Mars Extant Life: What's Next? Conference Report.

On November 5-8, 2019, the "Mars Extant Life: What's Next?" conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia ("oases"), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order): Caves, Deep Subsurface, Ices, and Salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, but instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). Again, it was not within the scope of the conference to prioritize these measurement techniques-that is best left for the competitive process. We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceed the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories and analog field sites and from theoretical modeling.

Shiga-like toxin-producing Escherichia coli O111 and associated hemolytic-uremic syndrome: a family outbreak.

OBJECTIVE: To describe a family cluster of Shiga toxin-producing Escherichia coli O111ac:NM infection. STUDY DESIGN: The index case was identified as part of a United States prospective study of hemolytic-uremic syndrome. Epidemiologic investigation was conducted through interviews. E. coli O111:NM infection was characterized through culture and serology. Shiga toxin 1 and 2 gene sequences were determined with oligonucleotide DNA probes. RESULTS: All three children and both parents had nonbloody diarrhea, vomiting and abdominal cramps, and one child developed hemolytic-uremic syndrome. Shiga toxin 1- and 2-producing E. coli O111ac:NM was isolated from two children. IgG antibodies to E. coli O111 were detected in all three children. CONCLUSIONS: To our knowledge this is the first reported cluster of O111 infection and only the second caused by non-O157 Shiga toxin-producing E. coli in North America.

Acute effect of high-calcium milk with or without additional magnesium, or calcium phosphate on parathyroid hormone and biochemical markers of bone resorption.

OBJECTIVE: To assess whether there are any differences in the postprandial physiological responses to apple drink (control), calcium phosphate (tricalcium phosphate, TCP) and high-calcium skim milk (HCSM) with or without additional magnesium in postmenopausal women. DESIGN: Randomized, controlled, cross-over. Measurements after overnight fast before each drink, and subsequently every hour for 8 h postprandially. SETTING: Human Nutrition Studies Laboratory, Milk and Health Research Centre, Massey University, Palmerston North, New Zealand. SUBJECTS: Twenty-one healthy postmenopausal women. INTERVENTION: Four drinks, each 400 ml. (1) Apple drink (25% fruit juice). (2) TCP dispersed in water containing 1200 mg Ca. (3) HCSM containing 1200 mg Ca and 65.5 mg Mg. (4) HCSM containing 1200 mg Ca and 172 mg Mg. RESULTS: There was no difference in baseline serum calcium, PTH or C-telopeptide levels between drinks. There were no overall differences in serum calcium after apple or after either milk, but after TCP serum calcium increased from a baseline value of 2.12+/-0.08 to a mean peak of 2.21+/-0.12 mmol/l (s.d.) (P=0.0001) after 2 h. There were no significant differences in serum PTH after either apple or HCSM+Mg. In contrast, after TCP, serum PTH decreased from 2.76+/-0.69 to a mean nadir of 2.23+/-0.65 pmol/l (P=0.0001) after 1 h, and after HCSM, it decreased from 2.71+/-0.78 to a mean nadir of 2.51+/-0.87 pmol/l (P=0.007) after 2 h. Serum C-telopeptides decreased after each drink, reaching nadirs after 5 h. At this time the serum values for each of the high calcium drinks were not different from each other, but were significantly less than for apple (P=0.001 for each), being 0.22+/-0.09 ng/ml for apple, 0.15+/-0.08 for TCP, 0.14+/-0.07 for HCSM and 0.16+/-0.07 for HCSM+Mg. CONCLUSION: Despite differences in serum calcium and PTH responses to the three high-calcium drinks that we tested, there was no distinguishable difference in serum C-telopeptides between high calcium drinks.

Nutritional management of patients with short-bowel syndrome.

The healthy small intestine plays a vital role in the absorption of fluid, electrolytes, and nutrients. This function is severely compromised after surgical resection, although the remaining gut has a large capacity for adaptation. The nature of the nutritional support offered to patients with short-bowel syndrome depends on the length and site of small intestine resected, time after surgery, underlying disease, and nutritional status of the patient. If sufficient gut remains, oral supplementation is the treatment of choice, but attention must be given to potential malabsorption, particularly of micronutrients. Oral feeding is perhaps the most important means of promoting intestinal adaptation, which can be much delayed. Inevitably, some patients will not be able to tolerate or thrive on oral nutrition, and these few may need to resort to intravenous feeding support. This approach is often considerably challenging and should be managed only by those with expertise, because numerous and sometimes significant difficulties can be encountered.

