Search PubMed⌕ Search

Biomedical subjects

J Ernst

Publications and source records attributed to J Ernst.

At least 109 records · Page 6Linked to original sources
PubMed1989

The post-antibiotic effect defined by bacterial morphology.

Three strains of Escherichia coli were incubated with either ciprofloxacin or ampicillin. Filamentation of bacteria was observed after 1-2 h. After 5 h of contact with either drug the percentage of filaments exceeded 90%. The organisms were washed and incubated on drug free medium. Antibiotics when bound to an enzyme render that enzyme inactive; upon removal of the organisms from the antibiotic, the synthesis of enzymes resumes. The period of time encompassing the inactive enzymatic state of the organism at the time of removal from the drug to the time that enzymes restore complete function is our definition of the post-antibiotic effect (pae). Bacterial morphology reflects the variations in activity of these enzymes. The pae was determined by both the morphology of the organisms and the current growth kinetic method. The presence of 10% filaments and 90% bacilli was selected to indicate the endpoint of the pae by morphological criteria. The pae by morphology was 4 h for ciprofloxacin and 3 h for ampicillin. By the growth kinetics method it was 2 h for ciprofloxacin and zero for ampicillin.

Ampicillin↗
PubMed1989

Absorption of calcium and magnesium from fortified human milk by very low birth weight infants.

Absorption of calcium and magnesium endogenous to human milk, as well as calcium and magnesium added as an exogenous supplement to human milk, was determined in 9 very low birth wt infants. Human milk, intrinsically labeled with stable isotopic tracers of calcium and magnesium, was prepared by administering isotopic tracers intravenously to a lactating woman. Different isotopic tracers, which were representative of calcium and magnesium in the supplement (Enfamil Human Milk Fortifier, Mead Johnson Nutritional Div.), were added to the intrinsically labeled milk. The fortified milk, which was labeled with two calcium tracers and two magnesium tracers, was given orally to the test subjects in a single feeding. True absorption of calcium and magnesium was determined from differences between the doses of tracer ingested and the quantities of tracer excreted in the feces. Stable isotopic tracers were quantified by fast atom bombardment mass spectrometry. These results demonstrate that the fractional absorptions of calcium in the human milk and the added mineral supplement are 80 and 82%, respectively. A total of 89% magnesium endogenous to human milk and 86% of magnesium derived from the mineral supplement was absorbed by the VLBW infants.

Biological Availability↗
PubMed1989

Methods to evaluate the wellbeing of laboratory primates: comparisons of macaques and tamarins.

Three objective behavioral tests are described for the assessment of wellbeing and possible enrichment of laboratory primates. One test, foraging for food in a pickup tray, proved practical for both macaques and tamarins. It provides positive human interaction as well as standardized evaluation of appetite for food and sensory-motor coordination. A puzzle feeder provided more complex foraging which could be performed by macaques, but not by tamarins. A third noninvasive test, used only with macaques, measured daily energy expenditure and sleep-wakefulness cycles as expressed in the diurnal rhythm of homecage activity. Normative data indicate the usefulness of each. Further refinement and validation of new tests and enrichment strategies requires a major research effort. Definitive measures such as those described here, coupled with data on long-term health outcomes, are essential before regulations for primate care can be revised with confidence.

Animal Welfare↗
PubMed1988

Activity of amikacin and ampicillin in succession and in combination.

One strain each of Escherichia coli and Streptococcus faecalis were exposed to amikacin and ampicillin in combination as well as in succession. Exposure to ampicillin for 1 hr followed by amikacin for 3 or 4 hr had the greatest antibacterial activity when the antibiotics were applied in succession. The least effective exposures for both organisms were 1 hr to amikacin followed by 3 or 4 hr to ampicillin. Exposure to the antibiotics in combination each at 1 MIC had the overall greatest antibacterial activity. Simultaneous exposure to the antibiotic combination does not necessarily mean simultaneous activity of both ampicillin and amikacin on the E. coli. The cell wall autolytic activities produced by ampicillin are triggered within 10 min after physical contact with the bacteria. In contrast, amikacin requires at least 30 min after physical contact to manifest its activity on the ribosome. Although physical exposure to both antibiotics in the combination is simultaneous, the specific activity of each is in fact sequential, with ampicillin acting first. This explains the synergistic effect of the combination. It appears, therefore, that the synergistic or antagonistic affect of a drug combination is determined by the sequence and timing of the antibacterial manifestations of its components.

Amikacin↗
PubMed1987

Neuropsychological problem-solving skills in the elderly.

This article describes the performance of a representative sample of 110 participants aged from 65 to 75 years. Participants completed the Trail-Making Test, Tactual Performance Test, and Booklet Category Test. Results confirmed that previously established cutoff scores used to determine impairment are not appropriate for this age group. Significant sex differences were found for the Tactual Performance Test and Booklet Category Test. Mean scores presented in this article provide useful normative standards for the three aforementioned tasks when given to patients aged from 65 to 75 years.

Aged↗
PubMed1987

Relationships between IQ and neuropsychological measures in neuropsychiatric populations: within-laboratory and cross-cultural replications using WAIS and WAIS-R.

