Biomedical subjects

J K Miller

Publications and source records attributed to J K Miller.

At least 55 records · Page 3Linked to original sources

PubMed1990

Patterns of organellar and nuclear inheritance among progeny of two geographically isolated strains of Volvox carteri.

Strains of Volvox carteri forma nagariensis derived from Japanese and Indian isolates ("J" and "I" strains, respectively) exhibited length differences (RFLPs) for approximately 90% of the restriction fragments detected by hybridization with a variety of unique-sequence, small-gene-family and repetitive-element probes, including heterologous probes of chloroplast and mitochondrial origin. Extensive post-zygotic mortality was observed among the zygotes produced by crossing J and I strains, suggesting some form of genetic incompatability between them. Most of the viable progeny exhibited recombinant patterns of nuclear inheritance and maternal inheritance of mitochondrial and chloroplast markers. However, many progeny exhibited exclusively uniparental (usually maternal, but in one case paternal) inheritance of both nuclear and organellar markers. Some of these non-recombinant individuals may be derived from "parthenospores" (dormant asexual cells resembling zygospores). Others may be a result of "pseudogamy," in which one of the parental pronuclei is excluded from the zygote, followed by selective exclusion of both the mitochondrial and the chloroplast genomes derived from that same parent. When segregation patterns for 44 nuclear markers were analyzed in 90 recombinant progeny, statistically significant, locus-specific deviations from expected Mendelian transmission ratios were observed for a sizeable fraction of all markers in both reciprocal crosses: some markers were preferentially transmitted by the J strain, while others were preferentially transmitted by the I strain. It is speculated that these transmission distortions may be related to the regions of inter-isolate genetic incompatibility, and may complicate the use of J x I crosses to establish a RFLP-based linkage map for the species.

Animals↗

PubMed1990

Effects of hypomagnesemia on reactivity of bovine and ovine platelets: possible relevance to infantile apnea and sudden infant death syndrome.

Blood platelet function and possible involvement in death of hypomagnesemic ruminants was investigated with 26 Angus cows, 15 mature Hampshire wethers, eight Finnish-Hampshire ewes, and 36 growing Dorset lambs. Hypomagnesemia was induced by feeding vegetative spring tall fescue to 13 cows and semipurified diets low in Mg to nine wethers, four ewes, and 18 lambs. In comparison with controls, dietary treatments reduced plasma Mg concentrations 55% in cows, 36% in wethers, 66% in ewes, and 78% in lambs. Hypomagnesemia reduced in vitro reactivity of cow and lamb platelets to thrombin, ADP, and platelet active collagen, but in vitro tests may not accurately reflect in vivo platelet reactivity. Microscopic examination of platelet-rich plasma revealed a threefold increase in clumped platelets from four hypomagnesemic ewes compared to four normomagnesemic ewes. This suggests that in vivo activation and exhaustion of platelets may have contributed to reduced in vitro platelet reactivity. Six of 18 hypomagnesemic lambs died spontaneously in tetany after 2-12 months on low-Mg diets. Heart and lung lesions were markedly similar to pathological changes induced in other lambs by intravascular activation of platelets with 500 micrograms of vascular collagen fibrils per kg body weight injected intravenously. These results suggest the possibility of abnormal blood platelet activation as a significant mortality risk factor in severe hypomagnesemia.

Animals↗

PubMed1990

The sharp theta rhythm on the occipital areas of prematures (STOP): a newly described waveform.

This study on 500 prematures and neonates with conceptional ages (CA) of 23-49 wks describes the STOP pattern (sharp theta on the occipitals of prematures). STOP is similar to PT theta (premature temporal theta) in configuration, but is faster in frequency, lower in amplitude, more often unilateral, aside from the obvious difference in location. The incidence (%) was highest at the youngest age, decreasing to zero near term, and the amount (number of bursts) was greatest at 25 wks (CA). Three different parts appear in the incidence and amplitude curves, and these three parts may be related to changes in the laterality of the pattern. In the youngest age these rhythms are mainly bilateral, in the older neonates they are unilateral and are either for the ages between those extremes. STOP is seen more often in active sleep, but is reduced in incidence in patients with abnormal slow waves, ictal or immature patterns. Right-sided STOP was more frequently associated with abnormal EEGs, especially in males with right-sided sharp waves, often noted in the patients with seizures and intraventricular hemorrhages.

