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Biomedical subjects

H Crow

Publications and source records attributed to H Crow.

11 recordsLinked to original sources
PubMed2000

Gallbladder ejection fraction: correlation of scintigraphic and ultrasonographic techniques.

PURPOSE: The assessment of gallbladder function and ejection fraction using sincalide-enhanced biliary scintigraphy is a useful way to evaluate patients with recurrent right upper quadrant pain but no gallstones. MATERIALS AND METHODS: We wanted to determine whether gallbladder contraction measured by ultrasonography could be used in place of biliary scintigraphy. Biliary scans with an infusion of sincalide and concurrent ultrasonography were performed in 17 patients with histories of recurrent abdominal pain and no evidence of gallstones by ultrasound. RESULTS: Gallbladder ejection fractions calculated by ultrasound and scintigraphy using standard techniques showed only a weak correlation. The poor performance of ultrasound appears to arise because the variable shape of the gallbladder invalidates the calculation of its volume by the formula for a prolate spheroid. When gallbladders that were ellipsoidal were subselected, correlation was improved. The level of training of the sonologist did not have a significant effect on the results. CONCLUSION: Gallbladder ejection fraction calculated by ultrasonography cannot be used routinely as a substitute for biliary scintigraphy.

Abdominal Pain↗
PubMed1998

Predictive factors for functional recovery after free tissue transfer oromandibular reconstruction.

BACKGROUND: Recovery of upper aerodigestive tract function after reconstruction of segmental oromandiblectomy defects is frequently incomplete. The purpose of this study was to quantitate postreconstruction function and define variables that predict functional outcome in this population. METHODS: A prospective study of 21 patients who underwent microvascular free tissue transfer reconstruction of segmental oromandibular defects was performed. Measures of swallowing, speech, bite, and oral intake were performed preoperatively and at 1, 3, 6, and 12 months postoperatively or until plateau. Preoperative versus maximal postoperative measures were compared and correlated with nine potentially predictive variables. Univariate and multivariate analyses were performed to determine the most significant predictive factors. RESULTS: Baseline function in the study population was abnormal. Postoperative bite force improved, but swallowing, speech, and oral intake were worse than preoperative. Significant (univariate) predictors of outcome included diagnosis of cancer, tongue resection, pharynx resection, and flap skin paddle area. Only tongue resection remained significant in multivariate analysis. CONCLUSIONS: Increasing need for oropharyngeal lining replacement, especially after tongue resection, is the most important predictor of functional outcome in reconstruction of segmental mandible defects.

Adult↗
PubMed1998

Examiner expectancy effects in the measurement of pressure pain thresholds.

The ascending Method of Limits, used for the determination of pressure pain thresholds (PPT), is not a psychophysically robust method. The present study sought to determine if the examiner's expectancy, based on whether the measurement site was clinically 'painful' or 'non-painful', would bias the obtained PPT values. Twenty-eight patients with facial or temporal area pain served as subjects, and in each subject, a pain site and a control site were identified and marked. According to a randomization schedule, the pain and control sites were correctly marked in half of the subjects and were mis-labeled in the other half, thereby controlling the examiner's knowledge of a site and thus the examiner's expectancy of what the PPT should be. Two examiners, shown to be reliable with each other in both pre-clinical and post-clinical reliability studies, were blind to the true purpose of the study and to the marking procedures. Each examiner made one PPT measurement at each marked site in a counterbalanced measurement order. Manipulating the examiner's prior knowledge of the measurement site's characteristics significantly lowered the obtained PPT values for control sites but did not significantly alter the PPT at the clinically painful sites. Nevertheless, the pain sites still had significantly lower PPTs than did control sites. We conclude that: (i) PPTs at pain sites are robust to a major source of measurement bias associated with the ascending Method of Limits; (ii) measurement order and knowledge of measurement site characteristics can influence obtained PPT; and (iii) the common protocol in which the examiner monitors the amount of pressure during PPT measurement in order to control the force application rate may serve as a mechanism that can bias the obtained values.

Female↗
PubMed1997

A comparison of clomiphene citrate and human menopausal gonadotropin for use in conjunction with intrauterine insemination.

OBJECTIVE: To compare the outcome of superovulation using clomiphene citrate (CC) versus hMG in conjunction with IUI. DESIGN: Sequentially assigned, observational study. Couples initially were assigned to receive either CC or hMG for three cycles. SETTING: The Clinical Outpatient Department of the Dartmouth-Hitchcock Medical Center. PATIENT(S): Eighty-three infertile couples. INTERVENTION(S): IUI with hMG use. MAIN OUTCOME MEASURE(S): Conception rate, term pregnancy rate (PR), and pregnancy complications, such as spontaneous miscarriage and multiple gestation. RESULT(S): Of 83 couples who underwent at least one treatment cycle, 29 (35%) conceived during the study period. The relative rate of conception for hMG versus CC was 2.08 (95% confidence interval [CI], 0.93 to 4.68). The relative term PR was 2.10 (95% CI, 0.77 to 5.73) for hMG versus CC. There was no difference in the miscarriage rate for hMG versus CC. CONCLUSION(S): Both the conception rate and the term PR were higher using hMG, compared with CC, in combination with IUI, and showed a trend toward statistical significance.

