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Biomedical subjects

C K Brown

Publications and source records attributed to C K Brown.

At least 55 records · Page 3Linked to original sources
PubMed1994

Strenuous exercise decreases motility and cross-sectional area of human gastric antrum. A study using ultrasound.

Gastric emptying in humans is delayed with strenuous exercise. We used ultrasound imaging in six healthy volunteers to determine whether changes in motility and configuration of the gastric outlet contribute to this delay. After fasting, all individuals ingested chicken broth and garbanzo beans. With subjects sitting upright, transverse and longitudinal real-time views of the gastric antrum were recorded on video tape. In the exercise studies, subjects pedaled an ergometer for 10 min to attain a heart rate of 85% predicted maximum. On a different day, all subjects had an identical study without exercise. The order of performance of exercise and no-exercise studies was randomized. After exercise, contraction frequencies and antral areas were significantly reduced compared to the studies without exercise. In addition, after exercise there was closure of the pylorus and tubular narrowing of the gastric antrum. Closure of the pylorus and decreased gastric antral area and motility may be important in explaining the decrease in gastric emptying that occurs with strenuous exercise.

Adult↗
PubMed1993

The association of HLA-B8, B51, DR2, and multiple sclerosis in pars planitis.

PURPOSE: To establish a human leukocyte antigen (HLA) association in a homogeneous population of patients with pars planitis. METHODS: A strict set of inclusion parameters was established for the diagnosis of pars planitis. Forty patients with pars planitis who met these criteria underwent HLA analysis of class I and II phenotypes. RESULTS: HLA-B8 was present in 15 (37.5%) of 40 patients versus 85 (19.7%) of 431 controls (relative risk, 2.44; P = 0.011). HLA-B51 was present in 9 (22.5%) of 40 patients versus 51 (11.8%) of 431 controls (relative risk, 2.16; P = 0.049). HLA-DR2 was present in 27 (67.5%) of 40 patients versus 121 (28.0%) of 431 controls (relative risk, 5.32; P < 0.0001). HLA-DR2 has been associated with multiple sclerosis (MS). Exclusion of five patients with pars planitis in whom MS subsequently developed did not change the significance of these findings. CONCLUSIONS: The strongest association of pars planitis with HLA-DR2 and the temporal development of MS in some patients with pars planitis further supports an association between pars planitis and MS.

Case-Control Studies↗
PubMed1993

Long-term speech results of cleft palate patients with primary palatoplasty.

This investigation examined the influence of cleft type, type of surgery, age at surgery, and gender on speech proficiency of 204 patients with cleft palate who required only primary palatoplasty. Speech measures were obtained for each subject from at least three annual examinations between the ages of 4 and 16 years. Neither age at surgery nor type of surgery were discriminating factors. The less extensive cleft type, i.e., soft palate only, was associated with greater rates of change in the performance variables than were the other three cleft types. Females showed greater rate changes than males.

Adolescent↗
PubMed1992

Marine trauma, envenomations, and intoxications.

When humans encounter marine creatures a variety of maladies may occur, ranging from dermatitis to life-threatening trauma, allergy, envenomations, or intoxications. The emergency physician should be prepared to recognize quickly and address appropriately the potential life threats, which are primarily neurologic, respiratory, and cardiovascular. A high degree of suspicion for these illnesses is needed. Intoxications may be especially confusing. Although most of the syndromes are self-limited and treatment supportive, time is of the essence if neuromuscular paralysis, hypotension, or respiratory compromise is present. Much folklore exists regarding detection and prevention of these entities and should be regarded as such. The last several decades have seen a marked increase in our knowledge base regarding these fascinating envenomations and intoxications. Research in the next several decades probably will produce a variety of diagnostic and therapeutic tools, which will further our understanding of, and ability to specifically manage, these syndromes.

Animals↗
PubMed1991

The occupational risk of cytomegalovirus infection among day-care providers.

We prospectively studied day-care providers at six day-care centers in south-eastern Iowa to determine their occupational risk for primary cytomegalovirus infection and to define epidemiologic risk factors. Ninety-six (38%) of 252 day-care providers were seropositive for cytomegalovirus by latex agglutination at entry into the study. Among 82 seronegative providers available for follow-up, seven seroconversions occurred at only two of the six participating centers, yielding an annualized seroconversion rate of 7.9%. Median time to seroconversion among these providers was 13 months. Using Kaplan-Meier estimates of risk, we determined that the overall risk of seroconversion among providers at various centers ranged from 0% to 22% by 12 months and from 0% to 40% by 16 months. Risk of cytomegalovirus acquisition by providers was independent of race, age, education, the presence of a child at home, or caring for children younger than 2 or 3 years in the day-care center. However, the risk of seroconversion among day-care providers appeared to parallel rates of cytomegalovirus excretion and acquisition among children at each center.

