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Biomedical subjects

C Brooks

Publications and source records attributed to C Brooks.

At least 37 records · Page 2Linked to original sources
PubMed1997

A left free-wall, decrementally conducting, atrioventricular (Mahaim) fiber: diagnosis at electrophysiological study and radiofrequency catheter ablation guided by direct recording of a Mahaim potential.

A 64-year-old female with Wolff-Parkinson-White syndrome and an ECG demonstrating a right posterolateral accessory pathway was referred for electrophysiological study. During electrophysiological testing two AV pathways were identified: a right posterolateral pathway that displayed conventional electrophysiological properties: and a left free-wall pathway that conducted only anterogradely and demonstrated decremental properties. Two separate wide complex tachycardias were induced that utilized the left free-wall pathway anterogradely and either the AV node or the right posterolateral accessory pathway retrogradely. A discrete electrical potential on the free wall of the mitral annulus was identified during tachycardia and was utilized to facilitate mapping and ablation.

Atrioventricular Node↗
PubMed1997

Neonatal hypoglycemia.

Neonatal hypoglycemia is a common phenomenon in the newborn infant. The neonatal nurse has the primary responsibility for identifying infants at risk and early warning signs. This article outlines the definition, central nervous system symptomatology, incidence, risk factors, etiology, and pathophysiology of low blood glucose levels. An understanding of the three basic mechanisms of glucose homeostasis-glycogenolysis, glycolysis, and glyconcogenesis-is crucial for the nurse caring for any newborn infant, particularly those at risk. All personnel involved in blood sampling must be carefully trained; proper screening and laboratory blood sampling techniques for glucose measurement cannot be overemphasized. Inaccurate results produced by faulty techniques can lead to misdiagnosis and improper treatment. A plan of care including glucose screening on initial assessment and follow-up must be, considered whenever hypoglycemic symptoms are observed or risk factors are present. Knowledge of appropriate interventions and outcome evaluation for hypoglycemia is the responsibility of the neonatal nurse.

Humans↗
PubMed1996

Developmental profile of plasma inhibin and gonadotropins from hatch to sexual maturity in male and female chickens.

The posthatch profiles of plasma immunoreactive inhibin and gonadotrophins (FSH and LH) were examined in male and female chickens. Blood samples were collected and hormones were measured by radioimmunoassay at biweekly intervals from Week 1 through Week 19 (Week 21 in females) posthatch. Immunoreactive inhibin was elevated (P < 0.01) in males between Weeks 7 and 15. In contrast, immunoreactive inhibin was significantly elevated (P < 0.001) in females at 17 and 19 weeks compared to earlier time points. There was no significant difference in FSH level between males and females. Both sexes showed a significant (P < 0.01) rise in FSH during development. Males had significantly higher levels of LH compared to females. While there was no change in LH throughout 19 weeks in females, plasma LH was significantly elevated in males at 7, 11, 13, and 15 weeks. Results suggest that a negative relationship between inhibin and FSH may be established in females, in contrast to males, at the onset of puberty.

Animals↗
PubMed1996

Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study.

A pilot phase I study was conducted with a cyclic heptapeptide analog of alpha-melanocyte stimulating hormone (alpha-MSH). The lactam-bridged molecule, called Melanotan-II (MT-II), has the structure Ac-Nle4-Asp5-His6-D-Phe7-Arg8-Trp9-Lys10 alpha-MSH4-10-NH2 (MT-II) and has superpotent melanotropic activity in vitro. A single-blind, alternating day (saline or MT-II), placebo-controlled trial was conducted in 3 normal male volunteers at the starting dose of 0.01 mg/kg of MT-II. Subcutaneous injections of MT-II or saline were given daily (Monday-Friday) for 2 consecutive weeks. Two subjects were escalated by 0.005 mg/kg increments to 0.03 mg/kg and one to 0.025 mg/kg. The 0.03 mg/kg dose produced Grade II somnolence and fatigue in one of two subjects (WHO standards). Mild nausea, not requiring antiemetic treatment, was reported at most MT-II dose levels. A stretching and yawning complex appeared to correlate with the onset of spontaneous, penile erections which were intermittently experienced for 1-5 hours after MT-II dosing, depending on the MT-II dose. Two subjects had increased pigmentation in the face, upper body and buttock, as measured by quantitative reflectance and by visual perception 1 week after MT-II dosing ended. These results demonstrate that MT-II has tanning activity in humans given only 5 low doses every other day by subcutaneous injection. The recommended single MT-II dose for future Phase I studies is 0.025 mg/kg/day.

