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Biomedical subjects

D Fish

Publications and source records attributed to D Fish.

At least 19 recordsLinked to original sources
PubMed2000

The safety profile of the fluoroquinolones.

BACKGROUND: Premarketing trials showed the fluoroquinolone agents to have a favorable side-effect profile, with treatment-related adverse events comprising gastrointestinal, central nervous system, and dermatologic effects that were generally mild and reversible on cessation of treatment. However, postmarketing surveillance studies have identified severe adverse events, including severe anaphylaxis, QTc-interval prolongation, and potential cardiotoxicity, associated with 3 quinolone agents that either resulted in the removal of the agent from the market (temafloxacin and grepafloxacin) or significantly restricted its use due to substantial mortality and morbidity associated with liver toxicity (trovafloxacin). To date, there have been no such significant adverse events associated with the older fluoroquinolone agents, including ciprofloxacin, ofloxacin, norfloxacin, and levofloxacin. However, there are fewer data from postmarketing surveillance studies on the most recently approved agents, such as moxifloxacin and gatifloxacin, or agents awaiting approval, such as gemifloxacin. OBJECTIVE: This paper examines safety data from the premarketing trials and postmarketing surveillance studies of fluoroquinolones available in the United States. METHODS: A MEDLINE search was performed to identify all English-language studies published since 1980 concerning the safety profiles of the fluoroquinolones. CONCLUSIONS: The fluoroquinolone antibacterial agents offer broad-spectrum therapy in patients with a variety of infections. Given similar spectra of activity, the choice between quinolones may be based on differences in efficacy and safety or tolerability profiles. Most drug reactions involving these agents are minor and reversible on discontinuing treatment, but adverse effects can be associated with significant mortality and morbidity, as was seen in the case of trovafloxacin and temafloxacin.

Anti-Infective Agents↗
PubMed2000

Immunity reduces reservoir host competence of Peromyscus leucopus for Ehrlichia phagocytophila.

Infection with Ehrlichia phagocytophila in white-footed mice is transient and followed by a strong immune response. We investigated whether the presence of acquired immunity against E. phagocytophila precludes white-footed mice from further maintenance of this agent in nature. Mice were infected with E. phagocytophila via tick bite and challenged either 12 or 16 weeks later by Ixodes scapularis nymphs infected with the same agent. Xenodiagnostic larvae fed upon each mouse simultaneously with challenging nymphs and 1 week thereafter. Ticks were tested for the agent by PCR, and the prevalence of infection was compared to that in ticks that fed upon nonimmune control mice. Only 30% of immunized mice sustained cofeeding transmission of E. phagocytophila between simultaneously feeding infected and uninfected ticks, compared to 100% of control mice. An average of 6.3% of xenodiagnostic ticks acquired Ehrlichia from previously immunized mice when fed 1 week after the challenge, compared to 82.5% infection in the control group. Although an immune response to a single infection with E. phagocytophila in white-footed mice provided only partial protection against reinfection with the same agent, the majority of mice were rendered reservoir incompetent for at least 12 to 16 weeks. Immunity acquired by mice during I. scapularis nymphal activity in early summer may exclude a large proportion of the mouse population from maintaining E. phagocytophila during the period of larval activity later in the season.

Animals↗
PubMed2000

Acquisition of coinfection and simultaneous transmission of Borrelia burgdorferi and Ehrlichia phagocytophila by Ixodes scapularis ticks.

