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Biomedical subjects

G Taylor

Publications and source records attributed to G Taylor.

At least 541 records · Page 30Linked to original sources
PubMedDate not supplied

Juvenile myelomonocytic leukemia and Noonan syndrome.

A case of juvenile myelomonocytic leukemia (JMML, previously referred to as JCML) in a neonate with Noonan syndrome (NS) is described. The boy presented with bilateral congenital hydrothoraces, nonimmune hydrops, dysmorphic facies, persistent thrombocytopenia, and leukocytosis. The diagnosis of JMML was made on bone marrow cell culture studies. Review of the literature reveals an unusual preponderance of hematologic malignancies, in particular JMML, among patients with NS. Of 40 NS patients admitted to the authors' institution during a 10-year period, there were 4 (10%) with evidence of a monocytic proliferation, which resolved spontaneously. The authors postulate that patients with NS may have an increased incidence of myeloproliferative disorders, which in most cases appears to be benign but may be preleukemic or even lethal.

Adult↗
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Human papillomavirus absence predicts normal cervical histopathologic findings with abnormal papanicolaou smears: a study of a university-based inner city population.

INTRODUCTION: We studied the role of human papillomavirus (HPV) typing in predicting cervical dysplasia in women with abnormal Papanicolaou (Pap) test results. STUDY DESIGN/METHODS: A university colposcopy clinic-based consecutive sample of 179 women completed a questionnaire and underwent colposcopy, HPV typing (Hybrid Capture System HPV DNA Assay II; Digene Diagnostics, Gaithersburg, MD, USA), and biopsy (if indicated). RESULTS: No severe dysplasia was observed in women with low-risk HPV or in women with negative HPV test results who had a low-grade abnormality on the Pap test. High-risk (HR) HPV was present in every case of severe dysplasia on biopsy. The cumulative odds risk for cervical dysplasia was 1.11 in HIV(+) women with low-grade squamous intraepithelial lesion on the Pap test who were older than 21 years of age and HPV-HR(+). CONCLUSIONS: In the population studied, HPV typing is a valuable adjunct to a low-grade abnormality on the Pap test in predicting the absence of cervical dysplasia on biopsy. Larger prospective population-based studies are needed to study the role of HPV as a negative predictor of disease in cervical dysplasia.

Adolescent↗
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Dental erosion associated with asymptomatic gastroesophageal reflux.

An eight-year-old girl presented with severe erosion of the primary dentition and early erosion of the erupted permanent teeth. Although the pattern of erosion was consistent with that seen with acid erosion, the diagnosis could not be elucidated from the patient's symptoms, or medical or dental history. A 24-hour pH probe study documented severe gastroesophageal acid reflux. Oral salivary pH tested during sleep nightly for one week revealed low oral pH. Treatment with metoclopramide and ranitidine was instituted to decrease acid availability for reflux. Custom-fitted, maxillary and mandibular trays were fashioned to deliver sodium fluoride gel twice daily, and fissure sealants were placed in the hopes of retarding erosion of existing permanent teeth, as well as preventing similar erosion of erupting permanent dentition.

Child↗
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Interferon reduces hepatic drug metabolism in vivo in mice.

The effects of two highly purified human leukocyte interferons (IFN-A and IFN-AD) on drug-metabolizing capacity in mice have been investigated. IFN-AD was found to produce significant changes in antipyrine half-life, assessed by analysis of 14CO2 exhalation rates following 14C-antipyrine administration. By contrast, IFN-A, which has considerably less antiviral potency than IFN-AD, was found to have no effect on antipyrine half-life. The administration regimen was found to markedly alter the effects seen with IFN-AD. When IFN-AD was given as single daily doses (5 X 10(7) units/kg/day X 3 days), the half-life of antipyrine increased by a mean of 40% (from 21.0 to 28.9 min). However, when a smaller daily dose (3 X 10(7) units/kg/day) was given as a continuous infusion, the antipyrine half-life increased by more than 3-fold (from 20.8 to 68.5 min) after 3 days of administration. Continued infusion for a further 3 days produced no additional change in antipyrine half-life. These results demonstrate that human leukocyte interferons can significantly inhibit hepatic metabolic activity in vivo.

Animals↗
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Possible hemodynamic basis to urethane anesthesia-induced reductions in renal clearance.

