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Biomedical subjects

D Olsen

Publications and source records attributed to D Olsen.

At least 37 records · Page 2Linked to original sources
PubMed1996

A descriptive survey of management and operations at selected sports medicine centers in the United States.

No uniform guidelines for operations or accreditation standards for sports medicine center were available and, at the time of this study, little information on the management and operation of sports medicine centers was available in the literature. The purpose of the study was to determine the management structure and function of selected sports medicine centers in the United States. Questionnaires were mailed to 200 randomly selected centers throughout the United State from a directory of sports medicine centers published in Physician and Sportsmedicine (1992) to gather descriptive information on eight areas, including 1) general background, 2) staffing, 3) services, facilities, and equipment, 4) billing, collections, and revenue, 5) clientele, caseloads, and referrals, 6) ownership and financing, 7) school and club outreach contracts, and 8) marketing strategies and future trends. A total of 71 surveys (35.5%) were returned in the allotted time frame. Data were analyzed using ranges, means, medians, modes, and percentages. Results yielded several conclusions about sports medicine centers. Nearly all (93%) of the centers employed physical therapists; physical therapists were clinical directors at 70.2% of centers; orthopaedists were most often medical directors; rehabilitation was the most frequently offered service (93%); physical therapy produced the highest revenue; sports injuries accounted for a mean 34.5% of patients, who were mostly recreational or high school athletes between 13-60 years of age; primary shareholders were most often physical therapists or physicians; most were involved in outreach services for schools; marketing strategies primarily involved communication with referral sources; and managed care was identified most frequently as a trend affecting the future of sports medicine centers. Findings identified common aspects of sports medicine centers and may assist in establishing guidelines for operations or accreditation of sports medicine centers.

Health Facilities↗
PubMed1996

Using hybrid magnetic bearings to completely suspend the impeller of a ventricular assist device.

Clinically available blood pumps and those under development suffer from poor mechanical reliability and poor biocompatibility related to anatomic fit, hemolysis, and thrombosis. To alleviate these problems concurrently in a long-term device is a substantial challenge. Based on testing the performance of a prototype, and on our judgment of desired characteristics, we have configured an innovative ventricular assist device, the CFVAD4, for long-term use. The design process and its outcome, the CFVAD4 system configuration, is described. To provide unprecedented reliability and biocompatibility, magnetic bearings completely suspend the rotating pump impeller. The CFVAD4 uses a combination of passive (permanent) and active (electric) magnetic bearings, a mixed flow impeller, and a slotless 3-phase brushless DC motor. These components are shaped, oriented, and integrated to provide a compact, implantable, pancake-shaped unit for placement in the left upper abdominal quadrant of adult humans.

Biocompatible Materials↗
PubMed1995

Cognitive and motivational determinants of academic achievement and behaviour in third and fourth grade disadvantaged children.

While most studies on the determinants of learning deal with either cognition or motivation, there is a growing awareness that both should be considered. Our purpose was to examine the relative roles of cognitive and motivational factors for the scholastic achievement and behaviour of disadvantaged children. Cognition was conceptualised in terms of the psychosemantic theory that assesses cognitive processes by characteristics of the individual's meaning assignment (Kreitler & Kreitler, 1987a). Motivation was conceptualised in terms of the cognitive orientation (CO) theory which assumes that cognitive contents guide behaviour (Kreitler & Kreitler, 1982). Participants were 57 third and fourth graders of both genders, recommended for a remedial summer programme. They were administered the Meaning Test assessing cognitive abilities; the CO Questionnaire of Motivation for Learning assessing the disposition to learn; and the Metropolitan Achievement Test and the IOWA tests assessing verbal, mathematical and working skills. Teachers completed the Teacher-Child Rating Scale assessing six scholastic behaviours. Regression analyses showed that all dependent variables were predicted by the cognitive and motivational variables, better by specific than global predictors. Cognitive variables contributed more to the predictions, especially of academic achievements, and more in the case of verbal than mathematical abilities. In girls, motivational factors played a larger role than cognitive factors, absolutely and relative to boys. Implications for promoting scholastic achievements are discussed.

Achievement↗
PubMed1994

MRI of a waterflood on a reservoir chalk sample.

