PubMed Health⌕ Search

Biomedical subjects

L Ohman

Publications and source records attributed to L Ohman.

At least 37 records · Page 2Linked to original sources
PubMed1995

Induction of a metabolic switch in insect cells by substrate-limited fed batch cultures.

Insect cell metabolism was studied in substrate-limited fed batch cultures of Spodoptera frugiperda (Sf-9) cells. Results from a glucose-limited culture, a glutamine-limited culture, a culture limited in both glucose and glutamine, and a batch culture were compared. A stringent relation between glucose excess and alanine formation was found. In contrast, glucose limitation induced ammonium formation, while, at the same time, alanine formation was completely suppressed. Simultaneous glucose and glucosamine limitation suppressed both alanine and ammonium formation. Although the metabolism was influenced by substrate limitation, the specific growth rate was similar in all cultures. Alanine formation must involve incorporation of free ammonium, if ammonium formation is mediated by glutaminase and glutamate dehydrogenase, as our data suggest. On the basis of the results, two possible pathways for the formation of alanine in the intermediary metabolism are suggested. The cellular yield on glucose was increased 6.6 times during glucose limitation, independently of the cellular yield on glutamine, which was increased 50-100 times during glutamine limitation. The results indicate that alanine overflow metabolism is energetically wasteful and that glutamine is a dispensable amino acid for cultured Sf-9 cells. Preliminary data confirm that glutamine can be synthesized by the cells themselves in amounts sufficient to support growth.

Alanine↗
PubMed1995

Correlation between susceptibility of infants to infections and interaction with neutrophils of Escherichia coli strains causing neonatal and infantile septicemia.

The ability of Escherichia coli strains causing invasive infections to associate to human neutrophils and induce oxygen radicals was studied in three groups of blood isolates from neonates and infants: low-virulence septicemia strains (LVS), normal septicemia strains (NS), and meningitis strains (M). Infants were classified by susceptibility to infection as low- (LR) or high-risk (HR). All LVS strains were isolated from HR infants and showed higher association to neutrophils (P < .05) and induced a higher oxidative response (P < .05) compared with that of NS and M strains from LR infants. Three LVS strains caused the cells to release oxidative metabolites extracellularly. Thus, impaired interaction with neutrophils is characteristic of virulent clones of E. coli capable of causing invasive infection in healthy full-term neonates. Furthermore, increased extracellular release of oxygen metabolites could harm the surrounding tissue and potentiate the inflammatory process.

Bacteremia↗
PubMed1994

Phototherapeutic keratectomy in herpes simplex keratitis. Clinical results in 20 patients.

Twenty eyes in 20 patients with herpetic keratitis were treated with excimer laser photoablation. Sixteen eyes underwent phototherapeutic keratectomy because of scars and surface irregularities, with the goal to improve vision and 1 eye for cosmetic reasons. Two eyes had slight scars but were treated because of a refractive error (PRK). One eye had a metaherpetic ulcer where the wound surface was ablated with the intention to improve healing. Twelve of the 16 eyes showed improved visual acuity of 2 lines or more on the Snellen chart. The refractive outcome was acceptable in the 2 PRK eyes. The cosmetic result was good and the metaherpetic wound epithelialized within 3 weeks. Of the 20 patients 5 had 1 or more recurrences during the 16.8 months of follow-up. In the 17 months preceding the laser surgery 9 eyes had 1 or more recurrences. Three of these eyes still showed improved vision. Phototherapeutic excimer laser surgery is advantageous in selected cases and should be considered before corneal grafting. The procedure does not seem to increase the incidence of recurrences.

Adolescent↗
PubMed1994

Treatment of recurrent corneal erosions with the excimer laser.

Seventy-six patients with recurrent corneal erosions resistant to conventional therapy with ointment, abrasion or contact lenses were treated with the excimer laser. The patients were treated in 3 different ways; ablation of 3 or 5 microns after epithelial removal, or ablation of 20 microns directly on the epithelium. Twenty out of the 76 treated eyes showed recurrences. Thirty-five of the patients had no symptoms after treatment and 21 patients had minor symptoms. The 3 different treatment modes were equally successful in the present study.

Adult↗
PubMed1994

The chemiluminescence response of neutrophils on polymer surfaces made by glow discharge plasma polymerization.

