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Biomedical subjects

M Hedberg

Publications and source records attributed to M Hedberg.

At least 19 recordsLinked to original sources
PubMed1992

Effect of beta-lactamase inhibitors on beta-lactamases from anaerobic bacteria.

Three beta-lactamase inhibitors in clinical use--clavulanic acid, sulbactam and tazobactam--were investigated for their activity on beta-lactamases from Bacteroides uniformis, Clostridium butyricum and Fusobacterium nucleatum. Purification of the beta-lactamases was carried out by anion-exchange chromatography, gel filtration and FPLC. The inactivation of beta-lactamase activity was determined spectrophotometrically with nitrocefin as substrate. Various concentrations of the inhibitors were preincubated at 30 degrees C together with the enzyme for different periods of time before determination of the beta-lactamase activity. The three beta-lactamases tested were more susceptible to tazobactam than to clavulanic acid and sulbactam. Clavulanic acid and sulbactam reduced the enzyme activity of the Bacteroides uniformis beta-lactamase more effectively than the Clostridium butyricum and Fusobacterium nucleatum beta-lactamases.

Bacteria, Anaerobic↗
PubMed1992

Purification and characterization of an imipenem hydrolysing metallo-beta-lactamase from Bacteroides fragilis.

An imipenem resistant beta-lactamase producing strain of Bacteroides fragilis was isolated from a clinical specimen. The specific activity of the unpurified beta-lactamase was 5.5 U/mg protein. The beta-lactamase was purified 60-fold by Q Sepharose, Sephacryl S-300 and Mono Q column passages. The strain was able to inactivate imipenem and cefoxitin in broth cultures. The enzyme hydrolysed imipenem more rapidly than ampicillin, benzylpenicillin, cephalothin and cefoxitin. The activity of the enzyme was Zn2+ dependent and was completely inhibited by EDTA. The inhibition was reversed by ZnSO4. Preincubation with the common beta-lactamase inhibitors clavulanic acid, sulbactam and tazobactam did not reduce the enzyme activity. The molecular weight was determined by sodium dodecyl sulfate gradient gel electrophoresis to be 31,000 Daltons and the isoelectric point was 4.5.

Bacteroides fragilis↗
PubMed1992

Effect of clavulanic acid, sulbactam and tazobactam on three different beta-lactamases from Bacteroides uniformis, Clostridium butyricum and Fusobacterium nucleatum.

The effect of three beta-lactamase inhibitors, clavulanic acid, sulbactam and tazobactam used in clinical practice were compared for their activity against purified beta-lactamases from Bacteroides uniformis, Clostridium butyricum and Fusobacterium nucleatum. The enzymes from B. uniformis and C. butyricum were produced in fermenters under controlled growth conditions and the enzyme from F. nucleatum was produced in batch cultures. Purification of the beta-lactamases was achieved by anion-exchange chromatography, gel filtration and FPLC-technique. The degree of inactivation of beta-lactamase activity was determined spectrophotometrically with nitrocefin as the substrate. The inhibitors in various concentrations were preincubated at 30 degrees C together with the enzyme for different time periods (0.5-120 min) before determination of the remaining beta-lactamase activity. The inhibitors all decreased the activity of the beta-lactamases investigated. Clavulanic acid and sulbactam were capable of reducing the enzyme activity of the B. uniformis beta-lactamase more effectively than the C. butyricum and F. nucleatum beta-lactamases. All beta-lactamases tested were more susceptible to tazobactam than to clavulanic acid and sulbactam.

Bacteroides↗
PubMed1992

Compensatory muscle fiber hypertrophy in elderly men.

Muscle strength and muscle morphology have been studied three times during a period of 11 yr in nine elderly men. On the last occasion the average age was 80.4 (range 79-82) yr. Body cell mass decreased by 6% and muscle strength for knee extension, measured by means of isometric and concentric isokinetic (30-60 degrees/s) recordings, declined by 25-35% over the 11-yr period. Between 76 and 80 yr of age only the isokinetic strength for 30 degrees/s decreased significantly. Muscle fiber composition in the vastus lateralis did not change between 69 and 76 yr of age, but there was a significant reduction in the proportion of type IIb fibers from 76 to 80 yr. The decrease in type II fiber areas was not significant between 69 and 76 yr of age (as in a larger sample from the same population), but a significant increase in both type I and type II fiber areas was recorded from 76 to 80 yr of age and biceps brachii showed similar tendencies. In the same period, the enzymatic activities of myokinase and lactate dehydrogenase subsided in the vastus lateralis, but there was no change for triose phosphate dehydrogenase, 3-hydroxy-CoA-dehydrogenase, and citrate synthase. The muscle fiber hypertrophy in this group of elderly men with maintained physical activity between 76 and 80 yr of age is interpreted as a compensatory adaptation for the loss of motor units. In addition, the adaptation with respect to oxidative capacities seems to be maintained at this age.