Adult↗
PubMed1996

Drug and Therapeutics Committees in Australia: expected and actual performance.

1. This study describes stakeholders' opinions on Drug and Therapeutics Committees (DTCs) and measures the composition, activities and perceived effectiveness of DTCs in Australia. 2. Focus groups explored the opinions of clinicians, consumers and administrators on the goals, objectives and strategies of DTCs. 3. A national survey was sent to 306 hospitals to collect data on the composition, committee processes, goals, objectives, educational activities, policies and decision making of DTCs. 4. Stakeholders believed the DTC should optimise therapeutic health outcomes for patients and economic outcomes for the hospital. Important objectives were availability of safe, efficacious and cost-effective medicines, affordability of medicines and quality use of medicines. 5. The national survey of DTCs found that over 92% of respondents had a DTC in their hospital. Composition was generally representational and most commonly included members from the disciplines of internal medicine, pharmacy and nursing. More than half the DTCs had executive authority although only 21% had an appeals mechanism. 6. The most commonly cited issues for DTCs in 1994-95 were quality drug use, drug policies and spending on high cost drugs. 7. While access to clinical pharmacologists and specialist drug utilisation evaluation (DUE) pharmacists was poor, 71% of DTCs had access to DUE data of some sort. Guidelines (61%), prescribing restrictions (60%) and pharmacist monitoring (63%) were the most commonly used strategies to implement DTC policies and decisions. Audit-feedback activities (61%) and drug bulletins (56%) were the most commonly used interventions. 8. Available information for formulary decision making varied with small rural hospitals having access to significantly less information. The most commonly used information was availability of a therapeutic alternative (87%), efficacy (83%), cost (80%) and estimated usage (78%). 9. On average DTCs reported an ability to implement 75% of decisions (range 0-95%) with teaching hospitals perceived to perform better than other hospital types. 10. This study reveals a high level of expectation for DTC activities and achievements. In Australia DTCs were involved in policy, education and management initiatives to promote best practice in therapeutics. Few committees appeared to have adequate resources to extend services to their wider community.

Australia↗
PubMed1996

The biting midge of the West Highlands: fifty years of research.

The biting midge of the West Highlands belongs to the family Ceratopogonidae and approximately 150 species are known to exist in Britain. All of the flies are of minute size and slender build with wings which fold over the back. The females have biting mouthparts including a needle sharp proboscis with scissor type mandibles. The males do not bite. The Ceratopogonidae devours other small insects, some feed on plant juices, others pierce the wing veins of butterflies and some attack juicy caterpillars. Only three genera are bloodsuckers and of these only Culicoides occurs in Britain. The members of this genus are classified by the pattern of wing venation and the spots on the wings. Edwards' gives a detailed table of these characteristics. The commonest species in Scotland is C. impunctatus, although others have been met with on Skye.

Animals↗
PubMed1995

Growth impairment resulting from expression of influenza virus M2 protein in Saccharomyces cerevisiae: identification of a novel inhibitor of influenza virus.