The agents of Lyme disease (Borrelia burgdorferi) and human granulocytic ehrlichiosis (Ehrlichia phagocytophila) are both transmitted by the tick Ixodes scapularis. In nature, ticks are often infected with both agents simultaneously. We studied whether previous infection with either Borrelia or Ehrlichia in ticks would affect acquisition and transmission of a second pathogen. Ehrlichia-infected I. scapularis nymphs were fed upon Borrelia-infected mice, and Borrelia-infected I. scapularis nymphs were fed upon Ehrlichia-infected mice. The efficiency with which previously infected nymphal ticks acquired a second pathogen from infected hosts was compared to that of uninfected ticks. An average of 51% +/- 15% of ticks acquired Ehrlichia from infected mice regardless of their prior infection status with Borrelia. An average of 85% +/- 10% of ticks acquired Borrelia from infected mice regardless of their prior infection status with Ehrlichia. Also, we assessed the efficiency with which individual nymphs could transmit either agent alone, or both agents simultaneously, to individual susceptible hosts. An average of 76% +/- 9% of Borrelia-infected ticks and 84% +/- 10% of Ehrlichia-infected ticks transmitted these agents to mice regardless of the presence of the other pathogen. There was no evidence of interaction between the agents of Lyme disease and human granulocytic ehrlichiosis in I. scapularis ticks. The presence of either agent in the ticks did not affect acquisition of the other agent from an infected host. Transmission of the agents of Lyme disease and human granulocytic ehrlichiosis by individual ticks was equally efficient and independent. Dually infected ticks transmitted each pathogen to susceptible hosts as efficiently as ticks infected with only one pathogen.

Animals↗
PubMed2000

Attachment of Borrelia burgdorferi within Ixodes scapularis mediated by outer surface protein A.

Borrelia burgdorferi outer surface protein (Osp) A has been used as a Lyme disease vaccine that blocks transmission: OspA antibodies of immune hosts enter ticks during blood feeding and destroy spirochetes before transmission to the host can occur. B. burgdorferi produce OspA in the gut of unfed Ixodes scapularis ticks, and many spirochetes repress OspA production during the feeding process. This preferential expression suggests that OspA may have an important function in the vector. Here we show that OspA mediates spirochete attachment to the tick gut by binding to an I. scapularis protein. The binding domains reside in the central region and COOH-terminus of OspA. OspA also binds to itself, suggesting that spirochete-spirochete interactions may further facilitate adherence in the gut. OspA-mediated attachment in the tick provides a possible mechanism for how stage-specific protein expression can contribute to pathogenesis during the B. burgdorferi natural cycle.

Amino Acid Sequence↗
PubMed2000

Effects of grain processing and bovine somatotropin on metabolism and ovarian activity of dairy cows during early lactation.

This study compared the effects of exogenous bovine somatotropin (bST) on the metabolism and ovarian activity of cows fed diets differing in ruminally degradable starch. Twenty-four multiparous and eight primiparous Holstein cows in early lactation were divided into four groups and fed diets containing 39% grain as steam-flaked sorghum or steam-rolled corn with or without bST for 90 d in a 2 x 2 factorial design. Flaked sorghum improved energy status of cows during early lactation, tending to increase plasma glucose and insulin. Administration of bST decreased plasma urea nitrogen and increased nonesterified fatty acids (NEFA). Plasma levels of beta-hydroxybutyrate (BHBA) and hepatic concentrations of triglycerides were not altered by treatments. Temporal changes in plasma glucose, urea nitrogen, NEFA, and BHBA were detected in a quadratic manner and insulin increased linearly with time, but treatments did not affect postpartum changes in these metabolites. There were greater decreases in body weight and net energy balance in cows on bST during the first 7 wk of treatment. Cows receiving bST took longer to reach the nadir of negative energy balance, and bST tended to delay the period to reach a positive energy balance. Follicular populations and incidence of cystic ovaries were not affected by treatments, but cows receiving bST had fewer double ovulations. Flaked sorghum increased plasma progesterone during the early luteal phase of the first two postpartum estrous cycles. Feeding more ruminally degradable starch improved the energy status and luteal activity of cows in early lactation.

3-Hydroxybutyric Acid↗
PubMed2000

Sporadic fatal insomnia: a case study.

A 58-year-old man died after a 27-month illness characterized by insomnia, confirmed by polysomnography. He was homozygous for methionine at codon 129 of the prion gene but had no mutation in the prion gene. Neuropathology showed thalamic and olivary atrophy and no spongiform changes. Paraffin-embedded tissue blotting demonstrated abnormal prion protein in the brain. This is the first case of the sporadic form of fatal familial insomnia with demonstration of the disorder by polysomnography.

