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Biomedical subjects

J A Elliott

Publications and source records attributed to J A Elliott.

At least 55 records · Page 3Linked to original sources
PubMed1993

Identification of Leuconostoc spp. by analysis of soluble whole-cell protein patterns.

Leuconostoc spp. share several physiologic characteristics, which sometimes makes it difficult to identify these organisms to the species level. We developed a system, based on the patterns of soluble whole-cell proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, that was able to discriminate between the six Leuconostoc spp. that are capable of growth at 37 degrees C. Nine unidentified Leuconostoc-like bacterial isolates that were included in the study did not fit any of the protein profiles of the type strains and may represent new Leuconostoc spp.

Bacterial Proteins↗
PubMed1992

Identification of an epidemic strain of Acinetobacter baumannii using electrophoretic typing methods.

Nosocomial infections due to Acinetobacter baumannii dramatically increased in a Lebanese medical center following an outbreak of hostilities in Lebanon in 1984. The incidence of infection caused by this organism has remained high in this institution, thus requiring the implementation of a strain typing system to aid in infection control. Three methods were investigated for their utility in differentiating among a representative group of 36 nosocomial Acinetobacter baumannii isolates obtained over a 10 month period from specimens of hospitalized patients. Isolates were typed by antibiogram analyses, plasmid fingerprinting, and total cell protein profiles. Only three distinct total cell protein profiles were detected, with one pattern accounting for 26 (72.2%) of the isolates. However, eight different plasmid profiles were observed, with 20 (55.5%) isolates having the same profile. Eleven distinct antibiograms were seen with the most prevalent pattern occurring in 21 isolates. Twenty of the 21 (95%) isolates with the common antibiogram also had the same plasmid profile and total protein profile (44.4% of total isolates). The combination of these three typing methods was useful in tracing the spread of these organisms in the medical center. The data obtained suggest the distribution of a common strain among at least six wards of this hospital.

Acinetobacter↗
PubMed1992

Clusters of invasive group A streptococcal infections in family, hospital, and nursing home settings.

The spread of group A streptococcal infection to close contacts of infected persons is well recognized. With the resurgence of invasive group A streptococcal infections, there is an increased potential for clusters of patients with invasive disease. We reviewed data collected since December 1988 at the Centers for Disease Control (Atlanta) to identify clusters of infection in which one or more patients had invasive disease. Twelve family clusters were identified. Infection in index cases included the toxic shock-like syndrome and septicemia. Infection in family contacts included invasive infections, pharyngitis, or asymptomatic carriage. Most invasive disease occurred in adults, while the majority of noninvasive infections were in children. Five nosocomial clusters with spread of infection from patients to hospital personnel were documented. All index patients had the toxic shock-like syndrome; secondary infections included the toxic shock-like syndrome, pneumonia, bullous cellulitis, lymphangitis, and pharyngitis. Clusters of invasive infections also were identified in five nursing homes. Pneumonia, cutaneous infections, and the toxic shock-like syndrome occurred most commonly. Clustering by nursing home unit occurred in three outbreaks. In hospitals and nursing homes, improved infection control will likely decrease secondary spread; in families, spread of disease may be prevented by identifying and treating those harboring the organism or by chemoprophylaxis. Studies that characterize the rate of secondary infection are needed before definitive recommendations can be made.

Adult↗
PubMed1992

Melatonin: a major regulator of the circadian rhythm of core temperature in humans.

The circadian rhythm of core body temperature (BTc), with maxima during the day and minima at night, is normally coupled with the sleep-wake cycle. Pineal melatonin secretion occurs contemporaneously during the nighttime hours and is mediated by the activation of beta-adrenergic receptors during darkness. The hypothesis that nocturnal melatonin secretion may be involved in the regulation of the human circadian BTc rhythm was examined. The temporal relationship between melatonin and the circadian BTc rhythm was characterized in 12 young women, normally entrained to the light-dark cycle. Melatonin levels were manipulated through the administration of exogenous melatonin (2.5 mg, orally) during the daytime (n = 6) or suppression of endogenous nocturnal melatonin secretion by the beta-adrenergic antagonist atenolol (100 mg; n = 6) in double blind placebo-controlled experiments conducted during 2 consecutive days. Serum melatonin levels and BTc were monitored at 20- and 10-min intervals, respectively. In a nightshift worker the temporal relationship between the circadian rhythm of melatonin and BTc was investigated before and after entrainment to a reversed wake-sleep cycle. Our data show that in normally entrained subjects, the time course and amplitude of nocturnal melatonin secretion were temporally coupled with the decline of BTc (r = 0.97; P less than 0.00001). The same occurred in the nightshift worker, both during the dissociation and after entrainment to the reversed sleep-wake cycle. Compared with placebo, administration of melatonin significantly reduced daytime BTc (P less than 0.01), and the suppression of melatonin (by atenolol) attenuated the nocturnal decline of BTc (P less than 0.01). Cosinor analysis showed that the amplitude of the circadian BTc rhythm was reduced by about 40% in response to both daytime melatonin administration (P less than 0.05) and nocturnal melatonin suppression (P less than 0.02). In conclusion, circadian rhythms of melatonin and BTc are inversely coupled. The demonstrated hypothermic properties of melatonin are accountable for the generation of at least 40% of the amplitude of the circadian BTc rhythm. Manipulation of melatonin levels might be clinically useful to resynchronize the BTc rhythm under conditions of BTc rhythm desynchronization.