The gene encoding M2, the ion channel-forming protein of influenza virus A, was expressed under the control of an inducible promoter in Saccharomyces cerevisiae. By using single and multicopy plasmids containing GAL promoter-M2 fusions, a correlation was observed between plasmid copy number and growth in medium inducing M2 expression. Cells expressing M2 from multicopy plasmids have reduced growth rates, suggesting that high levels of M2 are toxic to growth. The addition of amantadine, a compound known to block the ion channel activity of certain M2 alleles, restores the growth rates to wild-type levels in cells expressing an amantadine-susceptible allele of M2 but not an amantadine-resistant allele of M2, suggesting that M2 expression in S. cerevisiae results in the formation of functional M2 ion channels. Measurements of extracellular acidification by microphysiometry suggest that proton efflux in M2-expressing cells is altered and that the addition of amantadine permits the reestablishment of the proton gradient. The growth impairment phenotype resulting from M2 expression was used to develop a high-capacity screening assay which identified a novel inhibitor possessing an antiviral profile similar to that of amantadine.

Amantadine↗
PubMed1994

Purification and biochemical characterization of recombinant N-methylpurine-DNA glycosylase of the mouse.

The mouse N-methylpurine-DNA glycosylase (MPG), responsible for the removal of most N-alkyladducts in DNA, was purified to homogeneity as a recombinant nonfusion protein from Escherichia coli. Only 10-15% of the protein was present in the soluble form in E. coli cells. The N-terminal amino acid sequence of the purified protein which lacks 48 residues from the amino terminus of the wild type protein was identical to that predicted from the nucleotide sequence. The glycosylase hydrolyzes 3-methyladenine (m3A), 7-methylguanine(m7G), and 3-methylguanine (m3G) from DNA, and the Km and kcat values were 130 nM and 0.8 min-1 for m3A, and 860 nM and 0.2 min-1 for m7G, respectively, when methylated calf thymus DNA was used as the substrate. A comparison of kcat/Km values for different bases indicates that the enzyme was more efficient in excising both m3A and m3G than m7G from methylated DNA. The enzyme showed moderate binding affinities (KA) for both methylated (5.8 x 10(7) M-1) and nonmethylated DNAs (4.2 x 10(7) M-1). The mouse protein has an extinction coefficient E280nm1% of 10.5 and a pI of 9.3. The enzyme activity was optimal in the presence of 100 mM NaCl, with a broad pH optimum of 8.5-9.5. The enzymatic release of both m3A and m7G was stimulated 50-75% by 0.5 mM MgCl2 and 0.02 mM spermine but inhibited by higher concentrations of these agents. Product inhibition by 40-50% of the reaction occurred in the presence of 10 mM m3A or m7G. However, 1.0 mM m3A stimulated release of m7G. The enzyme was inhibited by 60% in the presence of 0.9 mg/mL DNA which, at the same time, protected it from thermal inactivation.

Adenine↗
PubMed1993

Characterization of a source and levels of plasma immunoreactive inhibin during the ovulatory cycle of the domestic hen.

The domestic hen with its well-organized follicular hierarchy offers a unique model system for the study of the role of inhibin in follicular development. We have validated a homologous bovine RIA for use in the hen to measure plasma immunoreactive inhibin-like activity during the ovulatory cycle as well as during experimental conditions in which follicular development has been altered. Validation of the bovine RIA kit revealed that increasing amounts of hen plasma gave linear increases in the amount of immunoreactive inhibin detected. This assay system as well as a homologous chicken LH RIA were used to assess plasma concentrations of immunoreactive inhibin and LH, respectively, in experiments 1-3. In experiment 1, blood samples were collected from hens (n = 5) at 2-h intervals for 24 h starting at 1600 h after the lay of the last egg of the sequence through the following day. No significant peak in plasma immunoreactive inhibin level was detected during the ovulatory cycle, in spite of a significant preovulatory rise in plasma LH. The highest level of plasma immunoreactive inhibin was attained, however, 2 h prior to the preovulatory LH surge. In experiment 2, eCG (n = 6) or vehicle (n = 3) was administered to hens daily for 6 days. A blood sample was drawn immediately before injection each day as well as 24 h after the last day of treatment. Treatment with eCG significantly (p < 0.01) raised plasma immunoreactive inhibin-like levels, compared to vehicle-injected controls. In experiment 3, three to four of the largest follicles (F1-F4) were surgically removed, or sham surgery was performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Plasma concentrations of immunoreactive inhibin and gonadotropins following removal of ovarian follicles in the domestic hen.