Polypropylene tubes were coated with different polymers made by glow discharge plasma polymerization. Isolated human blood neutrophils were allowed to interact with the polymer surface and the chemiluminescence response of the cells was recorded as a measure of oxidative activation. The polymers represented surfaces that differed markedly with respect to charge, hardness, and wettability. We found that all polymers stimulated the chemiluminescence response in neutrophils differently; when preincubation with human serum albumin (HSA) there was a general reduction of the chemiluminescence response particularly on one of the positively charged surface 1,2-diamino-cyclohexane (DACH). Addition of a soluble stimulus, the chemoattractant formylmethionyl-leucylphenylalanine (FMLP), to the cells caused a dramatic increase in the response on one of the hydrophobic surface hexamethylene-disiloxane (HMDSO). However, there was also a pronounced reduction in the response on polymers with acrylic acid (AA). The response was normalized after addition of HSA. Taken together, the chemiluminescence response of the neutrophils interacting with the polymer surfaces differed with regard to the type of surfaces. When HSA and FMLP were added a larger difference in the response was found. Our results showed that the activation of human neutrophil granulocytes influenced by different polymer surfaces, followed unspecific different patterns which were someway related to the specific characteristics of the polymer and from this point we came to similar conclusions made by Kaplan et al. (J. Biomater. Res. 28, 377 (1994)), that it is difficult to extrapolate any activation mechanisms from one material to another.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylates↗
PubMed1993

Nebulae at keratoconus--the result after excimer laser removal.

Ten patients underwent excimer laser ablation due to nebula formation at keratoconus. The nebulae interfered significantly with contact lens fit or wearing time. The mean follow-up time in these patients was 16.5 months. Following surgery all patients could be successfully fitted with a contact lens and thereby obtain good visual acuity. Furthermore, contact lens wearing time was 8 hours or more in all cases. In 2 patients the nebulae recurred but were successfully retreated.

Adult↗
PubMed1992

In vivo insulin action in genetic models of hypertension.

Insulin resistance has been described in nonobese subjects with essential hypertension. At present it is unknown whether hypertension per se may lead to the onset of insulin resistance. To examine this question we studied in vivo insulin action in two rat models of genetic hypertension. Four groups of conscious rats were studied: Milan hypertensive (MHS), Milan normotensive (MNS), spontaneously hypertensive (SHR), and Wistar-Kyoto (WKY). Mean arterial pressure was increased in SHR vs. WKY in both the fed (184 +/- 5 vs. 126 +/- 6 mmHg; P less than 0.001) and fasting (160 +/- 5 vs. 129 +/- 5; P less than 0.001) states. During high-dose insulin clamps, total body glucose uptake (mg.kg-1.min-1) was similar in MNS (28.7 +/- 1.4) vs. MHS (33.6 +/- 3.0) and in WKY (34.6 +/- 1.8) vs. SHR (35.7 +/- 2.4). During low-dose insulin clamps, suppression of hepatic glucose production (3.5 +/- 0.6 vs. 3.0 +/- 0.5 mg.kg-1.min-1) and stimulation of glycolysis (12.9 +/- 0.8 vs. 14.4 +/- 1.5 mg.kg-1.min-1) were similar in WKY vs. SHR, whereas glucose uptake (24.6 +/- 1.9 vs. 18.3 +/- 1.2 mg.kg-1.min-1; P less than 0.01) and muscle glycogenic rate (10.2 +/- 1.1 vs. 6.5 +/- 1.1 mg.kg-1.min-1; P less than 0.05) were increased in SHR vs. WKY. In conclusion, 1) feeding markedly augments blood pressure in hypertensive but not in normotensive rats, and 2) hepatic and muscle insulin sensitivity are normal or increased in two different rat models of genetic hypertension. These results provide evidence that high blood pressure per se does not invariably lead to the development of insulin resistance.

Animals↗
PubMed1992

Increased insulin sensitivity in the high sodium one-kidney, one figure-8 hypertensive rat.

This study examines the relation between sympathetic activity and in vivo insulin-mediated glucose metabolism in a rat model of acquired hypertension. Two groups of conscious, unrestrained rats were studied in the postabsorptive state: sham-operated normotensive rats (n = 10) and renal-wrapped hypertensive rats (n = 10). Mean arterial pressure was increased in the hypertensive compared with the normotensive group in the fed (184 +/- 9 versus 144 +/- 6 mm Hg; p less than 0.01) and in the fasting (147 +/- 8 versus 112 +/- 7 mm Hg; p less than 0.01) state. After a 24-hour fast, hepatic glucose production, plasma glucose, insulin, and norepinephrine concentrations were similar in the two groups. Blood pressure did not change in either group during the 3-milliunits/kg.min euglycemic insulin clamp study; however, plasma norepinephrine concentration rose significantly in hypertensive (207 +/- 24 versus 329 +/- 11 pg/ml; p less than 0.05) but not in normotensive rats (229 +/- 23 versus 267 +/- 27 pg/ml; p = NS). During the insulin clamp study, the hepatic glucose production was similar in the hypertensive (3.8 +/- 0.8 mg/kg.min) compared with the normotensive (4.0 +/- 0.3 mg/kg.min) rats. Insulin-mediated glucose uptake was significantly higher in hypertensive than in normotensive rats (33.0 +/- 0.7 versus 25.8 +/- 0.8; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

N-acetylcysteine enhances receptor-mediated phagocytosis by human neutrophils.

