Biomedical subjects
C Harvey
Publications and source records attributed to C Harvey.
Imaging of terminal myelocystoceles.
This article presents a retrospective analysis of the presentation, imaging studies, and associated findings in 20 children with surgically and histologically proven terminal myelocystoceles. All 20 children presented at birth with a black mass; 13 had cloacal extrophy. The patient population was comprised of 15 girls and 5 with ambiguous genitalia: Of the imaging studies, 8 had plain radiographs, 6 myelography-computed tomography, 11 ultrasound, and 14 magnetic resonance. The associated findings included Chiari I (eight patients), Chiari II (one patient), hydromyelia (three patients), hydrocephalus (three patients), and vertebral segmentation anomalies (six patients). Magnetic resonance imaging was the best imaging modality to diagnose and evaluate children with a myelocystocele. Magnetic resonance imaging demonstrated the classic findings: a terminal cyst of the central canal of the spinal cord that is tethered and herniated with arachnoid and cerebrospinal fluid through an area of spinal dysphria onto the back as a mass.
MR of terminal myelocystoceles.
PURPOSE: To delineate the clinical and MR findings in children with an unusual type of spinal dysraphism, the terminal myelocystocele. Infants with a terminal myelocystocele carry a favorable neurologic prognosis if the entity is diagnosed early. Understanding the MR characteristics of this entity will allow for earlier and more accurate diagnosis. METHOD: Analysis of the medical charts and MR studies in 15 children with surgically and histologically proven myelocystocele. RESULTS: In all 15 children, MR demonstrated the primary findings of a terminal cyst of the central canal of the spinal cord which is tethered and herniated with arachnoid and cerebrospinal fluid through an area of spinal dysraphia onto the back as a mass. Of these children, 10 had additional findings (one or more) on MR of Chiari I (five cases), Chiari II (one case), cervicothoracic hydromyelia (two cases), lumbar hydromyelia (two cases), hydrocephalus (2 cases) segmentation anomalies of vertebrae (3 cases) and partial agenesis of sacrum (six cases). Of the clinical findings, all 15 children had a back mass, 10 also had cloacal exstrophy. One had imperforate anus, 10 were girls, five had ambiguous genitalia and all were neurologically intact. CONCLUSION: Children with a terminal myelocystocele present with a back mass and there is a high association with cloacal exstrophy. MR is the best noninvasive modality to diagnose all of the components of a terminal myelocystocele and the associated central nervous system findings.
Genotoxicity testing: current practices and strategies used by the pharmaceutical industry.
Current guidelines and recommendations for genotoxicity testing of pharmaceuticals are disparate, both in terms of the most appropriate tests to use and the protocols to follow. Recent attempts have been made to standardise genotoxicity testing procedures, coinciding with the current review of the OECD guidelines and the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). However, as with other aspects of non-clinical safety assessment of pharmaceuticals, guidelines have been prepared by evaluation of general chemical data due to the lack of specific information on pharmaceuticals. To address this, a project was undertaken to collect and collate information specifically pertaining to the genotoxicity testing of pharmaceuticals in order to obtain a clear understanding of international strategy and procedures in the pharmaceutical industry. It is clear that the practices and regional variations are strongly influenced by national guidelines and do not necessarily follow companies' preferences. However, there is a surprising amount of variation in approach between companies on some issues. This is evident in how companies define a genotoxin. This ranges from a positive result in an in vivo assay as indicative of a genotoxin (43%) to any positive result in vitro or in vivo (30%). Indeed many companies (particularly in Japan) will terminate development on the strength of a clear positive result in an Ames test. There is much debate within the ICH process concerning tests to detect gene mutations in mammalian cells as part of a primary test battery. This survey shows that in general, the pharmaceuticals industry has severe doubts about these assays. Thirty-seven (78%) of the 47 participating pharmaceutical companies include an in vitro test to detect gene mutation in mammalian cells as part of their routine test battery. The HPRT test using Chinese hamster cells has the most widespread use, although there is only limited use of such tests in Japan. Compound development has been affected by the results of such tests, but usually only in terms of clarification of equivocal results in other genotoxicity tests in the test battery. The majority (63%) of companies do not support its use as a primary regulatory requirement, and 83% do not consider the mouse lymphoma assay (L5178Y) an acceptable replacement for in vitro mammalian cytogenetics. In conclusion, this survey has provided valuable information on the current modus operandi of the international pharmaceutical industry for consideration in current harmonisation initiatives.