Back pain in childhood.

Sixty-one children with back pain presented to the authors' department between 1978 and 1984, accounting for less than 2% of referrals in this age group. Approximately 50% had serious spinal disease, yet clinical findings could be unreliable in distinguishing such patients. In the absence of compelling physical signs, children with normal radiographs, white cell count, and sedimentation rate can be treated symptomatically and observed for some months before more invasive investigations are considered.

Slipped upper femoral epiphysis after radiotherapy.

Eight slipped upper femoral epiphyses in patients who had had radiotherapy are described. These cases involved five patients in an "at risk" population of 48. This increased incidence is highly significant.

Heart rate and oxygen consumption during walking on land and in deep water.

Oxygen consumption and heart rate were measured during treadmill walking and during walking in deep water in a group of women and in a group of men. In both groups predicted maximum oxygen uptakes were similar on land as in the water. However, there were obvious individual differences in the responses to land versus water exercise. These differences suggest that if deep water walking is used for training, the intensity of work should be assessed from preliminary fitness tests in water and not on land.

Correlations between biochemical markers of bone resorption and creatinine excretion.

There were two reasons for doing this study. The first was to assess whether expressing biochemical markers of bone resorption as a ratio to creatinine excretion influences the correlations between them. The second was to assess whether biochemical markers of bone resorption are correlated with creatinine excretion, which is a biomarker of muscle mass. Three biochemical markers of bone resorption, free deoxypyridinoline (DPD), N-telopeptides (NTx) and C-telopeptides (CTx), together with creatinine (cr), were measured in 24-h urine samples of 45 healthy people (26 women and 19 men). The urinary concentrations of DPD, NTx and CTx were highly correlated with each other. These relationships were weakened, or no longer statistically significant, when the markers were expressed as a ratio to cr excretion. The 24-h excretion of each of the markers was correlated with 24-h cr excretion in men, but only 24-h DPD was correlated with 24-h cr excretion in the women. The men had significantly higher 24-h excretion rates of each of the markers than the women did. Since muscle mass is related to skeletal mass, these data suggest that in healthy people the rate of bone resorption may be a function of skeletal size as well as the rate of bone turnover. For small human studies 24-h urine sampling is recommended in preference to untimed sampling. However, for clinical purposes, or for large clinical trials, this may not be practical.

Frequent rehospitalization and noncompliance with treatment.

The relationship between frequent rehospitalization and compliance with treatment (medication and aftercare) was examined in a retrospective chart review of patients treated at an urban community mental health center over an 18-month period. Twenty-five patients who had been hospitalized three or more times during the study period were compared with a matched group of 25 patients who had been hospitalized less than three times and with the total group of 698 patients active at the center throughout that period. The study found a highly significant correlation between noncompliance with medication and frequent rehospitalization. Compared with the general psychiatric patient population, frequently hospitalized patients tended to be younger and to have a chronic psychiatric illness, particularly one with an affective component, that featured at least intermittent psychosis. The author recommends study of outpatient commitment to treatment as a means of reducing noncompliance.

Long-term home care research.

The population of seniors is growing and health service reimbursement is shrinking. Long-term home health care services were developed with an assumption that the services would decrease costs. This assumption has not been validated. What has been recognized is that long-term home health care targets a new and growing population of frail seniors who need services but are probably not at risk for institutionalization. The impact of long-term home care services on the health status and quality of life of seniors and caregivers has been limited by outcome measurement problems. There are indications that the services improved life satisfaction and reduced services needs, but further evaluations need to replicate the outcomes. In effect, long-term outcomes have not been sufficiently explored. Further research also needs to assist us in identifying outcomes for certain services with precise target populations. Public policy questions are ahead. Should a program that can increase costs, has demonstrated some but not dramatic impacts on quality of life and health status, and has the possibility of expansion, be funded? The question is obviously debatable. From a nursing perspective of health promotion and prevention, the answer is "yes." Funding should be continued in conjunction with increased research on the program impacts. In Kane's (1988) analysis of the Channeling experiments, she summarized the situation effectively: Knowing these facts, we are now in a position to reformulate public policies to design a system of long-term care that satisfies the preferences of consumers and protects them from catastrophic long-term expenses, while promoting the triple virtues of acceptable, quality, equitable access, and defensible costs. . . Nothing in the Channeling results should prevent us from going ahead and trying to develop both community based and institutionally based long-term services in which this country can take pride.

