Biomedical subjects

M Larsen

Publications and source records attributed to M Larsen.

At least 73 records · Page 4Linked to original sources

PubMed1999

Acute orbital compartment syndrome after lateral blow-out fracture effectively relieved by lateral cantholysis.

PURPOSE: To report the observation of an acute traumatic orbital compartment syndrome in an 80-year-old man. METHODS: Lateral canthotomy and cantholysis. Computed x-ray tomography. RESULTS: Unilateral proptosis, blindness, a frozen globe and a dilated pupil developed within one hour after a blunt trauma to the left orbital region. Surgery two hours later resulted in normal orbital tension and near-complete recovery of functions. An orbital hematoma was found overlying a lateral blow-out fracture. CONCLUSION: Under favorable conditions, the orbital compartment syndrome can be effectively relieved by lateral canthotomy and cantholysis. The present and previous reports suggest that two hours of orbital ischemia is near the critical time limit for recovery of full visual function.

Accidental Falls↗

PubMed1999

Detection of shallow detachments in central serous chorioretinopathy.

PURPOSE: To study the correlation between symptoms, clinical findings, fundus photographic morphology, and optical coherence tomography in patients with symptoms of central serous chorioretinopathy, but ambiguous biomicroscopic findings and no late-phase fluorescein angiographic leakage. METHODS: Biomicroscopic slit-lamp examination, greyscale digital fundus photography in red-free illumination, fundus fluorescein angiography, optical coherence tomography, and focal retinal argon laser photocoagulation. Seven consecutive patients aged 32-69 years, of whom four received focal retinal photocoagulation treatment. RESULTS: All patients demonstrated a shallow serous detachment on optical coherence tomography. After treatment the detachment resolved, as did the relative scotoma, the prolonged dark adaptation, and the dyschromatopsia. Micropsia was markedly reduced in all, but not completely eliminated in two of the patients. CONCLUSION: Patients with central serous chorioretinopathy may have shallow foveal detachments that can only be detected by optical coherence tomography, whereas clinical and angiographic signs of detachment may be missing. Classical symptoms coupled with a normal or only mildly reduced visual acuity are highly indicative of the presence of a serous neuroretinal detachment, but fluorescein angiography is necessary to establish the diagnosis and the target for treatment.

Adult↗

PubMed1999

Enhanced visualisation of acute macular neuroretinopathy by spectral imaging.

PURPOSE: To report photographic findings from a case of acute macular neuroretinopathy. METHODS: Fundus photography on color transparencies, red-free digital CCD-recording, and laser-scanning ophthalmoscopy with monochromatic red and blue illumination. RESULTS: The visibility of the retinal lesions was markedly enhanced by narrowing the illumination bandwidth and by the stray light suppression of the confocal laser scanning ophthalmoscope. CONCLUSIONS: The diagnosis of acute macular neuroretinopathy, and possibly other chorioretinal diseases as well, can be facilitated by multispectral imaging and stray-light reduction optics.

Adult↗

PubMed1999

A new isolate of the nematophagous fungus Duddingtonia flagrans a biological control agent against free-living larvae of horse strongyles.

An experiment was carried out in 1997 to test the efficacy of an isolate of the microfungus Duddingtonia flagrans against free-living stages of horse strongyles under conditions in the field and to assess the eventual effect of the fungus on the normal degradation of faeces. Faecal pats were made from faeces of a naturally strongyle infected horse, which had been fed fungal material at a dose level of 106 fungal unit/kg bwt. Control pats without fungi were made from faeces collected from the same animal just before being fed fungi. Faecal cultures set up for both groups of faeces to monitor the activity of the fungus under laboratory conditions showed that the fungus significantly reduced the number of infective third-stage larvae (L3) by an average of 98.4%. Five faecal pats from each batch of faeces were deposited on pasture plots at 3 times during spring-summer. The herbage around each pat was sampled fortnightly to recover L3 transmitted from faeces. The results showed that the herbage infectivity around fungus-treated pats was reduced by 85.8-99.4%. The remaining faecal material at the end of each sampling period was collected, and the surviving L3 were extracted. Significantly fewer larvae were recovered from the fungus-treated pats. Analysis of wet and dry weight of the collected pats, as well as their organic matter content, were performed to compare the degradation of faeces of both groups. The results indicated that the presence of the fungus did not alter the degradation of the faeces.

Animal Feed↗

PubMed1999

Diabetic versus non-diabetic colour vision after cataract surgery.

AIMS: To examine whether the colour vision abnormalities found in phakic patients with diabetes mellitus is preserved after removal of the lens by cataract surgery. METHODS: 21 diabetic (16 IDDM and five NIDDM) and 19 non-diabetic patients of comparable age, postoperative visual acuity, and sex distribution, all aphakic or pseudophakic following cataract surgery, had their monocular colour vision examined using the Farnsworth-Munsell 100 hue test. The fundus status of the diabetic patients ranged from no retinopathy to photocoagulation treated proliferative diabetic retinopathy. Patients with macular oedema were specifically excluded from the study. RESULTS: The error scores of both the diabetic (mean 146 (SD 94)) and the non-diabetic patients (83 (79)) did not deviate significantly from the age related normal range. The error score in the diabetic group was significantly higher than in the non-diabetic group (p=0.02) but the amplitude of the difference was small in comparison with previous studies of phakic subjects. The error scores in the diabetic group were not correlated with the degree of retinopathy (p>0.2). CONCLUSION: After cataract surgery only a minor difference exists between the colour vision scores of diabetic and non-diabetic patients. This indicates that accelerated yellowing of the lens in diabetes is the predominant cause of the colour vision anomaly found in phakic diabetic patients.

