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Biomedical subjects

J P Davis

Publications and source records attributed to J P Davis.

At least 19 recordsLinked to original sources
PubMed2003

Effects of KHEYLRFamide and KNEFIRFamide on cyclic adenosine monophosphate levels in Ascaris suum somatic muscle.

KHEYLRF-NH(2) (AF2) is a FMRFamide-related peptide (FaRP) present in parasitic and free-living nematodes. At concentrations as low as 10 pM, AF2 induces a biphasic tension response, consisting of a transient relaxation followed by profound excitation, in neuromuscular strips prepared from Ascaris suum. In the present study, the effects of AF2 on cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP) and inositol-1,4,5-triphosphate (IP(3)) levels were measured following muscle tension recordings from 2 cm neuromuscular strips prepared from adult A. suum. AF2 induced a concentration- and time-dependent increase in cAMP, beginning at 1 nM; cAMP levels increased by 84-fold following 1 h exposure to 1 microM AF2. cGMP and IP(3) levels were unaffected by AF2 at concentrations </=1 microM. AF2-induced stimulation of cAMP was unaffected by removal of the dorsal or ventral nerve cord, even though this form of denervation abolished the excitatory phase of the tension response. The effects of 0.1 and 1 microM AF2 on cAMP were also unaffected by 10 microM SDPNFLRF-NH(2) (PF1, an inhibitory FaRP) and 10 microM PF1022A (an inhibitory cyclodepsipeptide), even though each of these peptides abolished the excitatory phase of the tension response induced by AF2. Within an alanine-scan series of AF2 analogues, only KHAYLRF-NH(2) stimulated cAMP production with equipotency to AF2; the effects of this peptide on muscle tension also mimicked AF2. Another excitatory FaRP present in nematodes, KNEFIRF-NH(2) (AF1), also stimulated cAMP production, but was 100-fold less potent than AF2. The stimulatory effects of AF1 on tension and cAMP levels were blocked by an alanine-substituted analogue of this peptide (Ala(6)-AF1, KNEFIAF-NH(2)), while the stimulatory effects of AF2 on tension and cAMP were not affected by this analogue. AF2 and AF1 increase A. suum somatic muscle cAMP by targeting different receptors. Increases in cAMP stimulated by AF2 can be decoupled from the excitatory response caused by this peptide, and it is not possible to establish a causal linkage between the contractile response elicited by this peptide and its effects on cAMP accumulation.

Animals↗
PubMed2003

Laser Doppler flux-metry in laryngeal squamous cell carcinoma.

Tumour angiogenesis has recently attracted a great deal of attention as a critical part of oncogenesis and a necessary prerequisite for a malignant phenotype. Novel antiangiogenic therapy for solid tumours including laryngeal cancer is entering clinical trials. Quantifying microvessel density is considered the gold standard for measuring baseline angiogenesis and indeed 'the response to intervention'. We hypothesize that laser Doppler flux-metry could provide a non-invasive reliable method of quantifying blood flux within tumours. The aims were to determine whether a laser Doppler flux meter could be used as a reliable and reproducible method of estimating blood flux in the human larynx and to establish baseline Doppler flux recordings for the human larynx. The method used was a validation study in patients with laryngeal squamous cell cancer and normal controls. Statistical analysis was performed using SPSS software. We have demonstrated good reproducibility of laser Doppler measurements in human laryngeal mucosa (correlation coefficient 0.956 @P = 0.01). We have also derived arbitrary means of laser Doppler flux-metry in normal laryngeal mucosa and in squamous cell carcinoma of the larynx. Comparisons between normal and tumour laser Doppler flux-metry (LDF) readings showed no significant difference. We suggest that Laser Doppler flux-metry is a potentially useful tool with which to study blood flow in the larynx and propose arbitrary LDF levels for the normal and diseased human larynx.

Carcinoma, Squamous Cell↗
PubMed2001

Population-based incidence of human granulocytic ehrlichiosis in northwestern Wisconsin, 1997-1999.

The incidence of human granulocytic ehrlichiosis (HGE) in the upper Midwest is uncertain. Active surveillance for suspected HGE was conducted from 1997 through 1999 in a 13-county region of northwestern Wisconsin. Suspected HGE cases were classified, according to the national case definition, as confirmed, probable, or not HGE. In total, 112 confirmed cases and 30 probable cases of HGE were identified. The median age of the 142 case patients was 56 years, and 92 (65%) were male; 111 (78%) were residents of the surveillance region. The mean annual incidence of confirmed and probable HGE was 9.3 cases per 100,000 residents; there was no increase from 1997 to 1999. The incidence was highest among persons > or =50 years old and residents of Washburn County. The incidence of HGE in this region exceeded prior estimates, but it was lower than the reported incidence in areas of endemicity in Connecticut.