CSI of a waterflood experiment on a chalk sample from a North Sea hydrocarbon field has been performed. The method works well, giving separate maps of water and oil distributions. Difference images yield detailed information about fluid movements.

Calcium Carbonate↗
PubMed1993

A review of the results of laparoscopic versus open appendectomy.

Proponents of laparoscopic appendectomy emphasize the advantages of laparoscopic operation--decreased hospitalization, paralytic ileus, postoperative pain and wound complications, including infection. This study compared open laparoscopic appendectomy with laparoscopic appendectomy. To compare the two techniques, patients undergoing laparoscopic appendectomy at four hospitals were compared with patients undergoing open appendectomy during a six month period. Excluded were incidental appendectomies and patients with perforated appendicitis. An equal number of pediatric patients undergoing laparoscopic and open procedures were included in the analysis to avoid bias, because most of the laparoscopic appendectomies were performed in the adult patient population (age of more than 16 years). A University Medical Center, a Veterans Administration and two community hospitals were the settings. Patients undergoing laparoscopic appendectomy (n = 54) had an average age of 25.7 +/- 1.5 (range of six to 59 years). These patients were compared with 121 patients undergoing open appendectomy whose average age was 23.7 +/- 1.8 (range of three to 83 years). The race and gender distribution were similar in the two groups. Traditional open appendectomy was compared with a group of patients undergoing laparoscopic appendectomy. Variables evaluated were operating room time, number of patients who reported nausea, days until patient tolerated a regular diet, days of hospitalization, postoperative pain medication and wound infection rate. Results are expressed as the mean plus or minus standard error of the mean. Analysis of variance was used to compute continuous variables and Fischer's exact test was used for discrete variables. The laparoscopic approach was attempted in 61 patients and completed in 54 patients. Open appendectomy was performed upon 121 patients. Nineteen patients (18 who underwent open operation and one patient who underwent laparoscopic operation) were excluded from further analysis because of perforated appendicitis. The open procedure took less time (p < 0.05). However, there were more wound infections than in the laparoscopic group (seven of 103 versus zero of 53; p = 0.09). Patients with acute appendicitis recuperated more quickly from the laparoscopic procedure, as evidenced by the time until eating regular diet, period of hospitalization, incidence of nausea and pain medications on postoperative day one (p < 0.05). The absence of wound infections after laparoscopic appendectomy can be attributed to the practice of placing the appendix in a sterile bag or into the trocar sleeve before removal from the abdomen. Laparoscopic appendectomy reduces the period of hospitalization, postoperative ileus, nausea and postoperative pain in patients with acute appendicitis.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1992

The effect of desmopressin acetate on postoperative hemorrhage in patients receiving aspirin therapy before coronary artery bypass operations.

It has been suggested that desmopressin acetate has been effective in reducing hemorrhage after coronary artery bypass grafting in patients receiving aspirin before operation. We conducted a prospective, randomized, placebo-controlled, double-blind trial to determine the effectiveness and safety of desmopressin in these patients. Sixty-five patients pretreated with aspirin within 7 days before their scheduled elective coronary artery bypass grafting were randomized to receive desmopressin (0.3 micrograms/kg) or placebo after cessation of bypass and reversal of heparin with protamine. The demographic characteristics and last dose of aspirin were similar in both groups. There was a significant reduction in postoperative blood loss noted between groups for both chest tube blood loss (833 +/- 311 ml for the 1-desamino-8-D-arginine vasopressin [desmopressin] group versus 1176 +/- 674 ml for the placebo group; p = 0.016) and total blood loss (1215 +/- 381 ml for the desmopressin group versus 1637 +/- 761 ml for the placebo group; p = 0.0097). Despite the differences in blood loss between the two groups, the red cell transfusions were not significantly different, but the use of platelets was less in the desmopressin group and almost achieved statistical significance (p = 0.053). Neither was there a difference in the occurrence of thrombotic complications between groups. It appears that desmopressin in this specific subgroup of patients receiving preoperative aspirin is effective as a prophylactic agent for reduction of postsurgical hemorrhage.

Aged↗
PubMed1991

Safe performance of difficult laparoscopic cholecystectomies.