The hemodynamic basis of reported urethane anesthesia-induced reductions in the clearance of some renally eliminated compounds has been investigated in the laboratory rat. The use of urethane as an anesthetic in pharmacokinetic studies still persists, particularly in experiments of long duration. Using a microsphere technique, the per cent distribution of cardiac output to the kidneys, in both ip urethane- and ip Hypnorm/Hypnovel-anesthetized animals was significantly (p less than 0.01) lower than that observed in ip pentobarbital-anesthetized animals. However, the cardiac index in the Hypnorm/Hypnovel-anesthetized animals was 42% greater (p less than 0.01) than in the pentobarbital-treated animals and 86% greater (p less than 0.01) than in the urethane-treated group. Additionally, the cardiac index in the pentobarbital-anesthetized animals was significantly greater (p less than 0.01) than in the urethane-anesthetized animals. The lower cardiac index and reduced cardiac distribution to the kidneys in the urethane-treated group resulted in significant (p less than 0.01) reductions of approximately 40% in renal blood flow and glomerular filtration rate compared with the animals anesthetized with pentobarbital or Hypnorm/Hypnovel. The transport capacity of the basolateral organic anion secretory mechanism was not compromised by an ip injection of urethane, as demonstrated by p-aminohippuric acid transport studies conducted in isolated renal tubule fragments prepared from anesthetized animals. In conclusion, urethane anesthesia results in significant alterations of renal hemodynamics compared with pentobarbital and Hypnorm/Hypnovel anesthesia in the rat. For primarily renally eliminated compounds, such alterations are likely to influence pharmacokinetic data generated using this anesthetic agent.

Anesthesia↗
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The renin-angiotensin system and intraperitoneal toxicity: possible basis to urethane anaesthesia-induced reductions in renal clearance in the rat.

With the aim of examining the possible basis to i.p. urethane anaesthesia-induced reductions in renal clearance, this study has investigated: (a) the influence that some anaesthetic regimens may have on the renin-angiotensin system (RAS); and (b) the ability of these anaesthetic regimens to initiate intraperitoneal toxicity. In the rat, i.p. urethane anaesthesia, compared with pentobaritone i.p. and "Hypnorm/Hypnovel" i.p. anaesthesia, resulted in significantly lower mean arterial pressure (MAP) and elevations in plasma renin activity (PRA) in both surgically-prepared and surgically-intact animals. Urethane anaesthesia also produced intraperitoneal toxicity, which was characterized by a greater peritoneal fluid volume and peritoneal cavity total protein content. The elevated protein content in the peritoneal cavity resulted in part from plasma leakage from the vascular compartment, as demonstrated by i.v. Evans' blue dye studies. Intraperitoneal toxicity was absent following administration of urethane by either i.v. or oral routes. A reduction in systemic perfusion pressure and an elevation in renal vascular resistance, via activation of the RAS are likely to be responsible for i.p. urethane-induced reductions in renal clearance. Intraperitoneal toxicity is likely, only in part, to be responsible for such changes.

Anesthesia↗
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Aminopyrine demethylation kinetics. Use of metabolite exhalation rates as an index of enhanced mixed-function oxidase activity in vivo.

The usefulness of determining aminopyrine demethylation kinetics via monitoring of metabolite exhalation rats had been assessed. In rats receiving [N-dimethyl-14C]aminopyrine, a biexponential decline in the 14CO2 exhalation rate is apparent when monitoring is continued over a 5 to 6-hr period. Both the fast phase (representing the first demethylation) and the slower phase (representing the second demethylation) are markedly influenced by phenobarbital and promethazine pretreatment. These changes are consistent with enhanced mixed-function oxidase activity. Examination of the urinary excretion products of aminopyrine obtained in these studies support this claim. The sensitivity of the above index of mixed-function oxidase activity is increased considerably by the use of crossover experimental designs. Considerable interanimal variation is observed in the metabolite production in both exhaled air and urine from rats administered aminopyrine.

Aminopyrine↗
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Interaction of mycoplasmas and phagocytes.

