall necrotizing fasciitis after thoracic procedures are scarce, mainly after major cardiac operations. We report and discuss a case of necrotizing fasciitis of the chest wall occurring in the immediate postoperative period of a cardiac procedure, and include a brief review of the concepts, pathophysiology, and treatment reported in the medical literature. We emphasize the need for early diagnosis and urgent and effective surgical debridement. Of importance is the fact that we have not found any references in the literature to cases similar or equal to the one we describe here, which occurred in the postoperative period of a cardiac procedure.

Effects of ammonia and amino acids on the growth and proteolytic activity of three species of rumen bacteria: Prevotella albensis, Butyrivibrio fibrisolvens, and Streptococcus bovis

The addition of increasing physiological concentrations of ammonia or amino acids had distinct effects on the growth and proteolytic activity of Streptococcus bovis JB1, Prevotella albensis, and Butyrivibrio fibrisolvens DSM3071. The growth of S. bovis and B. fibrisolvens was enhanced by NH(3) and AA, and that of P. albensis was reduced compared with a control with protein as the sole source of nitrogen. The proteolytic activity of S. bovis and P. albensis was reduced, but that of B. fibrisolvens was improved. NH(3) seemed to act mainly on the cell-associated fraction of the proteolytic activity, while the action of AA was not specific. In the rumen the proteolytic activity of S. bovis and P. albensis would be optimal at low concentrations of NH(3) or AA (<0.05 and <0.27 g/L respectively). In contrast, B. fibrisolvens would need higher concentrations (0.5 g/L of NH(3) or 2.7 g/L of AA). It can be assumed that these bacteria will grow in different ecological niches.

Cloning and characterization of a novel human dual flavin reductase

Flavoprotein reductases play a key role in electron transfer in many physiological processes. We have isolated a cDNA with strong sequence similarities to cytochrome P-450 reductase and nitric-oxide synthase. The cDNA encodes a protein of 597 amino acid residues with a predicted molecular mass of 67 kDa. Northern blot analysis identified a predicted transcript of 3.0 kilobase pairs as well as a larger transcript at 6.0 kilobase pairs, and the gene was mapped to chromosome 9q34.3 by fluorescence in situ hybridization analysis. The amino acid sequence of the protein contained distinct FMN-, FAD-, and NADPH-binding domains, and in order to establish whether the protein contained these cofactors, the coding sequence was expressed in insect cells and purified. Recombinant protein bound FMN, FAD, and NADPH cofactors and exhibited a UV-visible spectrum with absorbance maxima at 380, 460, and 626 nm. The purified enzyme reduced cytochrome c, with apparent K(m) and k(cat) values of 21 microM and 1.3 s(-1), respectively, and metabolized the one-electron acceptors doxorubicin, menadione, and potassium ferricyanide. Immunoblot analysis of fractionated MCF7 cells with antibodies to recombinant NR1 showed that the enzyme is cytoplasmic and highly expressed in a panel of human cancer cell lines, thus indicating that this novel reductase may play a role in the metabolic activation of bioreductive anticancer drugs and other chemicals activated by one-electron reduction.

Cloning and characterization of a novel human olfactory UDP-glucuronosyltransferase

Xenobiotic metabolizing enzymes in the olfactory epithelium have been suggested to catalyse inactivation and facilitate elimination of odorants. We report here the molecular cloning and functional characterization of a human olfactory UDP-glucuronosyltransferase (UGT). The cloned protein is composed of 527 amino acids with an identity of 87% with a rat olfactory UGT and of 43-62% with other human UGT isoforms. Based on the sequence homology, it has been designated hUGT2A1. The gene was mapped to chromosome 4q13 by fluorescence in situ hybridization. The expression appeared to be specific for the olfactory tissue. The substrate specificity of this isoform was assessed using Chinese hamster V79 cells stably transfected with the isolated cDNA. The expressed enzyme showed a broad substrate spectrum including a range of phenolic compounds as well as aliphatic and monoterpenoid alcohols, among them many odorants. Furthermore, some steroids, especially androgens, some drugs and carcinogens were conjugated. The results support a role of the enzyme in olfactory perception and in protection of the neural system against airborne hazardous chemicals.