Electroencephalography↗

PubMed1990

Iodine in milk and meat of dairy cows fed different amounts of potassium iodide or ethylenediamine dihydroiodide.

Relationships between I intake by lactating Holstein cows and iodine concentrations in milk and meat were investigated. Six treatment groups with seven cows assigned to each treatment were fed a basal diet containing .8 mg I/kg alone or supplemented with I at 1, 2, or 4 mg/kg in four 5-wk periods. Basal alone was fed in the first and third periods and the I supplement was potassium iodide in the second period and ethylenediamine dihydroiodide in the fourth period. Iodine concentrations in milk increased with each increase in dietary I from 205 ng/ml for basal periods to 404, 477, and 757 ng/ml when 1, 2, or 4 mg/kg I was fed as potassium iodide; and 467, 535, and 869 ng/ml when 1, 2, or 4 mg/kg I was fed as ethylenediamine dihydroiodide. Concentrations of I in skeletal muscle after the fourth period were not affected by 2 mg/kg I and only increased from 166 to 199 ng/g when supplemental I was 4 mg/kg. Moderate changes in dietary I are quickly reflected in milk I, but I in meat is relatively stable.

Animals↗

PubMed1990

Effect of magnesium administration route on plasma minerals in Holstein calves receiving either adequate or insufficient magnesium in their diets.

Rates of increase in plasma Mg following rectal or oral administration of solutions containing 30 g MgCl2.6H2O were compared in 10 Holstein bull calves receiving wheat straw (.07% Mg) and concentrates (.04 or .24% Mg) fed separately for ad libitum consumption. Treatments were administered in a sequence, which involved each calf with all combinations of MgCl2.6H2O dosing routes and dietary Mg within a 6-wk period. Plasma Mg concentration averaged 1.95 mg/dl initially but fell below 1 mg/dl within 2 wk after supplemental Mg was omitted. Maximum increases in plasma Mg concentration following oral or rectal dosing were 16 or 47% when dietary Mg was adequate and 48 or 124% when Mg was deficient. Calves fed either diet responded maximally to rectal infusion within 10 min, but plasma Mg of deficient calves increased throughout 160 min after oral dosing. Plasma Mg of deficient calves responded quicker and reached higher concentrations after rectal infusion, but the response was sustained longer after oral administration.

Administration, Oral↗

PubMed1989

Importance of heterosexual activity in the transmission of hepatitis B and non-A, non-B hepatitis.

To identify previously unrecognized sources for acquiring acute hepatitis B and non-A, non-B (NANB) hepatitis, we interviewed patients with these types of hepatitis who were reported to two county health departments in the United States and matched control subjects for known and potential risk factors for acquiring hepatitis. Of 218 patients with hepatitis B and 140 patients with NANB hepatitis, 46% and 53%, respectively, had no commonly recognized source for infection. When these patients were compared with control subjects, significantly more patients with hepatitis B had multiple heterosexual partners, accounting for 14% of all hepatitis B infections; more patients with NANB hepatitis either had sexual or household contact with a person who had hepatitis in the past or had multiple heterosexual partners, accounting for 11% of all NANB infections. This is the first study to suggest that heterosexual transmission may play an important role in the spread of NANB hepatitis.

Adult↗

PubMed1989

Influence of uvrB and pKM101 on the spectrum of spontaneous, UV- and gamma-ray-induced base substitutions that revert hisG46 in Salmonella typhimurium.

