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Biomedical subjects

D Alpers

Publications and source records attributed to D Alpers.

13 recordsLinked to original sources
PubMed2002

Unravelling a biogeographical knot: origin of the 'leapfrog' distribution pattern of Australo-Papuan sooty owls (Strigiformes) and logrunners (Passeriformes).

Molecular analysis of two Australo-Papuan rainforest birds exhibiting correlated 'leapfrog' patterns were used to elucidate the evolutionary origin of this unusual pattern of geographical differentiation. In both sooty owls (Tyto) and logrunners (Orthonyx), phenotypically similar populations occupy widely disjunct areas (central-eastern Australia and upland New Guinea) with a third, highly distinctive population, occurring between them in northeastern Queensland. Two mechanisms have been proposed to explain the origin of leapfrog patterns in avian distributions: recent shared ancestry of terminal populations and unequal rates or phenotypic change among populations. As the former should generate correlated patterns of phenotypic and genetic differentiation, we tested for a sister relationship between populations from New Guinea and central-eastern Australia using nuclear and mitochondrial DNA sequences. The resulting phylogenies not only refute recent ancestry as an explanation for the leapfrog pattern, but provide evidence of vastly different spatio-temporal histories for sooty owls and logrunners within the Australo-Papuan rainforests. This incongruence indicates that the evolutionary processes responsible for generating leapfrog patterns in these co-distributed taxa are complex, possibly involving a combination of selection and drift in sooty owls and convergence or retention of ancestral characteristics in logrunners.

Adenosine Triphosphatases↗
PubMed2002

Reconciling genetic expectations from host specificity with historical population dynamics in an avian brood parasite, Horsfield's Bronze-Cuckoo Chalcites basalis of Australia.

Mitochondrial DNA (mtDNA) is being used increasingly to explore the evolution of host specificity in avian brood parasites. A stable coevolutionary equilibrium between multiple phylogenetically unrelated hosts and a brood parasitic species predicts that mtDNA diversity in the parasite should be relatively deep and phylogenetically structured. Also, the different intraspecific clades resulting from parasitism to multiple sympatric hosts should themselves occur sympatrically. However, mtDNA diversity in brood parasites is as susceptible to effects of historical population dynamics as in any species. We demonstrate the relevance of these dynamics to the use of mtDNA in understanding coevolution between an Australian brood-parasite, Horsfield's Bronze-Cuckoo Chalcites basalis and its hosts, Malurus fairy-wrens and Acanthiza thornbills. Previous ecological and behavioural analyses argue that Malurus- and Acanthiza-specific host races exist in C. basalis. Yet mtDNA diversity in C. basalis is low and phylogenetically unstructured (mean sequence divergence 0.15 +/- 0.07%, range 0.00%-0.31%) and tests of mtDNA neutrality and range expansion vs. population stability (Tajima's D, Fu & Li's F* and D*, Fu's F(S), mismatch analyses) all indicate that C. basalis has expanded its range very recently, probably within the last few tens of thousands of years following climatic amelioration after a peak of aridity in the late Pleistocene. The low mtDNA diversity and its lack of phylogenetic structure in C. basalis deny the existence of evolutionarily long-term stable host races in C. basalis but not the possibility of recently evolved ones. They highlight the need for renewed behavioural and ecological study of the relationship between C. basalis and its hosts. Our findings illustrate the need to understand the evolutionary context in which a brood parasite and its hosts have evolved if mtDNA data are to be used in testing hypotheses concerning the origin and maintenance of host specificity. They also add to the growing body of work illustrating the use of mismatch analyses and Fu's F(S) in detecting range expansions.

Animals↗
PubMed2000

Highly reliable genetic identification of individual northern hairy-nosed wombats from single remotely collected hairs: a feasible censusing method.

The highly endangered northern hairy-nosed wombat (Lasiorhinus krefftii) is extremely difficult to study in the wild, and its numbers correspondingly difficult to estimate. Disturbance to the animals caused by trapping and radio-tracking may not only constitute an excessive risk to the population's viability, but may also yield biased data. The results of a pilot study are presented, which clearly show noninvasive genotyping to be a highly feasible and reliable alternative censusing method for L. krefftii. The protocol can identify individual wombats from single hairs collected remotely at burrow entrances, using: (i) a panel of microsatellite markers giving individual-specific genotypes; and (ii) a Y-linked sexing marker in combination with a single-copy X-linked amplification control. Using just the eight most variable microsatellites (of 20 available), only one in 200 pairs of full-sibs are predicted to share the same genotype. From 12 wombat hair samples collected on tape suspended over burrow entrances, three known female, two known male and an unknown wombat of each sex were identified. The approach will allow censusing of individuals that evade capture, and will also reveal some otherwise problematic aspects of the behaviour of this elusive animal.