Adult↗

PubMed1999

Effects of acetazolamide on passive and active transport of fluorescein across the normal BRB.

PURPOSE: To investigate the effect of the carbonic anhydrase inhibitor acetazolamide (AZM) on passive permeability and active transport of fluorescein across the blood-retina barrier in healthy subjects. The study may have implications for the understanding of the edema-reducing effect of AZM. METHODS: The effect of AZM on the blood-retina barrier function was assessed by differential vitreous spectrofluorometry using fluorescein as a tracer. The study included fourteen healthy subjects in a randomized double-masked crossover trial with 3 days' treatment with AZM (500 mg/d) and placebo, respectively. The two examinations were separated by at least 1 week. Fluorescein concentration was determined separately from its metabolite fluorescein glucuronide. The passive permeability of fluorescein was determined by computerized modeling and curve-fitting to the preretinal curve and the plasma concentration curve obtained at 30 to 60 minutes after the injection of fluorescein. The unidirectional permeability due to outward active transport from vitreous to blood was estimated from the preretinal gradient and the plasma concentration at 7 to 10 hours after injection. RESULTS: Treatment with AZM was associated with significant increases in passive permeability and unidirectional permeability of fluorescein. For the passive permeability the increase was on average 0.3+/-0.4 nm/s (mean+/-SD; range, -0.8-1.0 nm/s), and for the unidirectional permeability the increase was on average 7.4 nm/s+/-7.0 (mean+/-SD; range, -3.3-19.0 nm/s). CONCLUSIONS: Acetazolamide caused an increase in passive permeability. Unidirectional permeability was increased by AZM, indicating a stimulation of the outward active transport of fluorescein. It has been proposed that the edema-reducing effect of AZM is due to stimulated ion and fluid removal from the retina to the choroid. The results of this study are consistent with AZM affecting the blood-retina barrier with stimulation of at least one ion transport mechanism.

Acetazolamide↗

PubMed1998

The effect of volatile anaesthetics on synaptic release and uptake of glutamate.

1. Volatile anaesthetics seem to exert their effects on several parts of the neuronal conducting system. 2. The effect on synaptic excitation seems to be quantitatively the most important (Berg-Johnsen and Langmoen, Acta Physiol. Scand. 128, 1986, 613-618) as 1 minimum alveolar concentration (MAC) of isoflurane reduces the activity in thin unmyelinated afferent fibres by 18%, excitatory synapses by 27% and postsynaptic neurones by 24%. 3. The reduction in excitatory synaptic transmission is caused by a decreased amount of transmitter glutamate in the synaptic cleft caused by a reduced release and increased uptake of glutamate in the presynaptic terminals (Larsen et al., Brain Res. 663, 1994, 335-337; Larsen et al., Br. J. Anaesth. 78, 1997, 55-59).

Anesthesia, Inhalation↗

PubMed1998

[Documentation of violence against civilians in a civil war. Examples from Kashmir].

Physicians for Human Rights/Denmark visited Kashmir three times in 1993 and 1994. In Indian-held Kashmir we examined victims of torture and gunshots and we assessed similar evidence collected by local lawyers and doctors. In refugee camps for Indian Kashmiries we examined ten children, who were reported to have been tortured at the age of 5-14 years, and ten other children who allegedly had been ill-treated. Furthermore, 17 adults, who reported that they had been tortured, were examined. In nearly all cases there were physical findings in accordance with the histories of torture. In many cases, including those of the children, the findings were highly remarkable by their shape and localization. We interpret them as evidence of intentionally inflicted injuries. In the refugee camps we carried out a prevalence study of exposure to organized violence. Approximately 95% of all families had been exposed to violence; 35% reported that their children had been ill-treated. The physical findings indicate that intentional traumatization of civilians including children in Indian-held Kashmir takes place; the results of the prevalence study suggest that exposure to violence is widespread.

Adolescent↗

PubMed1998

The potential of nematophagous fungi to control the free-living stages of nematode parasites of sheep: studies with Duddingtonia flagrans.

The nematophagous fungus, Duddingtonia flagrans, isolated from a fresh sheep faecal sample obtained from a farm in northern New South Wales, Australia, was subjected to a number of in vivo investigations in both surgically modified and normal sheep to determine its capacity to survive passage through the gastrointestinal tract. Single and sustained dosing experiments established that between 5 x 10(5) and 10(6) chlamydospores/day resulted in a substantial (> 80%) reduction in the number of infective larvae derived from nematode eggs in faeces. This effect can be maintained if dosing continues. These results demonstrate for the first time the potential of nematophagous fungi to be deployed by means of sustained release technology in the biological control of nematode parasites of livestock.