Humans↗
PubMed1999

Temporal relation between Ixodes scapularis abundance and risk for Lyme disease associated with erythema migrans.

Understanding the role that nymphal and female ticks, Ixodes scapularis, have in the epidemiology of Lyme disease is essential to the development of successful prevention programs. In this study, the authors sought to evaluate the seasonal and annual relations between tick densities and patients > or = 16 years of age diagnosed with erythema migrans (EM), the rash associated with early Lyme disease. Ticks were collected weekly by drag sampling throughout most of the year from 1991 to 1996 in Westchester County, New York. The number of EM cases was based on patients diagnosed at the Westchester County Medical Center using Centers for Disease Control and Prevention (CDC) criteria. No patients with EM were diagnosed from January through April, when only adult ticks were active. Correlation analysis between monthly tick densities and EM incidence was significant for nymphs (r = 0.87, p < 0.01), but not for adult ticks (r = -0.57, p > 0.05). There was a strong, although not significant, correlation between peak annual number of patients with EM and peak nymphal tick abundance (r = 0.76, p = 0.08). These data indicate that bites from adult I. scapularis only rarely result in Lyme disease, and that annual nymphal tick abundance determines exposure. This suggests that annual fluctuations in Lyme disease case numbers are largely due to natural changes in tick abundance and, therefore, that control of nymphal I. scapularis should be a major component of Lyme disease prevention efforts.

Adult↗
PubMed1999

Treatment of photosensitive epilepsy using coloured glasses.

A recently introduced optometric technique, colorimetry, enables the perceptual effects of ophthalmic tints to be evaluated subjectively, optimized, and then prescribed in tinted spectacles. The new technique is beneficial in reducing visual stress in patients with dyslexia and migraine. We describe an open trial designed to ascertain: (1) whether the colorimetry assessment, as it is now given, is safe for the investigation of photosensitive patients in optometry clinics where colorimetry equipment is most readily available, but where EEG control is not practical; (2) what proportion of patients with photosensitive epilepsy is likely to benefit to the extent already described in individual cases; (3) whether a tint selected by colorimetry could be shown to reduce the incidence of paroxysmal epileptiform EEG activity in response to flicker and patterns, thereby validating the subjective methods and corroborating the reported seizure reduction. Twenty-four females and nine males (aged 12-43 years) took part. All the patients had suffered visually-provoked seizures, had exhibited a photoparoxysmal response on at least one previous EEG recording, and had received a diagnosis of photosensitive epilepsy. Twenty-two were currently experiencing seizures. A further EEG was recorded in all except seven cases: a routine resting record, followed by hyperventilation. Colorimetry was performed after hyperventilation and before photic stimulation. Twenty-three (70%) reported beneficial effects during colorimetry and were prescribed glasses. There was a preponderance of lenses with a rose or purple colour, in contrast to patients with dyslexia. Seventeen of the 23 patients were available at follow-up, an average of 2.4 years later. Thirteen (57%) reported benefits, and said they were still using the lenses. In six of the 13 the benefits were pronounced, including a reduction of dizziness from fluorescent lighting, elimination of aura when using computer screens etc. Only in three cases was there a reduction in seizures that could reasonably be attributed to the use of lenses; in two of these cases no medications were prescribed, and in the third the medications remained unchanged for four years, two before and two after the introduction of the glasses. In an additional four cases a reduction in seizures was observed but medication had been changed. There was a modest reduction in EEG photosensitivity with the coloured lenses but also to an equivalent or lesser extent with grey in all of the eight patients examined in this way. One patient had seizures during colorimetry, but the seizures were not accompanied by scalp EEG changes.

Adolescent↗
PubMed1999

Comparative vector competence of Dermacentor variabilis and Ixodes scapularis (Acari: Ixodidae) for the agent of human granulocytic ehrlichiosis.