The thermic effect of food in underweight patients with emphysematous chronic obstructive pulmonary disease.

Malnutrition and weight loss commonly occur in patients with the emphysematous type of chronic obstructive pulmonary disease (COPD), despite normal energy intakes. The present study was designed to assess energy expenditure, basal metabolic rate (BMR) and diet-induced thermogenesis (DIT) in ten patients with COPD, together with the oxidation rates of carbohydrate, protein and fat. The BMR was elevated when tested against the Harris-Benedict equation (p less than 0.001) or when compared with six age- and sex-matched controls (11.11 +/- 2.52 vs 8.12 +/- 1.31 kJ.h-1.kg muscle-1, p less than 0.05). The main difference in fuel oxidation rate was an elevated fasting fat oxidation rate in the patients compared with controls (8.31 +/- 3.09 vs 4.76 +/- 2.53 kJ.h-1.kg muscle-1, p less than 0.05). The overall thermic response to food (41.2 kJ.kg-1 liquid meal) as a percentage of energy intake was greater in the patients (49.5 +/- 6.3 vs 39.8 +/- 2.9%, p less than 0.01). The patients also displayed a greater post-prandial rate of protein oxidation as a percentage of protein intake than controls (56.9 +/- 18.5 vs 34.1 +/- 6.5%, p less than 0.05). These data suggest an increased energy cost of feeding and fasting in patients with the emphysematous type of COPD.

The influence of intravenous glucose on body temperature.

The influence of an intravenous infusion of glucose (500 ml of 20% w/v), on heat production and variables which contribute to heat loss was studied in six normal human volunteers. Mannitol (500 ml of 20% w/v) was infused on a different occasion as an osmotic control. Both infusions produced changes in haematocrit and osmolality of a similar magnitude. Heat production increased by 20% after intravenous glucose but only a small increase in heat production was observed after intravenous mannitol. Calf blood flow increased after both infusions but hand blood flow increased only after the glucose infusions. The increase in skin temperature which was observed after both infusions was associated with increases in peripheral blood flow. Core temperature decreased slightly following administration of both substances. The changes in metabolic heat production and cardiovascular function are discussed. These changes do not appear to be due to the catecholamine response to hyperglycaemia and hyperosmolality.

Weight loss in chronic obstructive pulmonary disease.

Weight loss occurs in about a third or more disabled patients with chronic obstructive pulmonary disease (COPD), and appears to be a poor prognostic factor. As such, it correlates only weakly with FEV1, transfer factor and other measures of respiratory physiology and is probably, to a certain extent, independent of them. Recent studies of basal metabolic rate (BMR) in COPD using steady-state, non-invasive calorimetry, have shown it to be elevated by 10-20% in up to 40% of such patients. It is likely that this represents true hypermetabolism per kilogram of fat free mass. An elevated BMR cannot be predicted from combinations of detailed lung function tests or arterial gases, as patients with similar physiology have differing BMRs. Thus, although an increased work of breathing is the probable explanation for some of the increase, other factors such as cytokines or possibly drug therapy almost certainly contribute. Muscle loss in weight-losing COPD appears to involve both type I and type II fibres, because of a combination of reduced calorie intake and disuse atrophy. Respiratory muscles share this fibre loss. Review of the controlled studies on nutritional supplementation in COPD suggests that an energy increase of about 30% is needed to achieve substantial weight gain and improve exercise tolerance. Fat-rich supplements have some theoretical advantages. Further work is needed particularly with regard to the determinants of the increased BMR in COPD, and the effect of longer term nutritional supplements on prognosis.