Adaptation, Physiological↗
PubMed1992

Training can improve muscle strength and endurance in 78- to 84-yr-old men.

Nine men, 78-84 yr of age, participated in a dynamometer training program 2-3 times/wk, totaling 25 sessions, using voluntary maximal isometric, concentric, and eccentric right knee-extension actions (30 and 180 degrees/s). Measurements of muscle strength with a Kin-Com dynamometer and simultaneous electromyograms (EMG) were performed of both sides before and after the training period. Muscle biopsies were taken from the right vastus lateralis muscle. The total quadriceps cross-sectional area was measured with computerized tomography. Training led to an increase in maximal torque for concentric (10% at 30 degrees/s) and eccentric (13-19%) actions in the trained leg. The EMG activity increased at maximal eccentric activities. The total cross-sectional quadriceps area of the trained leg increased by 3%, but no changes were recorded in muscle fiber areas in these subjects, who already had large mean fiber areas (5.15 microns 2 x 10(3)). The fatigue index measured from 50 consecutive concentric contractions at 180 degrees/s decreased and the citrate synthase activity increased in all but one subject. The results demonstrate that increased neural activation accompanies an increase in muscle strength at least during eccentric action in already rather active elderly men and that muscle endurance may also be improved with training.

Aged↗
PubMed1992

Pancreatico-duodenectomy: 13-years' experience.

This paper reports a retrospective study of 51 consecutive pancreatico-duodenectomies from a Swedish university hospital concerning postoperative morbidity, number of reoperations and mortality. Resection of the distal common bile duct, duodenum, and head of the pancreas with hemigastrectomy and cholecystectomy was done in 48 patients and modified pancreaticoduodenectomy with preservation of the pylorus was done in three patients. Three patients (6%) died within 30 days. Nine patients required reoperation, three more than once. The most common major complications were anastomotic breakdown (n = 7), severe hemorrhage (n = 3) and abscess formation (n = 3). We conclude that a low postoperative morbidity and mortality can be achieved outside large, specialist centres, but the operation should be done by experienced surgeons. The results may justify carrying out the operation when the chances of cure are small, but it has yet to be evaluated as a palliative procedure.

Adult↗
PubMed1990

Detection and quantitation by lysis-filtration of bacteremia after different oral surgical procedures.

Patients with bacteremia after dental extraction, third-molar surgery, dental scaling, endodontic treatment, and bilateral tonsillectomy were studied by means of lysis-filtration of blood samples with subsequent aerobic and anaerobic incubation. Samples were obtained before, during, and 10 min after treatment. Bacteremia was observed in 100% of patients after dental extraction, 55% of patients after third-molar surgery, 70% of patients after dental scaling, 20% of patients after endodontic treatment, and 55% of patients after bilateral tonsillectomy. Anaerobic microorganisms were isolated more frequently than aerobic microorganisms were, and viridans group streptococci were the most commonly isolated bacteria. Ten minutes after treatment, the frequency as well as the magnitude of bacteremia showed pronounced reduction.

Adolescent↗
PubMed1989

Purification and characterization of a new beta-lactamase from Clostridium butyricum.

A highly penicillin-resistant beta-lactamase-producing strain of Clostridium butyricum, strain NBL 3, was isolated. The specific activity of the unpurified beta-lactamase was 0.29 U/mg of protein. The enzyme was purified 1,130-fold by QAE Zetaprep, Sephacryl S-300, and Mono Q column passages. The purified enzyme was judged homogeneous by sodium dodecyl sulfate gradient gel electrophoresis and fast protein liquid chromatography. The enzyme hydrolyzed phenoxymethylpenicillin, benzylpenicillin, ampicillin, and carbenicillin more rapidly than piperacillin and cephaloridine. Cephalothin, cephalexin, cefoxitin, moxalactam, cefotaxime, and imipenem were only slightly hydrolyzed, at less than 1% the rate for phenoxymethylpenicillin. The enzyme was inhibited by clavulanic acid, sulbactam, tazobactam, and p-chloromercuribenzoate. The molecular weight was determined by gel filtration and sodium dodecyl sulfate gradient gel electrophoresis to be 32,000. The isoelectric point was 4.4. Aspartic acid-asparagine, glutamic acid-glutamine, leucine, lysine, alanine, and serine dominated the amino acid composition.

Amino Acids↗
PubMed1989

Muscle adaptive changes in post-polio subjects.