Vector competence of Ixodes scapularis Say and Dermacentor variabilis Say for the agent of human granulocytic ehrlichiosis (HGE) was compared. Five white-footed mice, Peromyscus leucopus Rafinesque, were inoculated intra-peritoneally with blood from a mouse infected with the agent of HGE. Approximately 100 I. scapularis and D. variabilis larvae were placed on each mouse and allowed to feed to repletion. Fed larvae were collected, separated according to species and allowed to molt to nymphs. Twenty-six per cent of I. scapularis (34/131) and 11% of D. variabilis (11/96) tested positive for the agent of HGE by polymerase chain reaction (PCR) after molting to nymphs. Positive I. scapularis nymphs transmitted the agent of HGE to P. leucopus mice in 5 of 5 trials. In contrast, the positive D. variabilis nymphs did not transmit the agent of agent of HGE in any of 6 trials. In a 2nd experiment, 3 P. leucopus mice were infested with I. scapularis nymphs that were infected with the agent of HGE. All 3 mice became infected with the agent of HGE and approximately 300 D. variabilis larvae were placed on each mouse and allowed to feed to repletion. Larvae were collected and allowed to molt to nymphs as before. Approximately 8% (5/60) of the nymphs became positive for the agent of HGE as determined by PCR. Twenty-five of these nymphs were then placed on each of 9 P. leucopus mice and allowed to feed to repletion. Evidence of transmission was not observed in any of 9 mice exposed to D. variabilis nymphs. These results demonstrate that although I. scapularis is a competent vector of the agent of the HGF, D. variabilis is not.

Anaplasmataceae↗
PubMed1998

Estimation of the incidence of Lyme disease.

The incidence of Lyme disease in most endemic areas is unknown but will be an important factor in determining the cost-effectiveness of Lyme disease vaccines in those areas. The authors developed a deterministic model with nine components to estimate the frequency of Ixodes scapularis tick bites and the resulting incidence of Lyme disease in residents of endemic areas. For each component, best point estimates and plausible ranges of values were based on the published literature, unpublished data, expert opinion, or a combination of the above. By using the mean, crude, annual total of 3,827 Lyme disease cases reported from the endemic county of Westchester, New York, in 1991-1994, a mean of 178,889 I. scapularis bites (20.4 per 100 person-years) and a mean of 10,632 incident Lyme disease cases (1.2 per 100 person-years) were estimated to have occurred per year. Results of a sensitivity analysis that used two different methods suggested that this deterministic model is reasonably robust. In conclusion, according to this model, the incidence of Lyme disease in Westchester County is several-fold higher than suggested by the current passive reporting system.

Animals↗
PubMed1998

Induction of hepatic cytochrome P-450 by phenobarbital in semi-aquatic frog (Rana pipiens).

Hepatic microsomal cytochrome P450 (equivalent to rat P4502B1 isozymic form, a CYPIIB gene product) can be induced by pentobarbital (PB) in the adults of the semiaquatic frog, Rana pipiens (as in other terrestrial vertebrates), but not in adults of the aquatic frog Xenopus laevis or in bluegill sunfish (Lepomis macrochirus). The activity of PB-induced P450 (2B1) towards aldrin and pentoxyresorufin increases respectively by about 2- and 10-fold. This enzyme is not inducible during larval and postlarval stages of R. pipiens. However, cytochrome P4501A1 (CYPIA1 gene product) is inducible by beta-naphthoflavone in all these species. Both CYPIA and CYPIIB genes are expressed, as determined by the catalysis of their protein products, during larval, postlarval, and adult stages of R. pipiens. The concentration of P450 increases slightly during the postlarval stages until the adult stage, ready to migrate to land, is reached. This increase seems to be mostly due to 2B1-type cytochrome P450 as judged by a large increase in aldrin epoxidase but not of 7-ethoxyresorufin O-deethylase activity. It is hypothesized that the evolution of true terrestrialness, and not the evolution of air-breathing lungs alone, is required for the transcriptional activation of CYPIIB gene by PB.

Age Factors↗
PubMed1998

Granulocytic ehrlichiosis in the laboratory mouse.