Adolescent↗
PubMed2001

Pontiac fever due to Legionella micdadei from a whirlpool spa: possible role of bacterial endotoxin.

During January 1998, a cluster of illnesses occurred among hotel guests in Wisconsin. Ill persons had been exposed to the hotel's whirlpool spa and swimming pool. Symptoms included headache, fever, chills, myalgia, shortness of breath, and fatigue. A diagnosis of Pontiac fever was made, based on serologic evidence of acute infection with Legionella micdadei. High concentrations of heterotrophic bacteria were recovered from the spa, despite apparently high disinfectant levels. L. micdadei was isolated from the swimming pool filter and water from the spa after heat enrichment but not from pools and spas at nearby hotels. Water from hotel pools and spas was tested to determine endotoxin levels; water from the spa of the implicated hotel contained the highest concentration of endotoxin (14,400 endotoxin units/mL). Additional studies are needed to determine the role of endotoxin from legionellae or other bacteria in the pathogenesis of Pontiac fever.

Antibodies, Bacterial↗
PubMed2001

Modifying Mg2+ binding and exchange with the N-terminal of calmodulin.

To follow Mg2+ binding to the N-terminal of calmodulin (CaM), we substituted Phe in position 19, which immediately precedes the first Ca2+/Mg2+ binding loop, with Trp, thus making F19WCaM (W-Z). W-Z has four acidic residues in chelating positions, two of which form a native Z-acid pair. We then generated seven additional N-terminal CaM mutants to examine the role of chelating acidic residues in Mg2+ binding and exchange with the first EF-hand of CaM. A CaM mutant with acidic residues in all of the chelating positions exhibited Mg2+ affinity similar to that of W-Z. Only CaM mutants that had a Z-acid pair were able to bind Mg2+ with physiologically relevant affinities. Removal of the Z-acid pair from the first EF-hand produced a dramatic 58-fold decrease in its Mg2+ affinity. Additionally, removal of the Z-acid pair led to a 1.8-fold increase in the rate of Mg2+ dissociation. Addition of an X- or Y-acid pair could not restore the high Mg2+ binding lost with removal of the Z-acid pair. Therefore, the Z-acid pair in the first EF-hand of CaM supports high Mg2+ binding primarily by increasing the rate of Mg2+ association.

Amino Acid Substitution↗
PubMed2001

Burkholderia cepacia lower respiratory tract infection associated with exposure to a respiratory therapist.

OBJECTIVE: To investigate and control a nosocomial outbreak of Burkholderia cepacia lower respiratory tract infection. DESIGN: Outbreak investigation and case-control study. SETTING: A 260-bed community hospital. PATIENTS: Participants were mechanically ventilated intensive care patients without cystic fibrosis. A case was defined as a hospitalized patient with a sputum culture positive for B. cepacia between January 1 and November 6, 1998. METHODS: Respiratory therapy infection control policies and practices were reviewed; laboratory and environmental studies and a retrospective case-control study were conducted. Case-patients were matched with control-patients on age, gender, diagnosis, and type of intensive care unit. RESULTS: Nine case-patients were identified; B. cepacia likely caused pneumonia in seven and colonization in two. Two respiratory therapy practices probably contributed to the transmission of B. cepacia: multidose albuterol vials were used among several patients, and nebulizer assemblies often were not dried between uses. B. cepacia was grown from cultures of three previously opened multidose vials; pulsed-field gel electrophoresis patterns of B. cepacia from seven case-patients and two multidose vials were indistinguishable. Case-patients had longer durations of heated humidified mechanical ventilation (mean, 9.8 days vs 4.4 days; P=.03) and were more likely to have exposure to one particular respiratory therapist than controls (odds ratio, undefined; 95% confidence interval, 4.7-infinity; P=.001). The association with the respiratory therapist, a temporary employee, persisted after controlling for duration of heated humidified ventilation. No new B. cepacia infections were identified after control measures were implemented. CONCLUSIONS: B. cepacia probably was transmitted among patients through use of extrinsically contaminated multidose albuterol vials. Respiratory therapy departments must pay close attention to infection control practices, particularly among new or temporary staff.

Aged↗
PubMed2001

Multistate outbreak of Salmonella serovar Muenchen infections associated with alfalfa sprouts grown from seeds pretreated with calcium hypochlorite.

During September 1999, a multistate outbreak of Salmonella serovar Muenchen infection associated with eating raw alfalfa sprouts was identified in Wisconsin. Despite use of a calcium hypochlorite sanitizing procedure to pretreat seeds before sprouting, at least 157 outbreak-related illnesses were identified in seven states having sprouters who received alfalfa seed from a specific lot. The continued occurrence of sprout-related outbreaks despite presprouting disinfection supports the concern that no available treatment will eliminate pathogens from seeds before sprouting and reinforces the need for additional safeguards to protect the public. A lack of consumer knowledge regarding exposure to sprouts documented in this investigation suggests that more-targeted outreach to high-risk individuals may be needed to reduce their risk.

