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Biomedical subjects

M Dahn

Publications and source records attributed to M Dahn.

11 recordsLinked to original sources
PubMed2000

Formulation and technology aspects of conrolled drug delivery in animals.

In the veterinary field, the development of new routes of administration or new delivery systems capable of controlling the release of drugs are of considerable interest. Because of the large number of food-producing animals and the unique problems associated with the administration of drugs to these animals, the potential markets are huge and will only be fully realized if improvements to old dosage forms lead to practical and effective formulations. This review intends to summarize the state of the art in the field of veterinary controlled and/or prolonged release systems.

Journal Article↗
PubMed1998

Overexpression and purification of cytochrome c oxidase from Rhodobacter sphaeroides.

The aa3-type cytochrome c oxidase of Rhodobacter sphaeroides has been overexpressed up to seven fold over that in wild-type strains by engineering a multicopy plasmid with all the required oxidase genes and by establishing optimum growth conditions. The two operons containing the three structural genes and two assembly genes for cytochrome c oxidase were ligated into a pUC19 vector and reintroduced into several oxidase-deleted R. sphaeroides strains. Under conditions of relatively high pH and maximal aeration, high levels of expression were observed. A smaller expression vector, pBBR1MCS, and a fructose promoter (fruP)5 were found not to enhance cytochrome c oxidase expression in R. sphaeroides. An improved cytochrome c oxidase purification protocol is reported, which combines histidine elution from a nickel affinity column and anion-exchange chromatography, and results in a higher yield and purity than previously obtained.

Chromatography, Affinity↗
PubMed1996

Is DVT prophylaxis overemphasized? A randomized prospective study.

This study was designed to prospectively evaluate a previously published prognostic index for predicting deep venous thrombosis (DVT) in general surgical patients with conventional prophylaxis. Patients undergoing procedures of at least 1 hr duration (abdominal, thoracic, head and neck, inguinal) requiring general or spinal anesthetic were prospectively randomized into the following groups: Group 1, sequential pneumatic compression devices during surgery and 2 days postoperatively; Group 2, subcutaneous heparin (5000 U q 12 hr) starting 1 hr before surgery and for 7 days postop; Group 3, control group. All patients underwent duplex evaluation of bilateral lower extremity deep venous systems preoperatively and on postoperative Days 1, 3, and 30. In addition, a previously developed predictive DVT incidence indicator, the prognostic index (PI), was calculated for each patient. A total of 137 patients were entered into the study with 29 removed for patient/staff reasons. There were no differences in PI among the three groups at the 0.05 level (ANOVA). The distribution of risk factors for DVT including increased age, body size, hemoglobin (Hb), and colorectal procedures were distributed evenly among the groups. Additional factors such as diabetes, COPD, PVD, immobilization, and cancer were also evenly distributed among the groups. The PI predicted a 20% incidence of DVT. For Groups 1 (n = 25), 2 (n = 38), and 3 (n = 45) no DVTs were detected over the 30 days of study. During the study period, 8 DVTs were detected by duplex evaluation in general surgical patients not in the study (1.5%). In conclusion, in a prospective randomized study using sequential pneumatic compression devices, subcutaneous heparin or no prophylaxis in matched general surgical patients at moderate to high risk for thromboembolism, no DVTs occurred for up to 30 days. Furthermore, neither a PI nor other factors associated with DVT accurately predicted the incidence of DVT in this patient population.

Adult↗
PubMed1989

[The radiologic image of the normal equine tarsus].

Normal radiographs of hocks were analyzed for 270 horses (3 views for each hock). They were mainly from young and sound horses. For such animals, the mean number of abnormalities found was 2 to 4.5 for each picture. The mean dimension of certain tarsal bones was measured; geldings had greater bones than mares. An increase of reactions at the origin of the M. interosseus was seen with the age. It was possible to demonstrate that Medichrome films increase the number of discrete abnormalities to be found; this is of particular value for purchase examinations of young horses. The direction of the central beam (angle) is important in order to get symmetrical pictures; a minimal change in this angle can show or hide discrete abnormalities. A description of the normal radiographic anatomy of the equine hock, and its principal variations, is given.

Age Factors↗
PubMed1981

Selective versus standard hyperalimentation. A randomized prospective study.