Nineteen post-polio subjects (9 men and 10 women) aged 41-65 years were studied by means of muscle strength measurements (Cybex) of knee extension and muscle biopsies of the vastus lateralis for morphometric, histopathological and enzymatic analyses. Data from a reference group of 10 male subjects, age 42-51 years, are also given. Fourteen of the post-polio subjects had experienced a post-polio syndrome-like drop in function. All had had polio at least 25 years earlier. In nine of the 19 subjects, type I fibers accounted for more than 70% of the total. There was a significant negative correlation between muscle strength and the percentage of type I fibers in women. Large cross-section areas of muscle fibers were found, with an average mean fiber area of 8 microns 2 X 10(3). It is assumed that the large muscle fiber areas are due to an extreme use of the remaining muscle fibers in post-polio subjects with low muscle strength. There were significant negative correlations between muscle strength values and mean fiber area in men. Most subjects had single atrophic fibers; groups of atrophic fibers were less common. Internal nuclei and splitting were seen in about half of the subjects. The activity of citrate synthase was low, but normal for glycolytic enzymes.

Adult↗
PubMed1988

Muscle function and morphology in myotonic dystrophy.

Patients with myotonic dystrophy classified clinically into function groups were studied. Muscle strength for knee extension and flexion was, with few exceptions, moderately or markedly reduced with successively more severe clinical disability. The reduction in maximal walking speed showed a similar tendency. There was a large percentage of both type I and in relation to normal findings of type II C fibers in biopsies from most patients. The fiber area varied greatly even in the patients in the best function groups, some of whom had large type II fibers. The most common-histopathological changes, found in all function groups, were fiber atrophy with small angular fibers, internal nuclei, splitting, fibrosis and moth-eaten fibers. A high percentage of type I fibers can already be seen in patients with practically no other morphological changes and without significant functional deterioration.

Adult↗
PubMed1988

A micromethod for determination of antimicrobial agents in bone.

A microtechnique, requiring very small amounts of tissue material, was developed for assay of antimicrobial agents in bone. Without previous homogenization or extraction, small bone pieces (mean weight 0.014 g) from human subjects and pigs were placed into wells in agar plates preinoculated with the test strain. Round and distinct zones of inhibition were formed around the pieces. Standards for ampicillin and flucloxacillin were prepared from freeze-dried bone pieces from human subjects and pigs with known amounts of antibiotics as well as in human plasma and phosphate-buffered saline (PBS). Curves obtained from these standards were linear. Bone pieces from human and pig maxilla gave superimposable curves, but differed from curves obtained in plasma or PBS. The method was used in a pharmacokinetic study of bacampicillin in human maxillary bone and plasma. Bacampicillin tablets (2 X 400 mg) were given to patients before oral surgery. Standardized bone pieces and plasma samples were obtained at different times during surgery. The peak ampicillin concentrations estimated from the population curves were 8.0 mg/l in plasma and 1.1 mg/l in maxillary bone. The elimination half-life of ampicillin was similar in plasma and maxillary bone.

Ampicillin↗
PubMed1986

Muscle morphology, enzymatic activity, and muscle strength in elderly men: a follow-up study.

A follow-up study of muscle strength, muscle morphology, and enzymatic activity in 23 men, 73-83 years of age, was performed 7 years after the first investigation. With the exception of two men treated for congestive heart failure and four treated for hypertension, all were apparently clinically healthy and none had functional locomotor disturbances. Body weight was reduced by 2% and body cell mass by 6%, whereas the quadriceps muscle strength decreased 10%-22% over the 7-year period. Fiber composition in the vastus lateralis did not change significantly, and there was no significant difference between the biopsies from the biceps brachii and vastus lateralis. In the vastus lateralis, there was a reduction in fast-twitch fiber areas, which were smaller than in the biceps brachii (not studied at the previous investigation). There were also more histopathologic changes in the vastus lateralis than in the biceps brachii. The enzymatic activities of lactate dehydrogenase and myokinase, which were studied on both occasions in the vastus lateralis, did not change, and the activities of the other measured enzymes indicated a maintained metabolic capacity at high age. Oxidative enzymatic activities were higher in the vastus lateralis, and glycolytic enzymatic activities were higher in the biceps brachii, which could partly be explained by differences in relative fiber areas.

Aged↗
PubMed1985

Recognition of psychological and cognitive impairments in the emergency department.

Ninety-six patients presenting to a university hospital emergency department were screened before triage for psychological symptoms or cognitive impairment using the General Health Questionnaire (GHQ) and Mini-Mental State examination (MMS). Charts were reviewed for demographic information and emergency physicians' recognition of psychological symptoms or cognitive dysfunction. Of the patients studied, 38% had positive results on the GHQ, and 18% had positive results on the MMS. Psychological symptoms or cognitive impairments were recognized by the emergency physicians in only 8% of those with positive GHQ results and 6% of those with positive MMS results. The usefulness of screening measures for psychological symptoms and cognitive impairment of emergency department patients is discussed.

Cognition Disorders↗