Adult↗
PubMed1991

The nature of naturally occurring mutations in the hemagglutinin gene of vaccinia virus and the sequence of immediately adjacent genes.

The expression of the vaccinia IHD-J hemagglutinin (HA) gene is regulated by two promoters, an early/late and a second distinct late promoter. The first promoter results in transcripts that begin early and are synthesized throughout the infection. All transcripts from this promoter initiate at the same 5' site. A second promoter is only active late in infection and initiates transcription some distance upstream of the first promoter. We have previously shown that the transcriptional start site controlled by this second, "late only" promoter lies within the coding sequence of an upstream reading frame (p16-ORF), whereas the termination of early transcription of the HA gene utilizes a transcription termination signal (TTTTTNT) located just beyond the coding region of an immediately downstream reading frame (p17-ORF). In order to assist our understanding of HA gene expression, we report here the sequence of these two ORFs adjacent to the HA gene. The HA-ORF itself consists of 945 bp, whereas the upstream p16-ORF consists of 429 bp and the downstream p17-ORF of 453 bp, sufficient to encode polypeptides of 16 and 17 kD, respectively. While many strains of vaccinia are HA+, rabbitpox virus and the variant of vaccinia IHD-J, designated IHD-W, are HA-. We report and compare here the HA gene sequences of wild-type rabbit poxvirus, two spontaneous HA+ revertants of rabbit poxvirus, and the HA- vaccinia strain IHD-W to that of the previously sequenced (1) prototype HA+ IHD-J strain of vaccinia. All differences were found to occur within the HA open reading frame.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Intraosseous transfusion in an anesthetized swine model using 51Cr-labeled autologous red blood cells.

Peripheral venous access can often be difficult to obtain in infants and young children. Landmark articles in the 1940s showed that the intraosseous (IO) route was a viable one for resuscitation. While anecdotal reports and clinical experience suggest that blood products can be transfused via the IO route, it has not been specifically studied nor documented. We performed a prospective study to document the feasibility of red blood cell transfusion via the IO space. We studied the rapid infusion of 51Cr-labeled red blood cells via the IO space through an 18-gauge IO needle in three normovolemic immature swine. Serial central venous samples were removed at 30 seconds and at 1, 5, 15, 30, and 60 minutes and analyzed for evidence of radiolabeling. Our results revealed rapid delivery of radiolabeled red blood cells into the central circulation with no evidence of early heomolysis. Highest counts were seen in samples taken at 30 seconds to 1 minute. We conclude that the IO route is a viable means for blood transfusion in a nonhemorrhagic model.

Animals↗
PubMed1991

Molecular characterization of the vaccinia virus hemagglutinin gene.

The vaccinia virus hemagglutinin (HA) is a glycoprotein found on the plasma membrane of infected cells and the envelope of extracellular virus. Two forms of HA (85 and 68 kDa) are detected by immunoblot analysis. Although hemagglutination activity is only readily detectable late in infection, the 85-kDa HA appears early and accumulates throughout infection, whereas the 68-kDa form appears only late in the cycle. Production of the 68-kDa HA but not the 85-kDa HA was inhibited by either cytosine arabinoside or rifampin. Analysis of HA gene expression reveals a complex pattern of expression. The HA gene is transcribed early to yield a 1.65-kb dicistronic early transcript, consisting of the 945-bp HA open reading frame (ORF) fused to a 453-bp downstream ORF. Transcription from this site initiates 7 bases upstream of the AUG initiating codon of the HA ORF. Due to the discrepancy between the calculated size of the HA protein (33 kDa) and that reported for the unglycosylated HA protein derived from in vitro translation (58 kDa), we placed an early transcription termination signal (TTTTTAT) directly downstream of the 945-bp HA ORF. This led to a reduction in size of the early HA mRNA to 1.2 kb, as expected, but had no effect on the formation of either the 85- or 68-kDa protein. Transcripts originating from the early promoter are found throughout the infection cycle. However, after DNA replication, transcription from a second, late promoter ensues. The transcriptional start site of the late promoter is within a consensus TAAATG sequence located 135 bases upstream of the transcriptional start site of the first promoter. The late transcriptional start site is also found within an upstream ORF.