In the domestic hen, the preovulatory follicles are arranged in a hierarchy. The largest (F1) follicle ovulates first, the second largest (F2) follicle ovulates approximately 26 h later, and so on. The nature of this regulation is not known. Inhibin has been implicated in the feedback regulation of FSH in mammals, and bioactive as well as immunoreactive inhibin has been demonstrated in chickens. The present experiments were conducted with two aims: 1) to determine the plasma level of immunoreactive inhibin in response to removal of various numbers of preovulatory follicles and 2) to assess the gonadotropin response to such follicle removal. In experiment 1, the F1 (n = 4), F1 + F2 (n = 5), F1 + F2 + F3 (n = 5), and F1 + F2 + F3 + F4 (n = 4) follicles were removed surgically. Sham-operated animals served as controls. Blood samples were taken at time 0 (prior to surgery) and at 6, 24, and 48 h after surgery. In experiment 2, animals were sham-operated (n = 5) or the F1-F4 (n = 4) or F1-F4 plus small yellow follicles (SYF; n = 5) were removed. Blood samples were removed at time 0 and at 3, 6, and 24 h and at daily intervals until Day 10 after surgery. In both experiments, plasma immunoreactive inhibin was significantly lowered (p < 0.001) and plasma FSH was acutely increased (p < 0.05) by follicle removal. Plasma LH was decreased at some time points after follicle removal.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Adult respiratory distress syndrome. A complication of shock.

ARDS is a complex type of respiratory failure that usually is a complication of a catastrophic critical illness, such as shock. Mortality is high, especially in patients with septic shock and multisystem failure. Mortality often is related to complications of refractory hypoxemia. Identifying patients at risk for developing ARDS and early recognition of ARDS are important so that treatment can be initiated to prevent the potentially lethal consequences of refractory hypoxemia. The nurse has an important role in collaborating with the physician and respiratory therapist to support the patient's oxygenation, ventilation, and tissue oxygen delivery system. The nurse is responsible for performing highly sophisticated assessment of clinical and hemodynamic parameters to evaluate the effectiveness of therapy. A key role of the nurse is anticipating, recognizing, and reporting to the physician complications of hypoxemia and complications of therapy that can lead to sepsis, airway trauma, or failure of other organ systems.

Humans↗
PubMed1989

Idealism and realism in patient care during radiotherapy treatment.

Previous research has demonstrated that typification of patients by health workers is inevitable even when these workers aspire to a concept of treating each patient as an individual. This study aimed to establish how six therapy radiographers, working in three different settings, typified their cancer patients and how this related to their concept of role and the environment in which they worked. The techniques used were ethnographic, non-directive interview techniques and naturalistic observation. There are interesting variations and similarities in how the individuals perceived their working role and environment and in their perception of patients. The typifications of patients by the therapy radiographers studied are related to and reflect the radiographers' concerns or stresses. They relate to the issues of information giving and receiving, control of the radiographer-patient relationship, how to cope with patient dependency and how this interacts with their own ideals and impression management. Some also reflect the problems experienced in working relationships, in particular balancing their own ideals with the reality of their working situation.

Age Factors↗
PubMed1988

Pacemaker failure associated with therapeutic radiation.

A 48-year-old white man with a multiprogrammable Intramedics 259-01 pacemaker was treated for inoperable lung cancer with a course of cobalt-60 radiotherapy (total 3,500 rad). Several weeks subsequent to his last radiation treatment, the patient presented to the emergency department with chest and abdominal pain, shortness of breath, hypotension, and tachycardia. A paced tachycardia was noted, and application of a magnet over the pacemaker completely inhibited its function, allowing a normal sinus rhythm to ensue and the patient's symptoms to be relieved. Pacemaker failure probably was a complication of radiotherapy.

Cobalt Radioisotopes↗