Adult↗
PubMed1994

A correlational study of carbohydrate-deficient transferrin values and alcohol consumption among Hispanic college students.

One hundred and forty-eight U.S. college students from a small southwestern university were asked to provide or complete the following: the Michigan Alcoholism Screening Test (MAST), a structured alcohol-use interview, and a 10-ml blood sample to be assayed for carbohydrate-deficient transferrin (CDT) levels and gamma-glutamyl-transpeptidase (GGTP) activity. Using the data obtained in the interview, only 2 females and 5 males were identified as heavy drinkers. Conclusions regarding the efficacy of the biochemical markers are therefore limited. It was found that CDT levels were significantly and positively correlated with various measures of alcohol consumption among males. There was no similar association between CDT, or GGTP, and alcohol consumption within the female sample.

Adolescent↗
PubMed1993

Role of electronic devices in diagnosis of temporomandibular disorders.

The role of electronic devices in the diagnosis of TMD raises the critical question of whether the clinician can gain diagnostically relevant information from them. This is of serious concern in view of the sparse, unreplicated and invalidated scientific evidence linking the use of such devices to TMD diagnosis and subsequent therapy. Until such time as scientific studies, using blinded evaluations to compare TMD patients and controls, demonstrate acceptable levels of reliability, validity, sensitivity and specificity, as well as positive and negative predictive values, the use of such devices will continue to have questionable diagnostic validity and, therefore, will continue to be considered experimental. Thus, clinicians should carefully consider the diagnostic and therapeutic consequences of using electronic devices prior to adding them to their dental armamentarium.

Electromyography↗
PubMed1987

Isolation and partial amino acid sequence of three subunit species of porcine spleen ferritin: evidence of multiple H subunits.

A partial amino acid sequence for three different subunits of the iron storage protein, ferritin, has been determined. Ferritin (Mr approximately 480,000) was isolated from porcine spleen and dissociated into its component subunits (Mr approximately 20,000). The subunits, in turn, were separated into three fractions by reversed-phase HPLC. The fractions appeared to be of equal size by sedimentation velocity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and size-exclusion chromatography in 6 M guanidinium chloride. All three fractions were shown to be monomeric and to have no covalently attached carbohydrate (J. F. Collawn et al. (1984) Arch. Biochem. Biophys. 233, 260-266). Determination of the amino acid sequence of the C-terminal 70-80 residues from each of the fractions demonstrated three different sequences. Comparison with human liver H and L subunit sequences indicates that two of the porcine ferritin subunits are H-type subunits and one is an L-type subunit. Application of the Chou-Fasman algorithm on the three partial sequences suggests that these respective regions from each of the three subunits would probably adopt the same conformation.

Amino Acid Sequence↗
PubMed1984

Cystatin. Amino acid sequence and possible secondary structure.

The amino acid sequence of cystatin, the protein from chicken egg-white that is a tight-binding inhibitor of many cysteine proteinases, is reported. Cystatin is composed of 116 amino acid residues, and the Mr is calculated to be 13 143. No striking similarity to any other known sequence has been detected. The results of computer analysis of the sequence and c.d. spectrometry indicate that the secondary structure includes relatively little alpha-helix (about 20%) and that the remainder is mainly beta-structure.

Amino Acid Sequence↗
PubMed1983

Dogfish insulin. Primary structure, conformation and biological properties of an elasmobranchial insulin.

Insulin from an elasmobranch, the spiny dogfish (Squalus acanthias) has been purified to near homogeneity by means of acid-ethanol extraction and salt precipitation. The amino acid sequences of the performic-acid-oxidised A and B chains have been determined and exhibit some unusual features. The A chain contains a total of 22 amino acids; only the insulin from coypu (a member of the Rodentia suborder, Hystricomorpha), has previously been reported to contain an extension past the A21 asparagine. The B10 histidine, which is involved in the formation of the insulin hexamers in higher vertebrates through the co-ordination of zinc, is present in this elasmobranch insulin. Several substitutions relative to bovine insulin occur in the proposed receptor binding region (A5Gln leads to His, B21Glu leads to Pro, B22Arg leads to Lys, B25Phe leads to Tyr). In spite of these substitutions, the maximal response in the rat epididymal fat cell assay is the same for bovine and dogfish insulins; the concentration required to produce the half-maximal response is, however, approximately threefold greater for dogfish insulin than that of bovine insulin. The use of interactive computer graphics model-building predicts that the dogfish insulin can attain a three-dimensional structure very similar to that of bovine insulin; circular dichroic spectra are presented which support the model-building studies.

Adipose Tissue↗