Adolescent↗
PubMed2001

Understanding screening: requirements for a successful programme.

Screening has generally been successful in identifying those at risk from disease. This success has led to the belief that screening in the general population is always a good thing. However, there are pitfalls which must be avoided if screening programmes are to achieve what is intended for them.

Cost-Benefit Analysis↗
PubMed2001

Understanding sampling: representativeness matters.

Sampling, or selecting a group of people to represent a whole population, lies at the heart of almost all research designs. There are many ways of going about this, each of which presents its own problems. The trick is to obtain a good-sized sample that is truly representative of the population as a whole.

Humans↗
PubMed2001

The effect of a community intervention trial on parental knowledge and awareness of antibiotic resistance and appropriate antibiotic use in children.

BACKGROUND: Overuse of antibiotics for children's upper respiratory infections is widespread and contributes to the emergence of antibiotic-resistant bacteria. OBJECTIVE: To assess changes in knowledge and awareness regarding antibiotic resistance and appropriate antibiotic use after community-wide educational interventions to reduce inappropriate antibiotic use. DESIGN: Baseline survey conducted during June through July 1997 and postintervention survey of baseline participants during June through August 1998. SETTING: Communities in northern Wisconsin. PARTICIPANTS: Parents of 729 randomly selected children <4 years of age were called until 215 in each of the intervention and control areas were reached. Of the 430 baseline participants, 365 (85%) participated in the postintervention survey. INTERVENTION: Parent-oriented activities included distribution of materials and presentations. Physician-oriented activities included formal presentations and small group meetings. OUTCOME MEASURE: Change in awareness about antibiotic resistance and knowledge about antibiotic indications. RESULTS: A higher proportion of parents in the intervention area (53%) were exposed to 2 or more local educational messages, compared with the control area (23%). From the baseline to the postintervention survey, the percentage of parents with a high degree of antibiotic resistance awareness increased more in the intervention area (58% to 73%) than in the control area (60% to 65%). In the intervention area, there was also a larger increase in knowledge regarding appropriate indications for antibiotic use, compared with the control area. The proportion of parents who expected an antibiotic for their child and did not receive one declined in the intervention area (14% to 9%), while it increased in the control area (7% to 10%). In addition, the percentage of parents in the intervention area who brought their child to another physician because they did not receive an antibiotic decreased (5% to 2%), while it increased in the control area (2% to 4%). CONCLUSION: Parental knowledge and awareness about antibiotic indications and antibiotic resistance can be changed with educational interventions directed at parents and clinicians.

Adult↗
PubMed2001

Impact of the Joint Statement by the American Academy of Pediatrics/US Public Health Service on thimerosal in vaccines on hospital infant hepatitis B vaccination practices.

OBJECTIVE: To determine the impact of the American Academy of Pediatrics/US Public Health Service (AAP/USPHS) joint statement on thimerosal in vaccines on hospital infant hepatitis B vaccination policies in Wisconsin. METHODS: The nurse managers of hospital newborn nurseries (n = 110) were surveyed by mail. Nonresponders were resurveyed. Twelve hospitals no longer provided obstetric services. Of the remaining 98 hospitals, 84 (86%) responded to the initial mailing and 14 (14%) responded to the second mailing. The number of hospitals that offered hepatitis B vaccine to infants before July 1999 was compared with that in March 2000. The number of hospitals that had policies in place to vaccinate infants whose mothers' hepatitis B surface antigen status (HBsAg) was positive or unknown during the thimerosal alert (July 1999 through November 1999) was compared with that in March 2000. RESULTS: Before July 1999, 81% of the hospitals representing 84% of reported Wisconsin births routinely offered hepatitis B vaccine to all infants. By March 2000, 50% of hospitals, representing 43% of births, had resumed routine infant hepatitis B vaccination. Physician decision to use a combination Haemophilus influenzae type b hepatitis B vaccine was the most frequently given reason for not reinstituting infant hepatitis B vaccination. During the thimerosal alert, 23% of hospitals did not have policies to vaccinate infants whose mothers were HBsAg-positive and 51% did not have policies to vaccinate infants whose mothers' HBsAg status was unknown. By March 2000, 6% of hospitals still did not have policies to vaccinate infants whose mothers were HBsAg-positive and 24% did not have policies to vaccinate infants whose mothers' HBsAg status was unknown. CONCLUSION: The AAP/USPHS joint statement on thimerosal in vaccines has resulted in a 38% decrease in the number of hospitals routinely offering infants hepatitis B vaccine. Although thimerosal-free hepatitis B vaccine is now available, some hospitals still do not have appropriate policies in place for vaccinating infants whose mothers' HBsAg status is positive or unknown. In the future, policymakers should include anticipated consequences that may result from changes in immunization policy in their recommendations.