Amino Acid Sequence↗
PubMed1990

Critical evaluation of the cocaine test in the diagnosis of Horner's syndrome.

We evaluated the effectiveness of the cocaine test for diagnosing Horner's syndrome. The test was administered to 119 patients with a diagnosis of Horner's syndrome and to 50 normal subjects. We compared the cocaine-induced anisocoria in the two groups by measuring photographs of the pupils. We found the cocaine test to be highly effective in separating normal subjects from patients with Horner's syndrome. The chances of having Horner's syndrome increased with the amount of cocaine-induced anisocoria. Through the use of logistic regression analysis, we determined the odds ratio of having Horner's syndrome compared with not having it for each 0.1-mm increment of anisocoria measured after cocaine administration. A postcocaine anisocoria value of 0.8 mm gave a mean odds ratio of approximately 1050:1 that Horner's syndrome was present (lower 95% confidence limit = 37:1). We found that simply measuring the postcocaine anisocoria provided a better prediction of Horner's syndrome than taking the trouble to calculate the net change in anisocoria. Odds ratios should help the clinician decide if the result of a cocaine test is indicative of Horner's syndrome.

Adult↗
PubMed1990

Velar-pharyngeal status in cleft palate patients with expected adenoidal involution.

This study was designed to provide information about whether cleft palate patients with hypertrophied adenoids maintain velar-pharyngeal contact during the time of expected adenoidal atrophy. Thirty-nine subjects were selected from a large longitudinal study on the basis of availability of lateral still x-ray films taken in series from 5 to 16 years of age. Ratings of velar-pharyngeal contact and ratings of adenoid size were obtained from the films. The obtained data indicated the expected decrease in adenoid size but also, for the group, maintenance of velar-pharyngeal contact. However, three of the 39 subjects were judged to show loss of such contact during the period of study, and an additional four had surgery for velopharyngeal incompetence after the completion of the study. All seven appeared to show significant deterioration of velopharyngeal status in middle or late adolescence. Implications of these findings are discussed.

Adenoids↗
PubMed1990

Use of metoclopramide, domperidone, and cisapride in the management of diabetic gastroparesis.

The pathophysiology, diagnosis, and treatment of diabetic gastroparesis are reviewed, and the mechanisms of action, pharmacokinetics, clinical efficacy, adverse effects, and dosage of metoclopramide, domperidone, and cisapride are described. Diabetic gastroparesis is a state of delayed gastric emptying that reportedly affects 20-30% of diabetic patients. Symptoms include nausea, early satiety, postprandial bloating and fullness, and vomiting. Diabetic gastroparesis has been managed most successfully with drugs that stimulate gastric emptying. Of the three agents studied--metoclopramide, domperidone, and cisapride--only metoclopramide is commercially available in the United States. The clinical efficacy of metoclopramide, domperidone, and cisapride has been well documented in several placebo-controlled trials. Metoclopramide effectively decreases mean gastric emptying time, although tolerance to this stimulation of gastric emptying may develop with long-term therapy. However, symptomatic relief persists with long-term therapy because of metoclopramide's antiemetic properties. Domperidone, which has also been shown to stimulate gastric motility and to possess antiemetic properties, improves symptoms in patients suffering from diabetic gastroparesis. Cisapride appears to have continued beneficial effects on gastric motility with long-term therapy. All three agents have favorable adverse-effect profiles. Although metoclopramide is currently the first-line agent for the management of gastroparesis, domperidone and cisapride both possess properties that may make them useful alternatives in patients who are unresponsive to or cannot tolerate metoclopramide therapy.

Cisapride↗
PubMed1989

Motility changes in opossum esophagus from experimental esophagitis.