C3H mice that were inoculated with ehrlichiae isolated from a patient with human granulocytic ehrlichiosis (HGE) developed anemia and leukopenia, but by day 24, they returned to normal values. Granulocytic morulae were present in peripheral blood and spleen smears on days 5 and 10, and there was a reduction in morulae on day 17. Ehrlichiae were present in HL-60 cell cultures of blood and spleen from all mice at all intervals. Pathogenicity, but not infectivity, waned with mouse passage but could be resurrected by SCID mouse passage. Various methods were tested for their relative sensitivity in detecting infection: blood smears, HL-60 cell cultures, polymerase chain reaction (PCR) amplification of a 16S recombinant DNA target, and a mouse infectivity assay. All assays detected the HGE agent in blood during early infection, but PCR and the mouse infectivity assay were most sensitive during late infection. Xenodiagnosis demonstrated that mice remain persistently infected through 55 days.

Age Factors↗
PubMed1998

Acquisition and transmission of the agent of human granulocytic ehrlichiosis by Ixodes scapularis ticks.

The purpose of the present study was to investigate the transmission of a human isolate of the agent of human granulocytic ehrlichiosis (HGE agent) from infected mice to larval ticks and to examine the population kinetics of the HGE agent in different stages of the tick life cycle. The HGE agent was quantitated by competitive PCR with blood from infected mice and with Ixodes scapularis ticks. The median infectious dose for C3H mice was 10(4) to 10(5) organisms when blood from an infected severe combined immunodeficient mouse was used as an inoculum. Uninfected larval ticks began to acquire infection from infected mice within 24 h of attachment, and the number of HGE agent organisms increased in larval ticks during feeding and after detachment of replete ticks. Molted nymphal ticks, infected as larvae, transmitted infection to mice between 40 and 48 h of attachment. Onset of feeding stimulated replication of the HGE agent within nymphal ticks. These studies suggest that replication of the HGE agent during and after feeding in larvae and during feeding in nymphs is a means by which the HGE agent overcomes inefficiencies in acquisition of infection by ticks and in tick-borne transmission to mammalian hosts.

Animals↗
PubMed1998

African swine fever virus infection in the argasid host, Ornithodoros porcinus porcinus.

The pathogenesis of African swine fever virus (ASFV) infection in Ornithodoros porcinus porcinus was examined in nymphal ticks infected with the ASFV isolate Chiredzi/83/1. At times postinfection (p.i.) ranging from 6 h to 290 days, ticks or dissected tick tissues were titrated for virus and examined ultrastructurally for evidence of virus replication. The ASFV infection rate in ticks was 100% in these experiments, and virus infection was not associated with a significant increase in tick mortality. Initial ASFV replication occurred in phagocytic digestive cells of the midgut epithelium. Subsequent infection and replication of ASFV in undifferentiated midgut cells was observed at 15 days p.i. Generalization of virus infection from midgut to other tick tissues required 2 to 3 weeks and most likely involved virus movement across the basal lamina of the midgut into the hemocoel. Secondary sites of virus replication included hemocytes (type I and II), connective tissue, coxal gland, salivary gland, and reproductive tissue. Virus replication was not observed in the nervous tissue of the synganglion, Malpighian tubules, and muscle. Persistent infection, characterized by active virus replication, was observed for all involved tick tissues. After 91 days p.i., viral titers in salivary gland and reproductive tissue were consistently the highest detected. Successful tick-to-pig transmission of ASFV at 48 days p.i. correlated with high viral titers in salivary and coxal gland tissue and their secretions. A similar pattern of virus infection and persistence in O. porcinus porcinus was observed for three additional ASFV tick isolates in their associated ticks.

African Swine Fever Virus↗
PubMed1998

Prevention of Borrelia burgdorferi transmission in guinea pigs by tick immunity.

We examined the effect of repeated infestation of guinea pigs with Ixodes scapularis on the capacity of ticks to transmit Borrelia burgdorferi infection. Repeated challenges with nymphs or larvae lead to a reduction in duration of nymphal tick attachment and weight of recovered ticks consistent with the development of tick immunity. Only one of 18 I. scapularis-immune guinea pigs challenged with B. burgdorferi-infected nymphal ticks became infected, whereas 10 of 18 naive guinea pigs similarly challenged became infected. We conclude that tick immunity interferes with borrelial transmission.

Animals↗