Defining characteristics of chronic disease.
Explore the source record for details and available documents.
Support group for families of trauma patients: a unique approach.
Explore the source record for details and available documents.
Regional localization of DPP4 (alias CD26 and ADCP2) to chromosome 2q24.
A panel of microcell hybrids containing fragments of chromosome 2 was analyzed for the presence of human DPP4, the gene that codes for dipeptidyl peptidase IV (or CD26), by specific PCR amplification of a fragment of the 3' untranslated region of the gene. This analysis placed DPP4 between LCT and GAD in bands q21 to q31. The localization was confirmed by in situ hybridization using two genomic probes that each revealed a hybridization signal in band q24. We also use the recent identification of the ADA binding protein as DPPIV to propose that the gene ADCP2 should be renamed DPP4.
Aerosol deposition in mechanically ventilated patients.
Explore the source record for details and available documents.
Expression of human intestinal mRNA transcripts during development: analysis by a semiquantitative RNA polymerase chain reaction method.
To study the relative expression of lactase, sucrase-isomaltase, dipeptidyl peptidase IV, and the Na(+)-dependent glucose transporter mRNA transcripts in small samples of human tissue, we have developed and validated a very simple semiquantitative RNA polymerase chain reaction method that can be used on as little as 5-10 mg of tissue. Here we report the use of this method to study the expression of these genes at different stages of development, in different tissues and in different parts of the intestine, in comparison with another intestinal marker, the colon-specific transcript of carbonic anhydrase 1. Lactase, sucrase-isomaltase, and the Na(+)-dependent glucose transporter mRNA are expressed predominantly in the small intestine, although lactase mRNA is expressed at a very low level in fetuses. Dipeptidyl peptidase IV mRNA shows a much wider tissue distribution. Sucrase-isomaltase and dipeptidyl peptidase IV mRNA are present at high levels in fetal colon and also at surprisingly high levels in adult colon. Lactase mRNA, on the other hand, is present at very low levels in fetal colon and is not detectable at all in adult colon. The Na(+)-dependent glucose transporter mRNA in contrast is expressed at higher levels in the adult colon than in the fetal colon. This is also the case for the carbonic anhydrase 1 transcript, although this transcript is not expressed in the small intestine. Thus, each of these genes shows different developmental and cell-specific regulation.
The practice patterns of adult oncologists' care of pediatric oncology patients.
The role of the adult oncologists in the area of pediatric cancer treatment previously has been unmeasured. A questionnaire bearing regarding the practice of 447 adult oncologists was administered in June 1991. The membership list of the Association of Community Cancer Centers was used to identify contact oncologists. One hundred thirty-one questionnaires (29.3%) were returned for analysis. The data reveal that 204 patients younger than 21 years of age were treated during the last year in 63 adult oncology practices. Most of these patients were more than 15 years of age. Only a minority (53) were treated in rural practices. In addition, only a minority (27%) of these patients are reported to be enrolled in clinical trials. In addition, adult oncologists appear to regard physiologically mature adolescents (age 16-21 years) as adults. They do not seem to make a distinction between patients 16-21 years old and those older than 21 years.
Carriage of Haemophilus influenzae type b in children after widespread vaccination with conjugate Haemophilus influenzae type b vaccines.
Rates of invasive Haemophilus influenzae type b (Hib) disease in children decreased very rapidly after licensure of Hib conjugate vaccines. A role for a vaccine-related reduction in nasopharyngeal carriage of Hib has been suggested. We studied oropharyngeal carriage of Hib and vaccination rates in a population of 2- to 5-year-old children in metropolitan Atlanta. Among 584 children 75% were vaccinated with an Hib conjugate vaccine, 17% had not been vaccinated and 8% had no vaccination records available. Forty-one percent of the children were colonized with H. influenzae. One child was colonized with Hib. Hib carriage (0.17%; upper 95% confidence interval boundary, 0.97%) was substantially lower than the estimates of Hib carriage from prior studies of children who had not received Hib conjugate vaccines. Our data are consistent with a decline in Hib carriage induced by widespread use of conjugate Hib vaccines, which may have contributed to the decline of Hib disease in United States children.