Adult↗
PubMed1991

Differentiation of Lactococcus lactis and Lactococcus garvieae from humans by comparison of whole-cell protein patterns.

We tested 12 reference and 24 clinical strains of lactococci for physiologic characteristics using a conventional test system, the Gen-Probe Enterococcus 2 chemiluminescence assay (Gen-Probe Inc., San Diego, Calif.), the Rapid Strep identification system (Analytab Products, Plainview, N.Y.), and whole-cell protein analysis. The Gen-Probe Enterococcus 2 chemiluminescence assay for Enterococcus identification was negative with all strains. Neither the conventional test nor the Rapid Strep identification system could differentiate between the two Lactococcus spp. most commonly isolated from humans. A simple procedure, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was developed for comparing the whole-cell protein patterns of Lactococcus spp. L. lactis and L. garvieae were differentiated by unique protein patterns.

Bacterial Proteins↗
PubMed1991

Amplification of pulsatile LH secretion by exogenous melatonin in women.

The effect of melatonin on pulsatile LH secretion was investigated in early follicular phase women (days 2-5). During two consecutive days, at 0800 hrs., subjects received placebo or oral melatonin in a random double-blind fashion. Two doses of melatonin were used; 100 mg single dose (N = 6) or 2.5 mg in three divided doses (N = 5), (1 mg at 0800 hrs., 0.75 mg at 1000 and 1200 hrs.). Blood samples were collected every 10 minutes, between 0900-1700 hrs. Compared with placebo, melatonin administration augmented LH pulse amplitude (p less than 0.01) without changing LH pulse frequency. The integrated LH secretion was significantly increased (p less than 0.01) after melatonin, independent of doses administered. Serum FSH and ovarian steroids were not altered. It is concluded that exogenous melatonin enhances LH pulse amplitude in women, without modifying FSH and ovarian steroid levels.

Adult↗
PubMed1990

Streptococcus mitis sepsis in bone marrow transplant patients receiving oral antimicrobial prophylaxis.

PURPOSE: Streptococcal infection has increasingly become a problem in neutropenic patients. We report on an outbreak of Streptococcus mitis sepsis in six bone marrow transplant patients receiving oral antimicrobial prophylaxis. PATIENTS AND METHODS: We performed an epidemiologic study of all patients in our bone marrow transplant program from 1986 to 1988. The hospital and microbiology records for all patients were reviewed. All bone marrow patients were treated according to specified protocols, including an oral prophylactic antimicrobial regimen that was changed in late 1987 from vancomycin/polymyxin/tobramycin to norfloxacin. Identification, susceptibility testing, and whole cell protein analysis of streptococcal isolates were performed at the Reference and Antimicrobial Investigations Laboratories at the Centers for Disease Control. RESULTS: We detected six cases of S. mitis sepsis among 21 patients undergoing bone marrow transplantation. No other concurrent pathogen was isolated from any patient at the time of the S. mitis bacteremia. Bacteremia developed within 72 hours of transplant in five of six patients and was associated with severe mucositis in four patients. An environmental study failed to reveal any common source for the outbreak, and whole cell protein analysis of all six S. mitis isolates revealed each to be distinct. Of 12 patients receiving oral vancomycin/polymyxin/tobramycin, one developed S. mitis bacteremia, versus five of nine patients receiving norfloxacin (p less than 0.03). CONCLUSION: We believe S. mitis bacteremia is a potential complication of bone marrow transplantation and is associated with antimicrobial prophylaxis with norfloxacin, especially in the setting of mucositis.

Administration, Oral↗
PubMed1990

Whole-cell protein patterns of nonhemolytic group B, type Ib, streptococci isolated from humans, mice, cattle, frogs, and fish.