Several studies have reported positive correlations between measures of intelligence (a quasi-subject variable) and level of performance on neuropsychological tests; few, however, have presented test results by IQ grouping, which could be useful for comparative purposes. The present study examined the relationships of WAIS and WAIS-R Full Scale IQ to performance on a neuropsychological battery consisting of the Halstead-Reitan Battery (HRB), the Wide Range Achievement Test (WRAT), and the Wechsler Memory Scale (WMS). Four mixed neuropsychiatric samples provided cross-cultural and within-laboratory replications, two tested with WAIS and two with WAIS-R. Means and standard deviations for each measure were presented by five IQ levels within each sample. IQ was strongly related to scores on problem-solving tasks, auditory and linguistic measures, memory tasks, academic achievement levels, and tactual imperceptions, while motor functioning and sensory suppressions were less strongly related to IQ. IQ level was related to educational level in all samples. Correlations of years of education with dependent variables in the two WAIS-R samples were strong and replicable for WRAT scores, verbal memory measures, linguistic errors on the Aphasia Screening Test, and finger-tapping speeds but not for other HRB measures. Finally, IQ-HRB relationships were compared to those reported for other populations.

Achievement↗
PubMed1987

Age group differences on neuropsychological battery performance in a neuropsychiatric population: an international descriptive study with replications.

The relationship of age to performance on the Halstead-Reitan Neuropsychological Battery was examined in three samples drawn from neuropsychiatric populations: an initial sample of 217 subjects, a within-laboratory replication of 307 subjects, and a cross-national replication sample of 101 subjects. The results showed significant relationships of age to subtests of the Halstead-Reitan Battery involving problem-solving abilities and motor strength, which were replicated across the three samples. Verbal and perceptual subtests were not consistently related to age across samples. For those problem-solving and motor tests showing replicated correlations with age. mean scores are provided for three age groups (16-34, 35-54, and 55 and above), and group differences were tested with analysis of variance. These results help clarify for which measures age group differences are consistent in neuropsychiatric populations. Implications of these results for treatment program planning are discussed

Journal Article↗
PubMed1987

Effects of antibiotics on bacterial structure and their pathogenicity.

Subinhibitory concentrations of beta-lactam antibiotics as well as some other antibacterial agents alter the ultrastructure of bacteria. The separation of replicated genomes of Gram positive cocci is inhibited, and results in clusters of as many as 30 organisms held together by thick cross walls. The separation of the replicated genomes of Gram negative bacilli is also inhibited and results in the formation filaments. These altered forms of bacteria usually exhibit lower pathogenicity than their respective normal counterparts such as; decreased adherence to epithelial cells, higher susceptibility to phagocytosis and decreased output of bacterial enzymes. Contrary to common belief, subinhibitory concentrations do not generate a significant increase in bacterial resistance to the respective drug.

Animals↗
PubMed1986

Factor analysis of the Wechsler Memory Scale: is the associate learning subtest an unclear measure?

A factor analysis of the Wechsler Memory Scale (WMS) with 30-minute delayed recall scores (percent retained) for the Logical Memory, Visual Reproduction, and Associate Learning subtests indicated that this variant of the WMS taps different types of learning and memory for new material. With regard to the verbal learning/recall subtests, Logical Memory appears to be related to attention/ concentration ability, while Associate Learning is relatively independent. The results also showed that both the easy and hard items from Associate Learning tap the same ability, providing evidence that this subtest is a measure of rote verbal learning. These results support the clinical utility of the WMS with delayed recalls in neuropsychiatric populations.

Journal Article↗
PubMed1986

Nitrogen sources for parenteral nutrition in the newborn infant.

Protein requirements for the preterm and term infant have been determined by a variety of methods. The parenteral protein needs of the very low birth weight infant are around 3 gm/kg/day and of the term infant approximately 2.2 gm/kg/day for maintenance of normal growth. These values are averages and may need to be modified for individuals depending upon a variety of potentially complicating factors. In this regard, many neonatologists recommend the provision of a maximum of 2 to 2.5 gm/kg/day of protein to newborns under most clinical situations. Whereas excessive administration of protein may result in adverse consequences, the tolerance of young infants to infusion of amino acid solutions is not well defined. Based upon animal studies of fetal amino acid utilization, the preterm infant may be capable of appropriately modifying its supply of amino acids over a relatively broad concentration range. It would appear that the supply of individual amino acids is adequately met by a number of amino acid solutions. The newer preparations appear to be more ideally suited to the special needs of the very low birth weight.

Amino Acids↗
PubMed1985

Ultrastructure of staphylococci in respiratory infections treated with nafcillin.

A patient with a pleural effusion containing Staphylococcus aureus was treated with nafcillin. Another patient with bilateral upper lobe infiltrates which grew S. aureus from a catheter inserted through a fiberoptic bronchoscope into the lesion was also treated with nafcillin. Electron microscopy of organisms grown while the patients were receiving nafcillin showed staphylococci which were twice as large as normal and contained multiple cross-walls and normal peripheral cell walls. Such abnormal staphylococci result from exposure to subminimum inhibitory concentrations of beta-lactam antibiotics.

Adult↗
PubMed1981

Sickle cell trait and glucose-6-phosphate dehydrogenase deficiency. Effects on health and military performance in black Navy enlistees.

The purpose of this longitudinal study was to compare the Navy performance and health status during a four-year enlistment of four subsamples of black enlistees who began active service between Feb 14 through Sept 15, 1972. On the basis of results obtained from screening procedures for hemoglobinopathies, a sample of 8,725 enlistees was separated into four subgroups: 599 subjects with sickle cell trait, 1,003 subjects with glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, 73 subjects with both trait anomalies, and 7,050 normal subjects. Results of comparative analyses indicated that the three trait subsamples did not differ significantly from the normal group on demographic and service-related variables, seven performance criteria, hospitalization rates, or mortality. Thus, the trait anomalies studied were found to be benign under routine conditions of naval service.

Anemia, Sickle Cell↗