Aspects of the interaction of certain mycoplasmas with macrophages and neutrophils in vivo and in vitro have been studied using two systems, one involving M. pulmonis in mice and the other involving M. bovis with bovine leucocytes. Studies with M. pulmonis indicated that the disappearance of viable organisms from the peritoneal cavity was not enhanced in SPF mice in which a peritoneal exudate rich in neutrophils had been induced. However, viable M. pulmonis organisms disappeared more rapidly from the peritoneal cavities with exudates containing increased numbers of macrophages. Experiments in vitro studied the opsonic effect of bovine IgG isotypes for bovine neutrophils and alveolar macrophages. Both IgG1 and IgG2 promoted killing of M. bovis by alveolar macrophages but IgG2 was more effective than IgG1 at promoting mycoplasma killing by neutrophils. Further studies in vitro indicated that certain bovine mycoplasma could inhibit killing of Escherichia coli by bovine neutrophils.

Animals↗
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How to use a headhunter.

Using a headhunter to find a new position for yourself or to fill a vacancy in your institution is becoming increasingly popular in nursing. The author, now a headhunter who was formerly a practicing nurse, provides some ground rules for effectively and efficiently using a headhunter.

Consultants↗
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Cold comfort.

Explore the source record for details and available documents.

Aged↗
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Comparative flow rates of saline in commonly used spinal needles including pencil-tip needles.

BACKGROUND AND OBJECTIVES: Certain characteristics of spinal needles that can influence their clinical usefulness were examined, namely, flow rates, internal diameters, and size of orifices of pencil-type needles. METHODS: Flow rates of 0.9% sodium chloride solution were measured in spinal needles with an infusion pressure of 10 mmHg at isothermic and steady-state conditions. In 15 different types, a new needle was used for each experiment, and 6 experiments were performed with each needle type for a total of 90 experiments. The Hagen-Poisseuille Law for laminar flow was used to calculate the internal diameters. RESULTS: The flow rates of needles of the same gauge varied considerably depending on the manufacturer. Compared with 26-gauge ultrathin-wall spinal needle produced by the same manufacturer (Braun, Bethlehem, Pennsylvania), the flow rate through 29-gauge spinal needle was 18% that of the former needle. The flow rate through 27-gauge Quincke Whitacre needle (Becton Dickinson, Rutherford, New Jersey) was not statistically different from that through 26-gauge needle by the same manufacturer. By arbitrarily choosing < or = 2 seconds to be the in vitro desirable period for saline to traverse the needle from one end to the other, all needles with the exception of 29-gauge and standard 26-gauge Quincke Braun needles met this criterion. The length and size of the orifices of Whitacre needles were found to be significantly smaller than those of Sprotte needles (Havel, Cincinnati, Ohio). The orifice of Sprotte needle was longer than the known thickness of the dura while that of the Whitacre needle was smaller. CONCLUSIONS: Needles of the same gauge do not necessarily have the same flow rate. Flow rate correlates well with internal, not external, diameter. By considering < or = 2 seconds to be the desirable time for saline to traverse a spinal needle, all, except two, meet this criterion. The orifice of Whitacre needle has more desirable features than that of Sprottle needle. Anesthesiologists are encouraged to use 27-gauge needles since their flow rate is not slower than that of 26-gauge needles.

Needles↗
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Incidence of tissue coring with the 25-gauge Quincke and Whitacre spinal needles.

BACKGROUND AND OBJECTIVES: Tissue cores, implanted into the subarachnoid space during subarachnoid injections, can develop into intraspinal lumbar epidermoid tumors. The availability of smaller needles has made spinal anesthesia more popular. Therefore, this prospective, randomized, blinded study was undertaken to determine whether tissue coring occurs with two of the currently used 25-gauge spinal needles. METHODS: Fifteen 25-gauge Quincke and seventeen 25-gauge Whitacre spinal needles, in which cerebrospinal fluid (CSF) was not identified and the local anesthetic solution not injected, were obtained from adult male patients undergoing spinal anesthesia. The needles were then evaluated by a pathologist following randomization with similar sterile, unused spinal needles. Twenty additional needles, ten of each type, in which CSF was identified and through which local anesthetic was injected, were also randomized with similar sterile, unused spinal needles and examined. RESULTS: Tissue cores were identified in 12 of the 15 Quincke and 7 of the 17 Whitacre spinal needles in which CSF was not identified (P < .05). Of the 20 needles in which CSF was identified and local anesthetic injected, no tissue cores were identified in the 10 Whitacre needles and only one small tissue core was identified in the 10 Quincke needles. All the tissue cores were identified as fat tissue. CONCLUSIONS: The 25-gauge Quincke and 25-gauge Whitacre spinal needles currently used in anesthesia can produce tissue coring.

Adult↗