Whole-cell protein and physiological patterns of nonhemolytic group B, type Ib, streptococci isolated from humans, cattle, frogs, fish, and mice were compared. Isolates from humans, fish, and mice were identical. Only minor differences were seen in the isolates from human, bovine, and frog sources. Nonhemolytic group B streptococci from humans, fish, and mice and, to a lesser extent, from cattle and frogs share several characteristics, including a high similarity in proteins (on the basis of molecular weight); this suggests that they may have a common ancestry.

Animals↗
PubMed1990

Major subtypes of invasive Haemophilus influenzae from 1983 to 1985 in Atlanta, Ga.

We compared outer membrane protein (OMP) patterns of Haemophilus influenzae isolated in metropolitan Atlanta, Ga., from July 1983 to June 1985. Of 74 randomly selected H. influenzae serotype b, biotype I, isolates (24% of the total number of H. influenzae, and 32% of the total number of H. influenzae serotype b, biotype I, isolates), 66 (89.2%) had the same OMP pattern. Of the remaining eight, five (6.7%) had an identical OMP pattern. The other three isolates had separate and distinct patterns. A greater diversity of OMP patterns was found with H. influenzae serotype b, biotype II, and nonserotypeable H. influenzae. Of the 18 H. influenzae serotype b, biotype II, isolates (5.8% of the total number of H. influenzae isolates), 1 had an OMP pattern similar to that of the predominate biotype I OMP type, 6 (33% of the biotype II) had the same pattern, and 11 had heterogeneous patterns. Of the 19 recoverable, nonserotypeable biotype II isolates (6.8% of the total number of H. influenzae), 18 had different OMP patterns, and no pattern was similar to those observed with serotype b. These findings indicate that most H. influenzae strains isolated during this 2-year period were indistinguishable by serotype, biotype, or OMP patterns.

Bacterial Outer Membrane Proteins↗
PubMed1989

Reception of photoperiodic information by fetal Siberian hamsters: role of the mother's pineal gland.

The rate of reproductive development in juvenile male Siberian hamsters is strongly influenced by daylength (photoperiod). Recent studies indicate that reception of photoperiodic cues begins during fetal life. The present experiments yielded a further demonstration that developing male Siberian hamsters receive information about the photoperiod to which their mother is exposed during pregnancy. The possibility that photoperiodic information is transmitted from mother to young after birth was investigated by cross-fostering young gestated on 12L and 16L to mothers from the other photoperiod. Litters were cross-fostered on the day of birth and then were transferred, along with their foster mothers, to 14L. We found no influence of the mother after birth, indicating that transmission of photoperiodic information from mother to young must occur during gestation. To determine if the pineal gland of the mother is required for this response, adult females were pinealectomized or sham-operated and paired with intact males in 12L, 14L, or 16L. After parturition parents and offspring were exposed to 14L. The influence of prenatal photoperiod on postnatal testicular development in 14L was blocked by pinealectomy of the mother. Postnatal testicular development was retarded in offspring that experienced a photoperiod transfer from either 15L to 14L or 8L to 12L at birth. In contrast, the inhibitory effect of a transfer from 16L to 14L at birth was abolished when juvenile males were exposed to a single long photoperiod (16.3 h light) at age 17-21 days and then were returned to 14L.

Animals↗
PubMed1989

Control of torpor and body weight patterns by a seasonal timer in Siberian hamsters.

Two experiments were designed to assess whether the short-day-induced patterns of shallow daily torpor, body weight, and other seasonal responses (food intake and pelage pigmentation) exhibited by Siberian hamsters (Phodopus sungorus sungorus) are under the control of a "seasonal timekeeping mechanism" that is independent of reproductive status [testosterone, (T)]. We examined whether the patterning and expression of these seasonal responses were altered by decreases in serum T that accompany gonadal regression during the first 8 wk of short-day exposure (i.e., the "preparatory phase" of the torpor season) or by experimental increases in serum T after this phase. Short-day-housed, castrated hamsters bearing T implants had long-day levels of the hormone and did not exhibit torpor. Appropriate seasonal patterns and levels of torpor, body weight, pelage color stage, and food intake were exhibited after T implant removal although serum T was clamped to long-day levels during the preparatory phase. In animals that were gonad intact during the preparatory phase and were subsequently castrated and given T implants, torpor did not occur as long as the implants were in place. However, the patterns and levels of daily torpor, food intake, and body weight rapidly returned to appropriate seasonal values compared with the castrated, blank-implanted controls on T implant removal; these effects occurred whether the T implants were removed when torpor frequency was increasing, at its peak, or decreasing across the torpor season. T did not affect pelage color stage under any condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Effect of melatonin infusion duration and frequency on gonad, lipid, and body mass in pinealectomized male Siberian hamsters.