Animals↗
PubMed1997

Nutrition support in clinical practice: review of published data and recommendations for future research directions.

In the last 30 years, marked advances in enteral feeding techniques, venous access, and enteral and parenteral nutrient formulations have made it possible to provide nutrition support to almost all patients. Despite the abundant medical literature and widespread use of nutritional therapy, many areas of nutrition support remain controversial. Therefore, the leadership at the National Institutes of Health, The American Society for Parenteral and Enteral Nutrition, and The American Society for Clinical Nutrition convened an advisory committee to perform a critical review of the current medical literature evaluating the clinical use of nutrition support; the goal was to assess our current body of knowledge and to identify the issues that deserve further investigation. The panel was divided into five groups to evaluate the following areas: nutrition assessment, nutrition support in patients with gastrointestinal diseases, nutrition support in wasting diseases, nutrition support in critically ill patients, and perioperative nutrition support. The findings from each group are summarized in this report. This document is not meant to establish practice guidelines for nutrition support. The use of nutritional therapy requires a careful integration of data from pertinent clinical trials, clinical expertise in the illness or injury being treated, clinical expertise in nutritional therapy, and input from the patient and his/her family.

Journal Article↗
PubMed1997

Nutrition support in clinical practice: review of published data and recommendations for future research directions. Summary of a conference sponsored by the National Institutes of Health, American Society for Parenteral and Enteral Nutrition, and American Society for Clinical Nutrition.

In the last 30 years, marked advances in enteral feeding techniques, venous access, and enteral and parenteral nutrient formulations have made it possible to provide nutrition support to almost all patients. Despite the abundant medical literature and widespread use of nutritional therapy, many areas of nutrition support remain controversial. Therefore, the leadership at the National Institutes of Health, The American Society for Parenteral and Enteral Nutrition, and The American Society for Clinical Nutrition convened an advisory committee to perform a critical review of the current medical literature evaluating the clinical use of nutrition support; the goal was to assess our current body of knowledge and to identify the issues that deserve further investigation. The panel was divided into five groups to evaluate the following areas: nutrition assessment, nutrition support in patients with gastrointestinal diseases, nutrition support in wasting diseases, nutrition support in critically ill patients, and perioperative nutrition support. The findings from each group are summarized in this report. This document is not meant to establish practice guidelines for nutrition support. The use of nutritional therapy requires a careful integration of data from pertinent clinical trials, clinical expertise in the illness or injury being treated, clinical expertise in nutritional therapy, and input from the patient and his/her family. (Journal of Parenteral and Enteral Nutrition 21:133-156, 1997).

Cachexia↗
PubMed1991

Rotavirus excretion by village pigs in Papua New Guinea.

Cohort studies were conducted on 29 pigs from 3 villages in the Highlands of Papua New Guinea. Animals ranged in age from 9 d to 5 m old. Three hundred and twenty nine faecal samples were collected from individual pigs followed over 3 to 6 w periods, and were examined for group A rotavirus antigen by ELISA, and rotaviral genomic RNA by polyacrylamide gel electrophoresis (PAGE). Electron microscopy was also conducted on selected samples. Group A rotavirus was detected in the faeces of 16 pigs with infected individuals coming from all villages. Non-group A rotavirus resembling group C was found in faeces from pigs from 2 villages. All of the group A rotaviruses examined had the same electrophoretype and this was distinct from that of the common type infecting humans in the area at the time of the study. None of the group A positive samples reacted with monoclonal antisera specific for human group A rotaviruses of serotypes 1, 2, 3, 4, or 8. The non-group A rotaviruses also all had identical electrophoretypes. In contrast to previous findings in intensive piggeries, rotavirus infection did not occur in all young pigs and was not limited to young animals under 2 m of age. Infected pigs varied in age from 12 days to 20 weeks of age. This pattern of infection was attributed to the non-intensive husbandry situations in the villages, with less opportunity for transmission to occur than in intensive piggeries.

Animal Husbandry↗
PubMed1986

Identifying a limited number of foods important in supplying selected dietary nutrients.