Rigors in tuberculosis.
Rigors are not a recognized characteristic of miliary tuberculosis. We report two patients presenting with persistent rigors, thought to be suggestive of acute pyogenic infection, who were subsequently found to have miliary tuberculosis. In both cases, there was significant diagnostic delay. Miliary tuberculosis should therefore be included in the differential diagnosis of any patient presenting with unexplained rigors.
Systemic antimicrobials in the treatment of periodontitis in dogs.
Periodontitis is a common condition in dogs. Treatment of periodontitis consists of mechanical removal of plaque and calculus by scaling, root planing, and polishing the teeth. Antimicrobial therapy can provide additional improvement in severe or refractory cases of periodontitis when combined with dental prophylaxis if ongoing plaque control is not provided. The ability of various antimicrobials to reach therapeutic levels in the periodontal tissues differs greatly. The efficacy of antimicrobials against common periodontal pathogens also varies greatly. Choosing an appropriate antibiotic to treat periodontitis should be based on these considerations. Amoxicillin-clavulanate, clindamycin, and nitroimidazoles, such as metronidazole and tinidazole, seem to be particularly effective based on pharmacokinetic and clinical studies.
New estimates of the direct costs of traumatic spinal cord injuries: results of a nationwide survey.
New estimates of the direct costs of traumatic spinal cord injuries (SCI) are obtained from a comprehensive survey of the US SCI population. These direct costs, defined as the value (in 1988 dollars) of resources used specifically to treat or to adapt to the SCI condition, represent the average experience of the US SCI population. Responses to a detailed questionnaire administered to a sample of traumatic SCI persons in the United States provide the primary source of data for this study. Analysis of this survey data indicates that more recently injured SCI persons (ie those injured since 1970) spent an average of 171 days in a hospital over the first 2 years post injury. Initial hospital expenses will average $95,203. Home modification costs in excess of $8,000 can also be expected. After recovery and rehabilitation, a SCI person will pay, on average, $2,958 per year in hospital expenses and $4,908 per year for other medical services, supplies and adaptive equipment. Personal assistance costs and costs of institutional care will average $6,269 per year. These cost estimates represent the incremental costs of SCI, ie they exclude any costs that would have been incurred in the absence of SCI.
Potassium channel activators cromakalim and celikalim (WAY-120,491) fail to decrease myocardial infarct size in the anesthetized canine.
The cardioprotective effects of the K channel activator drugs celikalim (WAY-120,491) and cromakalim were studied in a canine model of myocardial infarction consisting of 90 min of ischemia and 5 h of reperfusion. Intracoronary infusion of cromakalim and celikalim at 0.2 microgram/kg/min beginning 10 min before occlusion of the left circumflex coronary artery and continuing throughout the duration of the reperfusion period appeared to exacerbate ischemic injury. Infarct size (percent of risk area) was 27.7 +/- 5.6% in vehicle control animals (n = 5), 40.3 +/- 6.2% for cromakalim (n = 5) and 55.7 +/- 6.4% (p less than 0.05 vs. vehicle) for celikalim-treated animals (n = 5). When these compounds were administered intravenously, using doses shown to increase total coronary flow in nonoccluded control animals, no exacerbation of ischemic injury was observed. Anatomic infarct size was 32.8 +/- 7.1% for vehicle animals (n = 5) and 32.6 +/- 13.3 and 30.9 +/- 9.8% for cromakalim- (n = 6) and celikalim-treated (n = 5) animals, respectively. Intravenous diltiazem decreased myocardial infarct size to 16.3 +/- 7.3% (n = 5) of area at risk (p = NS vs. vehicle). The anatomic area at risk was similar in all three treatment groups, and no significant differences in rate-pressure product were observed. Results of this study suggest that K-channel-activating drugs such as cromakalim and celikalim may not be effective agents in the acute therapeutic management of myocardial ischemic injury.
Hearing preservation in acoustic neuroma surgery: a continuing study.