Oligonucleotide probes were used to identify base substitutions in 1089 revertants of hisG46 in Salmonella typhimurium that arose spontaneously or following irradiation with UV- or gamma-rays. The hisG46 allele, carrying a mutant CCC codon (Pro) in place of the wild-type codon CTC (Leu69) reverted via 6 distinguishable mutational events--C to T transitions at codon sites 1 or 2, C to A or C to G transversions at codon site 1, C to A at codon site 2, and an extragenic suppressor mutation. The distribution of hisG46 revertants differed among treatments and was influenced by the DNA-repair capacity of the bacteria. Plasmid pKM101 enhanced the frequencies of both spontaneous and induced mutations; transversion events were enhanced more efficiently by pKM101 than were transition events. Compared to Uvr+ bacteria, Uvr- bacteria had higher frequencies of spontaneous and induced mutations; transition mutations were enhanced more efficiently than were transversion mutations. The influence of DNA-repair activities on the mutational spectra provides some insights on the origins of spontaneous and UV-induced mutations.

DNA Damage↗

PubMed1989

The pharmacodynamics of diphenhydramine-induced drowsiness and changes in mental performance.

The time course of diphenhydramine concentrations and effects on both mental performance and subjective feelings of drowsiness were assessed in 15 healthy men. Subjects received single oral doses of diphenhydramine, 50 mg, and placebo in this double-blind crossover study. Diphenhydramine plasma concentrations and central nervous system actions were assessed for 24 hours after each treatment. Cognitive impairment was assessed with an automobile driving simulator and digit symbol substitution scores, whereas drowsiness was self-assessed on a visual analog scale. Diphenhydramine produced significant feelings of drowsiness for up to 6 hours after the dose, whereas significant mental impairment was apparent for only 2 hours. Despite the difference in duration of these effects, drowsiness and mental impairment have parallel slopes when effects are related to diphenhydramine concentrations. These data suggest that although the apparent diphenhydramine concentration thresholds to produce drowsiness are lower (30.4 to 41.5 ng/ml) than those needed to produce mental impairment (58.2 to 74.4 ng/ml), these effects have profiles consistent with their being manifestations of the same pharmacologic effect.

Adult↗

PubMed1989

An example of the possible clinical usefulness of topographic EEG displays.

This paper shows the brain maps of a patient before and during a seizure initiated by a focus within the right occipital area. The maps demonstrate an ictal transformation in the form of a gradual decrease in frequency of the ictal rhythms, seen also on the EEG traces. However, the maps also show the very distinct difference in the background activity between the left and right hemispheres, and also the possibility of independent foci of depressed activity within the right anterior and posterior temporal areas, the latter not at all evident on the EEG tracings. This case may serve as an example of useful data gathered on a patient by EEG topography, not made clear by a standard recording.

Adolescent↗

PubMed1989

Response of lactating jersey cows fed concentrate twice daily by computer or in a total mixed ration.

Two trials were conducted with 36 Jersey cows each to compare intake, production response, and relative economics of four concentrate management systems. Cows were assigned for 25 wk to concentrate fed: 1) for ad libitum consumption twice daily for 10 min, 2) twice daily according to production, 3) via computer feeder according to production, or 4) as part of a total mixed ration. Concentrate was fed at the rate of 1 kg/3.5 kg 4% FCM for treatments 2 and 3 and at the same rate, but to group average FCM, for treatment 4. Concentrate allotments were updated weekly. Cows were individually fed blended corn silage and whole cotton-seed (84:16, DM basis) plus 2.2 kg alfalfa hay/d (Trial 2 only). Concentrate DM intake was 2.3 kg lower and forage DM intake 2.3 kg higher when cows were fed to production (treatments 2, 3, and 4). Milk production was highest in both trials for treatment 2. Fat test was lowest for twice daily ad libitum feeding with no differences found between other methods. Body weight change was similar across treatments and trials. Milk income was similar, fed costs higher, and income over feed cost lower for treatment 1 than for other methods in both trials. Three methods of feeding concentrate according to production were equally effective in maximizing profit.

Animal Feed↗

PubMed1989

Parturient hypocalcemia in jersey cows fed alfalfa haylage-based diets with different cation to anion ratios.