Fifty consecutive surgical patients were included in a randomized prospective study to determine the relative advantages and disadvantages of two types of nutritional support systems: one, selective hyperalimentation, relies on a balanced substrate formula, while the other, standard hyperalimentation, depends on carbohydrate and protein to satisfy the energy requirements of the patient. The patients who received the balanced substrate formula had significantly fewer complications than those receiving standard hyperalimentation, even though both groups achieved positive energy and nitrogen balance. The enhanced safety of selective hyperalimentation suggests its therapeutic superiority as a basic nutritional support system for a busy surgical service.

Glucose↗
PubMed1981

The therapeutic advantages of a balanced nutritional support system.

Twenty-two critically ill patients were entered into a 21-day prospective study to evaluate the feasibility of relying on a balanced nutritional support system to satisfy the needs of a diverse group of surgical patients. No patient sustained a serious complication related to glucose metabolism, and only two patients required insulin. Twenty-one of the patients achieved positive nitrogen balance during the study, and 13 had a significant weight gain not related to water retention. Documented sepsis was present in 50% of the patients but in spite of this, 91% had a successful course of therapy. The ease of management and metabolic efficiency of this approach encourages the use of fat as a primary energy substrate in a balanced nutritional support system to restore positive energy and nitrogen balance.

Adult↗
PubMed1981

Glucose-dependent changes in growth hormone regulation associated with sepsis.

Major alterations in the glucose-mediated regulation of growth hormone are associated with sepsis; however, these alterations are not related to the rate of change in plasma glucose or changes in glucagon, epinephrine levels, or circulating levels of arginine. Alterations in the growth hormone regulatory mechanism occurred among septic patients who manifested severe glucose intolerance which was associated with suppression of insulin production. Inhibition of growth hormone release in these patients may have an adverse effect on amino acid movement, which lends further support to the concept that sustained hyperglycemia in the septic patient is undesirable.

Adult↗
PubMed1980

Sepsis, glucose intolerance, and protein malnutrition: a metabolic paradox.

Glucose intolerance and its hormonal influence was examined in patients with sepsis. Eighteen patients were included in the protocol, which studied the response to a standard intravenous glucose tolerance test (GTT) in the postoperative stressed, septic, and septic protein malnourished (depressed albumin level) states. Four groups could be defined: stress (1), sepsis with depressed albumin level and normal glucose tolerance (2), sepsis with mild glucose intolerance and normal albumin levels (3), and sepsis with severe glucose intolerance and depressed albumin (4). Serial hormone levels were measured during the GTT, including insulin, glucagon, epinephrine, and human growth hormone values. Each group demonstrated a characteristic hormone profile. In a comparison with controls, group 2 was associated with mild suppression of insulin; group 3 exhibited mild glucose intolerance, hyperglucagonemia, and increased insulin; and group 4 demonstrated severe glucose intolerance, hyperglucagonemia, and marked suppression of growth hormone production.

Glucagon↗
PubMed1979

The sepsis-glucose intolerance riddle: a hormonal explanation.

Glucose intolerance has been commonly observed in sepsis and has been attributed to a multitude of endocrine and metabolic disorders. From 1977 to 1978, 19 patients were studied using intravenous glucose tolerance tests to evaluate this phenomenon; 15 patients presented with ongoing sepsis and four patients served as stress controls. Glucose intolerance was found to be a significant finding in less than 40% of the septic group. This state of intolerance was noted to be associated with a high mortality rate (60%), whereas glucose tolerance in sepsis was associated with a much improved mortality rate (10%). Hormone levels were correlated with glucose tolerance curves using the parameters of insulin, glucagon, growth hormone, cortisol, and epinephrine levels. Glucose intolerance and a high mortality rate were linked to sustained hyperglucagonemia, which was unresponsive to glucose challenge, and to marked suppression of growth hormone. This apparently represents a decompensated peripheral metabolic energy deficit, which results in the increased mortality rate.

Bacterial Infections↗
PubMedDate not supplied

Anabolic steroid administration during nutritional support: a therapeutic controversy.

Nitrogen balance was determined in 48 patients who were entered into a randomized prospective double-blind study, comparing anabolic steroids versus placebo in our parenteral nutritional support system. The group included both young and old patients suffering from catabolic illnesses, in whom intravenous feeding ranged from 14-21 days. All participants received the active agent or placebo biweekly throughout the study. During the period of intravenous nutrition, there was statistically significant difference in nitrogen balance and protein conservation in the patients receiving the active agent.

Anabolic Agents↗