Three methods were developed to identify a limited number of foods that are important dietary contributors of fat, dietary fiber, and vitamins A, C, and E. In the first method, foods were ranked by the amount of each nutrient supplied per person per day and the effect each food had on the relative ranking of individuals with respect to the intake of those nutrients. Foods scoring high on both scales for a given nutrient were selected as important dietary contributors of that nutrient. In the second method, foods were selected according to the mean nutrient contribution per consumer (nonconsumers of a food were eliminated from this estimation procedure). In the third method, foods were selected that contributed a relatively large percentage of the total dietary intake of a given nutrient. The three methods were applied to data from an extensive dietary questionnaire. The authors then compared the limited lists of foods identified by each method. Generally, the methods yielded similar food lists. Regression analysis was then employed to test the ability of the selected foods to predict the nutrient totals calculated from the original, more extensive dietary questionnaire. The results suggest that a limited number of foods may have strong predictive ability, but that has not been tested in any other population.

Aged↗
PubMed1980

Detection of apolipoprotein C in human and rat enterocytes.

Apoproteins have important physiologic functions in lipoprotein metabolism. Several apoproteins are produced in the intestine including ApoA-I, ApoA-IV, and ApoB. Each appears to participate in intestinal lipid transport. The liver also produces several apoproteins, including ApoC-II and ApoC-III, but the data demonstrating the ability of the intestine to produce ApoC is incomplete. Our aim was to ascertain whether ApoC-II and ApoC-III were present in human and rat jejunum, and if so, whether their presence was altered by fat feeding. The technique of immunolocalization and a newly developed double antibody radioimmunoassay for rat ApoC-III3 were used. ApoC-III3 was found in the supranuclear regions of enterocytes along the entire lengths of villi in the jejuna of 12-h-fasted rats. 1 hour after the gastric ingestion of corn oil. ApoC-III3 was found primarily in between cells and in the lamina propria. Similar results were obtained in human jejunal biopsies with ApoC-II and ApoC-III. ApoC-III3 was also detected by radioimmunoassay in enterocytes isolated from jejuna of neonatal and adult rats. Thus, ApoC-II and ApoC-III are clearly present in the intestine as well as in the liver. In addition, because their localization is altered after fat feeding, they are also likely to be produced in the enterocyte.

Animals↗
PubMed1978

Inflammatory bowel disease (ulcerative colitis).

There is uncertainty as to the proper management of a patient with chronic ulcerative colitis who has had his disease for over ten years but has not been sufficiently symptomatic to warrant colectomy. Not all patients are at high risk to develop cancer. Wide extent and long duration of disease are correlated with increased risk. The ability to define a patient at risk beyond these single criteria are very limited. The definition and efficacy of the precancerous lesion observed in rectal biopsies is still a matter of dispute, and the routine use of proctocolectomy for patients with long-standing colitis is still not universally accepted. Careful follow-up is obviously indicated, but it is still uncertain whether roentgenography, colonoscopy, colonic biopsy, or a combination of these methods will ultimately prove the procedure of choice.

Adult↗
PubMedDate not supplied

Nutrition support in clinical practice: review of published data and recommendations for future research directions. National Institutes of Health, American Society for Parenteral and Enteral Nutrition, and American Society for Clinical Nutrition.

In the last 30 years, marked advances in enteral feeding techniques, venous access, and enteral and parenteral nutrient formulations have made it possible to provide nutrition support to almost all patients. Despite the abundant medical literature and widespread use of nutritional therapy, many areas of nutrition support remain controversial. Therefore, the leadership at the National Institutes of Health, The American Society for Parenteral and Enteral Nutrition, and The American Society for Clinical Nutrition convened an advisory committee to perform a critical review of the current medical literature evaluating the clinical use of nutrition support; the goal was to assess our current body of knowledge and to identify the issues that deserve further investigation. The panel was divided into five groups to evaluate the following areas: nutrition assessment, nutrition support in patients with gastrointestinal diseases, nutrition support in wasting diseases, nutrition support in critically ill patients, and perioperative nutrition support. The findings from each group are summarized in this report. This document is not meant to establish practice guidelines for nutrition support. The use of nutritional therapy requires a careful integration of data from pertinent clinical trials, clinical expertise in the illness or injury being treated, clinical expertise in nutritional therapy, and input from the patient and his/her family.

Humans↗