Library fungi at the University of São Paulo and their relationship with respiratory allergy

In this study, we investigated the fungi most frequently found in the air and the books of 28 libraries at the University of São Paulo, Brazil. In a second phase, 314 librarians were questioned about the presence of asthmatic or rhinitic symptoms, and the relationship with the site of work. Forty-nine percent of them reported this type of symptoms and 80% related them to the place of work. In the third stage, librarians underwent intracutaneous tests against the 20 fungi most frequently isolated in libraries. Eighteen librarians presented positive tests, 12 of whom reported rhinitis and 6 of whom were asymptomatic. In 19.5% of symptomatic patients wheals > 15 mm were observed after 6 h, while 9% of the asymptomatic patients presented similar wheals. Fourteen librarians with positive tests underwent tests with each of the 20 fungi constituting the pool. The airborne fungi isolated in libraries are likely to be found anywhere in the city of São Paulo, but they are likely to be present in higher concentrations in libraries, subsequently producing respiratory allergies.

Health status of older male prisoners: a comprehensive survey

Although prison populations remain predominantly young, the number of older inmates in state and federal correctional facilities has been increasing. This report describes the results of a health survey of 119 male inmates 50 years of age and older residing in Iowa state correctional facilities. Subject's disease history included hypertension (40%), myocardial infarction (19%), and emphysema (18%). Most participants (97%) had missing teeth, 42% had gross physical functional impairments, and 70% smoked cigarettes. These findings have implications for health care provision and release planning.

Major histocompatibility complex modulation of beta-adrenoceptor function

Reciprocal interaction between beta-adrenoceptor specific ligand occupancy and alloantibody binding to specific antigens of cardiac and smooth muscle tissues was observed. Interference of alloimmune antibody fixation to both cardiac and oviductal tract preparations by beta 1 or beta 2 selective blockers, respectively, was obtained by means of indirect immunofluorescence assays. Reciprocally, alloimmune IgG and monoclonal antibodies directed to class I H-2 antigens, behaving as beta-adrenoceptor agonists, modified the contractility of both tissues, increasing intracellular levels of cyclic AMP (cAMP). Additionally, alloantibodies were also capable of inhibiting specific beta-adrenoceptor radioligand binding to purified cardiac and smooth muscle membranes. These data suggested a modulation of beta-adrenoceptor function by antibodies directed against H-2 class I histocompatibility molecules, probably through molecular interactions between both structures.

Health promotion and prevention

Techniques of promotive and preventive health care include: The use of proactive skills in the consultation; and the co-ordinated use of posters and pamphlets with media campaigns. An efficient medical record and patient recall system; and a doctor initiated health check programme with selected patients. A cost effective method of informing practitioners includes: Ensuring access to continuing medical education by supporting FMP and post-graduate medical institutes. The provision of educational material for both the patient and doctor combined with media publicity campaigns. Supporting RACGP CHECKUP and library services for isolated practitioners. Suggested changes to undergraduate medical education are: Promotive and preventive health care delivery needs to be an inbuilt part of the curriculum. Promotive and preventive health care needs to be taught by both academic and private general practitioners who have received tutor training. It should be presented in tutorial form and during student attachment at surgeries. It needs to be followed up by continuing education by postgraduate institutes, the RACGP and FMP. Government input required includes: The provision of increased academic resources and continued funding of FMP. Remuneration for general practitioners who are involved in undergraduate teaching. Alteration of the fee structure to reward quality of care. Allowing Medicare rebate for promotive and preventive health care delivery.

The regulation of the ammonia assimilatory enzymes in Rel+ and Rel- strains of Salmonella typhimurium

The influence of the relA1 mutation on the regulation of the ammonia assimilatory enzymes, glutamate dehydrogenase (EC 1.4.1.4), glutamine synthetase (EC 6.3.1.2), and glutamate synthase (EC 1.4.1.3), was examined. When cells grown in rich media (either Luria broth or glucose-ammonia plus casamino acids) were transferred to a glucose-ammonia medium, the relA mutant failed to resume growth and did not have the same increase in any of the assimilatory enzyme activities as the rel+ strain. This effect was particularly dramatic for glutamate dehydrogenase, which increased 6-fold in the rel+ strain. Measurements of the guanosine nucleotide concentrations showed that the rel+ strain had a ppGpp concentration about 9 times that of the relA mutant 5 min after the shift to minimal medium. These results are consistent with those for other biosynthetic enzymes and show that the ammonia assimilatory enzymes require a relA product for their synthesis during shift from rich to minimal media. In addition, we examined the response of these strains to a change in nitrogen source. The relA mutant again failed to resume growth after a shift from glucose-ammonia to glucose-arginine medium. Even though the ppGpp concentration did not increase, the rel+ strain grew and increased glutamine synthetase activities about 2-fold. These changes the absence of increased ppGpp levels suggest that some other relA-mediated function is important during this change in nitrogen source.