Jersey cows were fed three alfalfa haylage-based diets with different cation-anion balances beginning 6 wk preceding third or later calving and ending 24 to 36 h postpartum. Sodium and Cl as percentages of dietary DM were .08 and 1.66 in diet 1 (anionic, 5 cows), .44 and .91 in diet 2 (intermediate, 6 cows), and 1.60 and .34 in diet 3 (cationic, 6 cows). Cation-anion balances were 22, 60, and 126 meq/100 g DM; Ca:P ratios averaged 4:1. Cows fed diet 1 in comparison with cows fed diets 2 or 3 over 6 wk had similar concentrations of Ca, P, and Na but higher concentrations of Mg and K in plasma and higher urinary excretions of Ca and Mg. Concentrations of 1,25-dihydroxyvitamin D 3 d before parturition were higher in cows fed diet 1 than in cows fed diets 2 or 3. Within 36 h after calving, mean concentrations of Ca in plasma (mg/dl, range) of cows fed diets 1 to 3, respectively, were 7 (8.7 to 6.2), 6.5 (7.8 to 3.9), and 6.3 (7.8 to 3.8). Number of cases of clinical milk fever by diet were 0 of 5, 2 of 6, and 1 of 6 cows. Alteration of dietary cation-anion balance by addition of Cl may effectively reduce incidence and severity of parturient hypocalcemia.

Animal Feed↗

PubMed1988

Reuse of hemodialyzers. Results of nationwide surveillance for adverse effects.

In 1986, the Centers for Disease Control, in collaboration with the Health Care Financing Administration, surveyed 1350 chronic hemodialysis centers in the United States to ascertain practices associated with the reuse of disposable hemodialyzers and the frequency of pyrogenic reactions and septicemia among patients. Reuse of hemodialyzers was reported by 63% of the centers. Centers that used RenNew-D (n = 5) for reprocessing hemodialyzers, compared with centers that did not reuse (n = 495), were more likely to report pyrogenic reactions (60% vs 13%) and episodes of septicemia (100% vs 55%) among their patients. Reusing hemodialyzers more than 20 times and, in some instances, also using manual reprocessing systems was significantly associated with clustering of pyrogenic reactions regardless of the type of germicide used. To detect membrane leaks developing after multiple reuses, air-pressure-leak tests should be performed on all reprocessed hemodialyzers.

Disinfectants↗

PubMed1988

Phenotypic and reversion analysis of a Salmonella typhimurium constructed to have an arginine codon at the hisG46 missense codon.

Of the 6 single-base mutations that would be predicted to change the missense mutation hisG46 away from a proline codon in the Salmonella/microsome mutagen selection assay for histidine-independent revertants, only 5 have been observed. We have used site-specific mutagenesis to make the unobserved mutant [CCC (proline)----CGC (arginine)] codon in the Salmonella genome. Experiments with this arginine mutant demonstrate that, like bacteria containing the hisG46 mutation, bacteria with the arginine missense mutation are histidine auxotrophs which are capable of reversion to histidine independence. However, unlike the ATP phosphoribosyltransferase coded by the hisG46 his G gene (with a proline), the arginine mutant enzyme is partially active. This is indicated by a histidine-independent phenotype when the arginine hisG gene is present in multiple copies.

ATP Phosphoribosyltransferase↗

PubMed1988

An analysis of the mutagenicity of 1,2-dibromoethane to Escherichia coli: influence of DNA repair activities and metabolic pathways.

The mutagenicity of 1,2-dibromoethane (EDB) to Escherichia coli was reduced by the UV light-induced excision repair system but unaffected by the loss of a major apurinic/apyrimidinic site repair function. At high doses, 70-90% of the EDB-induced mutations were independent of SOS-mutagenic processing and approximately 50% were independent of glutathione conjugation. The SOS-independent mutations induced by EDB were unaffected by the enzymes that repair alkylation-induced DNA lesions. EDB-induced base substitutions were dominated by GC to AT and AT to GC transitions. These results suggest that EDB-induced premutagenic lesions have some, but not all, of the characteristics of simple alkyl lesions.