We assessed how acute inflammation affects the contractile activity of the esophageal body. Two models of esophagitis were used: nine opossums had an esophageal perfusion of 100 meq hydrochloric acid for 2 hr and were studied at 24 hr. Ten had the perfusion for 4 h and their esophagitis were studied in vitro after 72 hr. Comparisons were made in all instances to animals who had esophageal saline perfusion for identical periods. All acid-perfused animals developed gross and histologic evidence of mucosal inflammation; in three animals, inflammatory changes extended into the submucosa and the muscularis propria. Manometric recordings in the acid-perfused animals revealed esophageal shortening, frequent failure of primary peristalsis and frequent occurrence of spontaneous contractions. Recordings of isometric tension of muscle in vitro revealed spontaneous contractions in strips from the mucosa and from the circular and from the longitudinal muscle. The amplitude of contractions in response to electrical stimulation was decreased, but the duration of contractions was increased largely because of a prolonged recovery phase. These changes in mechanical response occurred with stimulus parameters directed at both the muscle and the intrinsic nerves. We conclude that esophageal inflammation can lead to an increased irritability and decreased stimulus response of the smooth muscle of the esophagus even where it is not directly involved in an inflammatory response. These changes correspond to the functional abnormalities of the esophagus seen in patients with reflux esophagitis.

Animals↗
PubMed1989

The incidence and significance of hemostatic abnormalities in patients with head injuries.

Abnormal coagulation and fibrinolysis is a frequent complication in patients with head injury. This complication can be severe enough to lead to hemorrhage or thrombosis. A study was undertaken to determine if the hemostatic abnormalities are reliable indicators of outcome. Hemostasis in 269 patients with head injuries alone was screened using platelet count (PC), prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin clotting time (TCT), fibrinogen assay (FIB), level of fibrin-fibrinogen degradation products (FDP), and disseminated intravascular coagulation (DIC) score in the first 24 hours after injury. Test results were compared with the outcome (discharged or dead) in the entire group and in subgroups divided on the basis of the severity of injury as determined by the Glasgow coma score (GCS). Increased consumptive coagulopathy at admission, as reflected in the DIC score, predicts the outcome of head-injured patients with a high degree of accuracy. The degree of increase of the initial FDP level and prolongation of TCT also correlated positively with the outcome. Prolongation of the APTT correlated strongly with unfavorable outcome in a large group of patients, and in a small group, markedly accelerated APTT also predicted death. Stepwise logistic regression analysis demonstrated that GCS, FDP level, and DIC score predicted outcome. Other tests did not provide additional predictive value. Abnormal hemostasis frequently complicates the course of patients with head injuries. This study demonstrates that hemostasis tests are predictors of outcome in these patients.

Adolescent↗
PubMed1988

Meckel's diverticulum.

Meckel's diverticulum is a cause of significant morbidity and mortality. Often this is related to the delay in diagnosis. Based on a US population of 200 million people and a 2% incidence, there are 4 million Meckel's diverticula present waiting to cause symptoms. Considering that most Meckel's diverticula are asymptomatic and that many authors have described the condition as a great mimic, the diagnosis is often quite elusive. Therefore, a high index of suspicion is needed to diagnose Meckel's diverticulum correctly and expeditiously as the source of disease in the patient with an often unclear abdominal presentation. The difficulty with diagnosis should be lessened if one considers that Meckel's diverticulum presents largely in the male and younger age groups with the three major symptom complexes of bowel obstruction, gastrointestinal bleeding, and inflammation. Use of 99mTc pertechnetate scintigraphy appears to be the diagnostic study of choice if Meckel's diverticulum is suspected and the patient is clinically stable. When one considers the potential for bad outcome if Meckel's diverticulum is missed in the setting of possible obstruction or hemorrhage (i.e., bowel infarction or exsanguination), a high index of suspicion and diagnostic aggressiveness is warranted. Lastly, if one thought is to be left behind, it should be: "Meckel's is a great mimic that must be considered in all cases of intra-abdominal disease in which the cause is not readily apparent."

Adolescent↗
PubMed1988

Interactions in the labial musculature during speech.

Interactions in electromyographic activity of the upper and lower lips during speech were studied by manipulating the magnitude of bursts of activity related to bilabial closure. Four pairs of electrodes were placed in the labial musculature in each of four normal-speaking young adults. Manipulation of muscle activity usually resulted in positively correlated changes in activity recorded from the other three electrode pairs. Similar effects were found when lower lip muscle activity was manipulated and when upper lip muscle activity was manipulated, suggesting there is no asymmetry in the interactions between lips. Measurements of lower lip closing movement often correlated with the modulated muscle activity, suggesting that the size of lip opening was varied to accommodate different closing forces. The flexibility of a system producing positive correlations in the activity of different labial regions is discussed and contrasted with the suggestions that there are complementary variations, producing negative correlations, in the activity of different labial muscles during speech.

Adult↗