The goal of this study was to discriminate between two hypotheses regarding how the circadian rhythm of pineal melatonin (MEL) production transmits photoperiodic information: (1) A circadian rhythm of sensitivity to MEL regulates the hormone's effect; (2) the duration of the MEL signal, rather than its circadian timing, is the critical parameter of the MEL rhythm. The experiment examined the response of pinealectomized (PINX) male Siberian hamsters to 10-hr (short-day-type) versus 6-hr (long-day-type) duration MEL infusions (10 ng/infusion) in cycles with period lengths (T) of 18, 24, 36, and 48 hr. After cannula implantation, animals were moved from LD 16:8 to LD 10:14 (lights-on from 0500 to 1500 hr, EST), where the timed infusions began. Additional T 24 cycles included as controls employed 18-hr MEL, 18-hr saline (SAL), and 10-hr SAL infusions: Body weight and food intake were measured weekly. After 6 weeks, animals were killed; blood samples were taken for radioimmunoassay (RIA) of serum follicle-stimulating hormone (FSH) and prolactin (PRL); and terminal body, epididymal white adipose tissue (EPIWAT), and paired testis weights were recorded. Six-hour MEL infusions failed to induce short-day-type effects, regardless of the period (T) of the infusion cycle. In contrast, compared to SAL and 6-hr MEL infusions, 10-hr MEL resulted in decreases in body, EPIWAT, and testis weights in T 24, but not in T 36 or T 48. In T 18, testis, body, and EPIWAT mass were decreased, but not to the same extent as in T 24. Similarly, daily 18-hr MEL infusions (T24) were less effective as a short-day stimulus than were 10-hr MEL infusions. The effectiveness of 10-hr, but not 6-hr, MEL infusions in T 18 and T 24 is consistent with the duration hypothesis and argues against the circadian hypothesis. Neither hypothesis could have predicted that all infusion cycles of T greater than or equal to 36 hr, regardless of the infusion durations, would fail to elicit short-day-type responses. This outcome suggests a need for relatively frequent (T less than 36 hr) MEL stimulation in addition to the requirement for adequate duration of each MEL infusion.

Adipose Tissue↗
PubMed1989

Interaction of bisantrene anti-cancer agents with DNA: footprinting, structural requirements for DNA unwinding, kinetics and mechanism of binding and correlation of structural and kinetic parameters with anti-cancer activity.

A topoisomerase I assay in conjunction with covalently closed circular DNA afforded unwinding angles for a series of eight analogs of the anti-cancer agent bisantrene. Values ranging from 33 degrees to zero comprised three classes wherein the extent of DNA interaction correlates with anti-cancer activity. The binding of bisantrene compounds to T4 DNA suggests at least partial interaction via the minor groove. MPE footprinting evaluation of bisantrene showed no evidence for selective protection of a Hind III-EcoRI fragment of pBR322 suggesting a sequence neutral binding mode. Stopped flow spectrophotometry studies indicate an association rate constant for bisantrene with DNA of greater than 1 x 10(7) M-1 S-1 at 20 degrees at ionic strength of 0.1 and is considerably slower than ethidium or propidium at all ionic strengths. At least two exponential components are required to match the kinetic curves indicating a biphasic mechanism and estimates of k1 and k2 were obtained for seven drugs. The ionic strength dependence of the surfactant driven dissociation of bisantrene is in accord with a competitive mechanism for intercalation of the drugs at alternative sites. The residence time and t1/2 (app) for bisantrene are slightly larger for poly d(G.C)2 than poly d(A.T)2 and calf thymus DNA is at an intermediate value. Considerations of structural factors in the drug dissociation kinetics permit a correlation with observed anti-cancer properties of these bisantrene analogs.

Animals↗
PubMed1988

Hydroxychloroquine in steroid dependent asthma.

A recent case report suggested that hydroxychloroquine had a steroid sparing effect in a patient with severe chronic asthma. We have studied the effect of hydroxychloroquine in a group of nine steroid dependent adult asthmatic patients using a randomised double blind crossover comparison of hydroxychloroquine and placebo. Each patient received hydroxychloroquine (400 mg/day) or placebo for 2 month periods. The effect of hydroxychloroquine or placebo on asthma control was assessed by change in steroid dosage, visual analogue symptom scores, response to beta 2 agonist and peak expiratory flow rate (PFR) measurement. The dose of prednisolone required during hydroxychloroquine treatment did not differ from that during placebo treatment or in pre-trial period. There was no significant change in symptom scores of PFR measurement. In this study an 8 week treatment with hydroxychloroquine was of no benefit to patients with chronic steroid dependent asthma.

Adult↗