Biotransformation↗

PubMed1988

The medical evaluation of elderly patients with major depression.

Elderly patients hospitalized for management of major depression frequently have an extensive medical evaluation to determine if physical illness is masquerading as, or serving as the precipitating event for, the depression. The purpose of this study was to determine the incidence of newly discovered medical problems and the yield of various diagnostic modalities in such elderly depressed patients. Of 100 depressed geropsychiatric inpatients, the most frequent new diagnoses included: electrolyte abnormalities (6 patients), bacteriuria (13), medication reactions (7), exacerbation of previous thyroid disease (6), new thyroid function abnormalities (3), and renal failure, Parkinson's Disease, and chronic obstructive lung disease (2 each). One patient had a cerebellar hemangioblastoma, and 4 had acute illnesses. A workup including CBC, blood chemistries, urinalysis, and thyroid function tests frequently yielded abnormal results. When used as screening tests, head CT scanning, electroencephalography, and chest radiography did not affect management. We conclude that elderly depressed patients have a high prevalence of undiscovered physical illnesses, but that history, physical examination, and simple laboratory evaluation may be sufficient to guide their workups.

Acute Disease↗

PubMed1988

Eye movements on brain maps.

This report shows that eye movement artifact, either in the form of up-down or side to side movements, can be clearly demonstrated on brain maps by carefully adjusting the gain in order to delineate the distribution of activity on the anterior regions. Clearly circumscribed activity then appears above (up-down) or to the side (side-side) of each eye.

Blinking↗

PubMed1988

The effect of beta-blockers on mental performance on older hypertensive patients.

This double-blind, three-way crossover study measured the influence of beta-blocker treatment on drowsiness and mental test performance in older hypertensive patients and determined if lipophilicity was a determinant of these effects. Twenty-seven hypertensive patients (mean age, 63 +/- 3 years) were studied. Patients received two weeks each of daily treatment with placebo, 100 mg of atenolol, or 150 mg of metoprolol tartrate and were evaluated on the 14th day of each treatment period, after which their next treatment period began. Mental performance was measured using Trails-A maze testing. Drowsiness was measured subjectively using a visual analogue scale, and objectively using critical fusion-frequency threshold testing. Blood pressure control was equivalent and clinically adequate in all subjects. Steady-state levels of metoprolol tartrate (235.7 +/- 46 ng/mL) and atenolol (453.6 +/- 56 ng/nL) achieved were those expected to produce similar beta-blockade. Mental performance as measured by Trials-A testing showed better scores during beta-blocker treatment compared with placebo. Trails-A scores improved as patients went from placebo to metoprolol treatment, but did not change as patients went from placebo to atenolol treatment. Critical fusion-frequency threshold measurements were lower following administration of both drugs than following that of placebo, but subjectively there was no difference in feelings of lethargy between either beta-blocker and placebo. These data show greater improvement in mental testing performance to be associated with metoprolol treatment, but neither produced more lethargy than placebo in elderly patients.

Aged↗

PubMed1987

A controlled study of survival with dementia.

Widely conflicting data exist regarding the relationship of dementia to mortality and the relative risk of senile dementia of the Alzheimer type vs multi-infarct dementia with respect to mortality. In a historic prospective study, 202 patients with dementia were matched by age and sex with 202 nondemented controls attending the same geriatric assessment clinic and receiving comparable medical and psychiatric care. The three-year survival rate was 70% for patients with dementia and 84% for controls. Patients with multi-infarct dementia survived more poorly than patients with senile dementia of the Alzheimer type, but the difference did not reach statistical significance. The relative risk associated with dementia in the context of a multivariate analysis was 1.92 (95% confidence [1.25, 2.97]). We conclude that dementia carries a significantly increased risk of mortality but that the survival of patients with dementia may be better than previous reports would suggest.

Aged↗