Laparoscopic cholecystectomy has been advocated for the treatment of uncomplicated symptomatic gallstone disease, but has not been widely advocated for the management of more complicated gallbladder disease such as acute cholecystitis, previous surgery, or common duct stones. During the last 9 months, 360 patients underwent laparoscopic removal of their gallbladder. A total of 138 had a complicated presentation, making surgery more difficult. This article discusses the management of these patients with acute cholecystitis, previous surgery, or common duct disease. Using the described techniques, there were no complications or mortality. Laparoscopic management of difficult gallbladder problems is safe and effective.

Acute Disease↗
PubMed1991

Mosaic variegated aneuploidy with microcephaly: a new human mitotic mutant?

We report the case of a 17 year old girl with severe microcephaly and mental retardation, in whom karyotype analysis of PHA-stimulated lymphocytes, cultured skin fibroblasts, direct and cultured bone marrow and EBV-transformed lymphoblasts all showed at least 10% of cells with trisomy, which could be for many different chromosomes. All trisomies except 5, 10, 13, 14 and 17 were observed. Tissue-specific differences in the predominant trisomy occurred. The existence of this mosaic trisomy in four different tissues and in repeated cultures over a three year period suggests that it is due to a genetic abnormality resulting in mitotic instability. This case is compared with six previously reported human cases with a similar phenomenon, including two pairs of siblings. It is unclear whether all cases represent the same condition, since clinical and cytogenetic differences exist among them. The term "mosaic variegated aneuploidy with microcephaly" is suggested as a descriptive term for this syndrome.

Adolescent↗
PubMed1990

Laparoscopic laser cholecystectomy and choledocholithiasis.

The management of common bile duct stones during laparoscopic laser cholecystectomy (LLC) is uncertain. Open common bile duct exploration is the least desirable option since it defeats the purpose of LLC. Endoscopic retrograde cholangiopancreatography (ERCP) with papillotomy has become the procedure of choice since it has a high rate of success and results in minimal morbidity. Intraoperative techniques using balloon catheters and the flexible choledochoscope via the cystic duct may obviate the need for ERCP in selected cases.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1989

Human laminin: cloning and sequence analysis of cDNAs encoding A, B1 and B2 chains, and expression of the corresponding genes in human skin and cultured cells.

A human placental lambdagt11 expression cDNA library was probed for laminin cDNAs by a combination of immunoscreening using polyclonal anti-human laminin antibody, and plaque hybridizations using a mouse laminin A chain cDNA. A total of 36 recombinant clones were isolated and characterized. Northern blot hybridizations with poly(A)+RNA, isolated from cultured human skin fibroblasts, revealed hybridization either to (a) a single 10 kb transcript consistent with A chain; (b) a single 5.7 kb transcript consistent with B1 chain; or (c) polymorphic 5.6 and 8.2 kb transcripts consistent with B2 chain of human laminin. Nucleotide sequencing of representative cDNA clones (approximately 2.5 kb in size) confirmed that these three groups of cDNAs encoded C-terminal sequences of laminin A, B1 and B2 chains, respectively. Deduced amino acid sequences for both B1 and B2 chains contained epidermal growth factor-like sequences and alpha-helical heptad repeats, as found previously for mouse laminin. Partial laminin A chain cDNA encoded 680 amino acid residues characterized by several internal repeats. This portion of the peptide accounted for a large part of the globular domain (fragment 3), the whole length of a second (T2) and portions of a third (T1) globular domain. The human A chain also contained an Arg-Gly-Asp sequence, a potential cell-binding site, which is not found in the same segment of mouse laminin. The newly isolated cDNAs were also utilized to analyze expression of laminin mRNAs by cultured human cells and tissues. The results demonstrated that the laminin A, B1, and B2 chain genes were expressed in an uncoordinate manner in both cultured cells and tissues, with a particularly low level of the A chain mRNA being present.

Amino Acid Sequence↗
PubMed1987

Effect of long-term administration of an analog of growth hormone-releasing factor on the GH response in rats.