Academies and Institutes↗
PubMed2000

Acid pairs increase the N-terminal Ca2+ affinity of CaM by increasing the rate of Ca2+ association.

A series of N-terminal calmodulin (CaM) mutants was generated to probe the relationship between the N-terminal Ca(2+) affinity and the number of paired, negatively charged Ca(2+) chelating residues in the N-terminal Ca(2+)-binding sites of CaM. When the number of acid pairs [negatively charged residues at positions +x and -x (X-axis), +y and -y (Y-axis), and +z and -z (Z-axis)] was increased from zero to one and then to two, a progressive increase was seen in the N-terminal Ca(2+) affinities. The maximal ranges of the increases observed in the N-terminal Ca(2+) affinity were approximately 8-8.5-fold for site I, approximately 4.5-5-fold for site II, and approximately 11-fold for both sites, in comparison to the mutants containing no acid pairs. The maximal values of N-terminal Ca(2+) affinity were bestowed by the presence of five acidic chelating residues in site I or II, individually. Addition of the sixth acidic chelating residue (third acid pair) to both N-terminal Ca(2+)-binding sites reduced the N-terminal Ca(2+) affinity. The increases in Ca(2+) affinity observed were caused by an increase in the Ca(2+) association rates for the Y- and Z-axis acid pairs, while the X-axis acid pair caused a reduction in the Ca(2+) dissociation rates.

Animals↗
PubMed2000

The three mechanisms of intracellular chloride accumulation in vascular smooth muscle of human umbilical and placental arteries.

Recordings of membrane potential (Em) and intracellular [Cl-] ([Cl-]i) were made from the smooth muscle of human umbilical and placental arteries, using double-barrelled, ion-sensitive microelectrodes. In both arteries, [Cl-]i was above equilibrium with Em. In the umbilical artery, [Cl-]i was 33.8+/-0.9 mM (+/-SD, n=19) and Em -54.9+/-1.3 mV and in the placental artery respectively 35.1+/-0.7 mM (n=17) and -50.6+/-0.9 mV. In both arteries, [Cl-]i was reduced and Em hyperpolarised significantly by successive additions of 100 microM 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulphonic acid (DIDS), 10 microM bumetanide and 1 mM acetazolamide, thus revealing the presence of Cl-/HCO3- exchange, (Na+K+Cl) cotransport and "pump III". In the presence of all three inhibitors, [Cl-]i was in equilibrium with Em. As in earlier studies on rat arterial smooth and cardiac muscle, pump III was unaffected by DIDS, bumetanide, metolazone and the removal of Na+, partly inhibited by chlorothiazide and fully inhibited by ethacrynic acid. The results are discussed in terms of the possibility that of chloride accumulating systems may regulate vasomotor tone in the foetoplacental unit.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2000

Juvenile xanthogranuloma of the nasal cavity.

Juvenile xanthogranuloma is a benign, normolipaemic, self-healing condition and a type of histiocytosis that occurs most frequently in infants and children. This condition usually presents with solitary or multiple cutaneous lesions and occasionally with visceral lesions. We report a case of juvenile xanthogranuloma occurring in the nasal cavity. We believe this is the first report, in the English literature, of juvenile xanthogranuloma occurring in this site.

Adolescent↗
PubMed2000

Escherichia coli O157:H7 infections in Wisconsin, 1992-1999.

Escherichia coli O157:H7 infection became a reportable condition in Wisconsin on April 1, 2000; previously cases were voluntarily reported by physicians and laboratories. During 1992 through 1999, 1333 cases of E. coli O157:H7 infection occurred in Wisconsin residents and were reported to the Wisconsin Division of Public Health. During this interval, the highest age-specific mean annual incidence, 13.2 cases per 100,000 population, occurred in persons 3 to 5 years old. Only 28% of patients with reported cases identified bloody diarrhea among their signs and symptoms. Of reported cases, 17% (231/1333) were involved in the eight outbreaks investigated during this interval. Among case patient identifiable risk exposures, farm related (13.4%), recreational water related (8.1%), and unpasteurized milk/dairy product (7.0%) exposures were the most frequently noted. Relatively few infections involved raw/undercooked ground beef consumption (5.8%). Recent use of pulsed-field gel electrophoresis has facilitated linkage of sporadically reported cases into recognized outbreaks. E. coli O157:H7 infections frequently occur in Wisconsin; acquisition of these infections in a wide variety of settings poses important challenges to their prevention and control.

Adolescent↗