Hearing preservation in acoustic neuroma surgery is possible in a limited number of cases. Although there have been many articles published about hearing preservation, there have been few studies of long-term hearing results, nor is it known if there is an increased rate of tumor recurrence when hearing preservation is attempted. Twenty-two patients who underwent a hearing preservation procedure via the retrosigmoid approach were selected from 80 consecutive patients with cerebellopontine angle tumors operated on from February 1984 to November 1987. Useful hearing was retained in 11 cases as reported in a previously published study. Seven patients continue to have useful hearing after 3 to 5 years; 3 have shown a gradual but slight decline. There has been no tumor recurrence in these patients, but 2 patients, operated on early in the series and who had lost hearing, had recurrent tumor.
Antithrombotic activity of the phosphodiesterase III inhibitor pelrinone in a canine model of coronary artery thrombosis: enhancement of efficacy with concurrent alpha 2-adrenergic antagonism.
The purpose of this study was to determine if idazoxan, an alpha 2-adrenergic antagonist, could enhance the antithrombotic activity of pelrinone, a PDE III inhibitor, in a canine model of coronary thrombosis that uses electrical current to injure the coronary endothelium. Thrombus mass in vehicle-treated animals was 37.9 +/- 8 mg. Pelrinone, 0.625 and 2.5 mg/kg decreased thrombus size by 46 and 21%, respectively, while idazoxan, 0.75 mg/kg decreased thrombus mass by 43%. When this dose of idazoxan was combined with pelrinone, 0.625 and 2.5 mg/kg, thrombus mass was decreased by 71 and 91%, respectively. Antithrombotic efficacy correlated with the ability of these treatments to inhibit epinephrine-sensitized, collagen-induced platelet aggregation. Sixty minutes following drug administration, idazoxan, 0.50 mg/kg inhibited aggregation by 50%, while pelrinone, 0.625 and 2.5 mg/kg inhibited aggregation by 55 and 68%, respectively. Combined administration of idazoxan with pelrinone, 0.625 and 2.5 mg/kg resulted in 80 and 95% inhibition of aggregation, respectively. Similar trends in inhibiting platelet aggregation to epinephrine-sensitized ADP and arachidonic acid were also observed. Experimental treatments did not affect hematocrit or circulating platelet count, although pelrinone was observed to prolong prothrombin time slightly. To examine the effect of drug-induced increases in coronary blood flow on thrombus formation, the potassium channel activator drug cromakalim was studied at a dose (0.1 mg/kg) that increased coronary blood flow by 25-35 ml/min above baseline in sham control animals. Animals treated with cromakalim showed a shorter time to coronary occlusion (103 +/- 11 min) vs. vehicle (173 +/- 24 min) and developed larger thrombi (53.7 +/- 19 mg). These results demonstrate that coronary vasodilation does not contribute to antithrombotic activity in this model. Results from the study also show that alpha-adrenergic inhibition of platelet function can potentiate phosphodiesterase inhibitor antiaggregatory and antithrombotic activity.
Effect of cold preservation on lymphocyte adherence in the perfused rat liver.
A study was designed to determine if cold preservation induces an increase in lymphocyte adherence to liver sinusoids on reperfusion. Rat livers were stored at 1 degree C in University of Wisconsin solution for 45 min, 8 hr, or 30 hr, and then reperfused for 90 min at 37 degrees C in an isolated perfused rat liver apparatus. Just prior to reperfusion, isogeneic rat lymphocytes prepared on a Ficoll-Paque gradient were added to the perfusate. In some studies lymphocytes were labeled with a fluorescent lipophilic membrane marker. There was no change in the number of circulating lymphocytes in an anhepatic circuit. When livers were present in the circuit, lymphocytes were lost from the perfusate into the liver in all studies, with the most rapid decrease occurring within 10 min of reperfusion. The length of preservation had a marked and statistically significant effect on the rate of disappearance of lymphocytes from the perfusate. Reduction by 50% of the number of lymphocytes infused did not affect the results when expressed as percent lymphocytes remaining in perfusate. To exclude the possibility that the loss of lymphocytes into the liver was due to a damaged subpopulation of lymphocytes, two livers stored 3 for 45 min were put into the circuit in sequence. The percent reduction in cells due to exposure to a second liver was not significantly different from that observed when cells were exposed only to a single liver. Histological studies showed fluorescence-labeled lymphocytes adherent in sinusoids, and the number of labeled cells was directly related to the length of preservation. Cold preservation induces an increase in lymphocyte adherence in the reperfused liver, which might be important in graft malfunction and rejection.