The effect of the repeated or continuous administration of an analog of GH releasing factor (GH-RF), D-Tyr-1, D-Ala-2, Nle-27, GH-RF(1-29)-NH2 (DBO-29), on the subsequent response to this peptide was investigated in pentobarbital-anesthetized male rats. A sc administration of this analog induced a greater and more prolonged GH release than doses 10 times larger of GH-RF(1-29). The GH increase after sc injection of 10 micrograms/kg bw of the analog was greater than that induced by iv administration of 2 micrograms/kg bw of GH-RF(1-44). Pretreatment with 10 micrograms/kg bw of the analog did not affect the pituitary response to a strong stimulus (20 micrograms/kg bw) of GH-RF(1-44), 24 h later. Pretreatment with the analog in doses of 10 micrograms/kg bw, sc twice a day, 5 days per week for 4 weeks, significantly diminished the GH release in response to a sc injection of the analog (10 micrograms/kg bw), as compared to vehicle-pretreated controls (P less than 0.01). On the other hand, a continuous sc administration of 0.4 micrograms/h of the analog to intact rats for 7 days did not result in a decrease in GH response to a sc injection of the analog (10 micrograms/kg bw). Since the rats injected repeatedly with the analog for 4 weeks still showed a marked, although somewhat reduced response, analogs of this type may be useful clinically.

Animals↗
PubMed1987

Superactive octapeptide somatostatin analogs containing tryptophan at position 1.

We synthesized a series of octapeptide analogs of somatostatin, containing N-terminal tryptophan or another amino acid followed by the hexapeptide sequences Cys-Phe-D-Trp-Lys-Thr-Cys or Cys-Tyr-D-Trp-Lys-Val-Cys and a C-terminal threoninamide or tryptophanamide. After purification by HPLC, the inhibitory activities of these analogs on the release of growth hormone (somatotropin) in rats were determined in vivo. The eight octapeptides with an N-terminal tryptophan residue were found to have a greater inhibitory effect than somatostatin. The most potent of these analogs, D-Trp-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2, was 94.3 times more active than somatostatin. The other analogs, in order of decreasing potency, were Ac-Trp-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2, D-Trp(For)-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2, D-Trp-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr-NH2, Ac-Trp(For)-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2, Ac-Trp-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr-NH2, D-Trp-Cys-Phe-D-Trp-Lys-Thr-Cys-Trp-NH2, and D-Trp-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2. The growth hormone inhibitory activity of these analogs was from 53.7 to 11.6 times greater than that of somatostatin. The octapeptides containing D- or L-tryptophan at the N-terminus, phenylalanine at position 3, and threonine at position 6 exhibited a greater inhibitory effect on growth hormone release than that of the analogs with tyrosine and valine at positions 3 and 6, respectively. Substitution of D-tryptophan for D-phenylalanine at the N-terminus in the octapeptide containing phenylalanine in the third, threonine in the sixth, and threoninamide in the C-terminal position also increased the growth hormone-release inhibitory activity. Time-course assay showed that D-Trp-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-NH2 (RC-98-I), in a dose of 1 microgram/kg of body weight, inhibited the release of growth hormone for at least 3 hr. In view of their high activity and prolonged duration of action, some of these analogs could be useful clinically.

Animals↗
PubMed1983

Significance of the delta 5 and delta 4 steroidogenic pathways in the hamster preovulatory follicle.

Isolated hamster granulosa cells and theca from preovulatory follicles were incubated in vitro for 2 and 6 h in the absence/or presence of LH and steroid substrates. The purpose of the experiments was to determine, in theca, the relative activities of the delta 5 and delta 4 pathways under controlled conditions, and to compare the ability of granulosa cells and theca to form progesterone from exogenous pregnenolone. The results of the experiments show that the delta 5 pathway in theca predominates before and up to 2 h after LH stimulation. The delayed effect of LH after 2 h is a switch from delta 5 to delta 4 as the major metabolic pathway. Progesterone formation from exogenous pregnenolone is 7 to 10 times greater in unstimulated granulosa cells than in theca. Acute effects of LH lead to increased conversion of exogenous pregnenolone to progesterone in granulosa cells but not theca. LH does, however, acutely stimulate the thecal conversion of DHEA to androstenedione. The longer term effect of LH in both cell types is to increase pregnenolone conversion to progesterone.

Androstenedione↗