The effect of the sulphur compound N-acetylcysteine (NAC) on certain receptor-mediated cellular functions [chemiluminescence (CL), phagocytosis and degranulation] in human neutrophils was studied, to evaluate how a scavenger of certain toxic oxygen product can protect the phagocyte and the bystander tissue cells from oxidative damage. When using IgG-opsonized yeast particles as stimulating agent, preincubating the neutrophils with NAC (0.25 mg/ml = 1.5 mM) increased both the CL response and phagocytosis. Higher concentrations of NAC (0.50-1.00 mg/ml = 3-6 mM) decreased the CL response, whereas the phagocytic capacity was still enhanced. This effect was more pronounced with adherent neutrophils than with neutrophils in suspension. No increased CL or phagocytic activity was, however, induced by NAC when C3bi-opsonized particles were used as a prey. From the fact that NAC (i) inhibited extracellularly localized myeloperoxidase dependent activities, and (ii) had no effect on neutrophils from patients with chronic granulomatous disease (CGD), we conclude that the scavenger effect of NAC not only reduces the accumulation of oxidative metabolites per se, but also enhances receptor-mediated phagocytosis by protecting Fc(IgG)-receptors from oxidative damage mediated by myeloperoxidase (MPO) and hydrogen peroxide (H2O2). Since NAC can increase phagocytosis and reduce the extracellularly produced oxidative metabolites, we furthermore conclude that NAC possesses some ideal properties as an anti-inflammatory agent.

Acetylcysteine↗
PubMed1991

The melanophore aggregating response of isolated fish scales: a very rapid and sensitive diagnosis of whooping cough.

Pertussis toxin (PT) has been found to block noradrenaline-induced pigment aggregation in fish melanophores, and, based on this, a rapid and highly sensitive assay for PT was developed. Some preliminary results have also indicated that it may be possible to detect PT-like activity in saliva samples from patients with clinically suspected pertussis. In the present study the diagnostic value of the fish melanophore method was evaluated in 70 patients suspected of having pertussis; culture, serology and physician diagnosis were used as reference methods. In 60 of the patients, pertussis was verified by at least one of the reference methods. The melanophore test showed PT-like activity in saliva samples from 58 of the patients. Three patients with reference-verified pertussis showed no PT-like activity in the test; among these, one patient had been immunized and had also been treated with erythromycin during 3 days immediately prior to visiting the hospital. The melanophore test has three major advantages: it allows detection of pertussis in the early and curable stage of the disease; it takes only 2 h to perform; and it requires no sophisticated equipment.

Adolescent↗
PubMed1991

Extracellular release of reactive oxygen species from human neutrophils upon interaction with Escherichia coli strains causing renal scarring.

The production of reactive oxygen metabolites by neutrophils plays a key role in the host defense against invading microorganisms and in tissue damage resulting from infection. In the present study we measured the ability of different uropathogenic Escherichia coli strains to induce generation of oxygen metabolites upon interaction with human neutrophils. The strains were selected to represent two groups of patients with recurrent episodes of acute pyelonephritis: one with renal scars (12 strains) and one without renal scarring (11 strains). The majority of strains (from both groups) induced a pronounced neutrophil respiratory burst activity. When the intracellular and extracellular oxidative responses were measured separately, it was found that the response induced by nonscarring strains was primarily of intracellular (intraphagosomal) origin, whereas a proportionally larger fraction of the response induced by the scarring strains was extracellular. Since reactive oxygen products are toxic to the renal tissue, this release can be of importance in the development of renal scars.

Antigens, Bacterial↗
PubMed1990

Heparin surface modified intraocular lenses--a one-year follow-up of a safety study.

PMMA intraocular lenses have been modified by bonding a monolayer of Heparin molecules to the surface. These Heparin surface modified (HSM) IOLs were implanted in the capsular bag after extracapsular cataract extraction. Sixty-six patients were followed for 12 months in an open safety study. No unexpected reactions or severe complications occurred. Eighty-nine per cent of the patients obtained a visual acuity (VA) of 0.5 or more at the 12-month visit. When excluding cases with preoperative pathology only one case (1.5%) had less VA than 0.5. A mild postoperative iritis was seen during the first week after surgery, and in only three cases at a later visit. Cell precipitates were seen in a small number of cases. From this study and from earlier in vitro and in vivo animal studies we draw the conclusion that the Heparin surface modified IOLs are safe for implantation in human eyes.

Aged↗