Animals↗

PubMed1998

Molecular cloning and expression of ps20 growth inhibitor. A novel WAP-type "four-disulfide core" domain protein expressed in smooth muscle.

We previously reported the purification of ps20 (Rowley, D. R., Dang, T. D., Larsen, M., Gerdes, M. J., McBride, L., and Lu, B. (1995) J. Biol. Chem. 270, 22058-22065), a urogenital sinus mesenchymal cell secreted protein having growth-inhibitory properties. We report here cloning of the 1.03-kilobase rat ps20 cDNA clone from the PS-1 (adult rat prostate smooth muscle) cDNA library. Partial clones were obtained by nested polymerase chain reaction with degenerate primers, and full-length ps20 cDNA clones were isolated by plaque hybridization. Sequence analysis revealed that ps20 protein contains a WAP-type "four-disulfide core" motif and is a novel member of the WAP signature protein family composed primarily of secreted serine protease inhibitors. Native ps20 immunoprecipitated from smooth muscle cells and recombinant ps20 both resolved on SDS-polyacrylamide gel electrophoresis with apparent molecular mass of 27-29 kDa under reducing conditions and 21-23 kDa under non-reducing conditions, respectively. Stable ps20-transfectant COS-7 cell lines secreted ps20 and were growth-inhibited relative to mock transfectants. In addition, COS-7 and prostate carcinoma PC-3 cells were growth-inhibited by bacterially expressed ps20. Northern analysis indicated differential expression by tissue with highest expression in the heart. Immunohistochemical localization of ps20 protein showed cell-specific expression by both visceral and vascular smooth muscle in all tissues, including the prostate gland. These results indicate ps20 is a novel growth-regulatory member of the WAP signature family expressed by smooth muscle cells.

Amino Acid Sequence↗

PubMed1998

Objective assessment of photoreceptor displacement and metamorphopsia: a study of macular holes.

BACKGROUND: We have developed a binocular perimetry technique for the quantitative assessment of retinal photoreceptor displacement and metamorphopsia. OBJECTIVE: To study the direction and amplitude of retinal photoreceptor displacement in eyes with idiopathic macular holes using our binocular perimetry technique. SUBJECTS: Five healthy control subjects and 10 patients with unilateral stage 3 to 4 macular holes in one eye and a healthy fellow eye. METHOD: Kinetic perimetry using red and green filter glasses, black binocular fixation targets, red and green selective monocular stimuli (Goldmann III-4-e), and fundus image superimposition of perimetry data. RESULTS: We found no discrepancy between the 2 visual fields in any healthy subjects. In patients with a unilateral macular hole, the central scotoma invariably extended beyond the rim of the hole. In 8 patients, each point on the rim of the scotoma had a perceptually corresponding location in the visual field of the fellow eye that was closer to the center of the visual field. In the 2 patients with the longest duration of symptoms (>2 years), no such discrepancy was found. CONCLUSIONS: Differential perimetry enables the objective study of retinal photoreceptor displacement and metamorphopsia. We found objective evidence for radial centrifugal photoreceptor displacement in most patients with idiopathic macular holes.

Aged↗

PubMed1998

Kluyveromyces lactis killer plasmid pGKL2: evidence for a viral-like capping enzyme encoded by ORF3.

ORF3 of the cytoplasmic linear plasmid pGKL2 was disrupted in vivo by integration of a selectable marker. Long-term cultivation of transformants carrying hybrid plasmids with a disrupted ORF3 under selective pressure did not deprive strains of the native counterpart, thereby proving its essentiality for pGKL2 replication and maintenance. The predicted ORF3 polypeptide was found to contain conserved motifs acquainted with mRNA-capping enzymes in the required order, just as in cytoplasmic viruses; new conserved motifs were also identified.

Acid Anhydride Hydrolases↗

PubMed1998

The effect of acetazolamide on passive and active transport of fluorescein across the blood-retina barrier in retinitis pigmentosa complicated by macular oedema.

BACKGROUND: The carbonic anhydrase inhibitor acetazolamide (AZM) reduces macular oedema in some patients with retinitis pigmentosa. To better understand the oedema-reducing effect of AZM, the effect of AZM on passive permeability and active transport of fluorescein across the blood-retina barrier was studied in patients with retinitis pigmentosa and varying degrees of macular oedema. METHOD: The selection of patients was based on an introductory examination including vitreous fluorometry for qualitative assessment of the vitreous. Macular oedema was graded by fluorescein angiographic leakage. The effect of AZM on the transport properties of the blood-retina barrier was determined by differential spectrofluorometry, in a randomised, double-masked, cross-over study, comprising 2 weeks' treatment with AZM (500 mg/day) and 2 weeks' treatment with placebo. The penetration ratio, defined as the ratio between vitreous concentration 3 mm in front of the retina and the plasma integral, was determined for fluorescein and its metabolite fluorescein glucuronide at 30-60 min and at 120 min after fluorescein injection. Passive permeability and unidirectional permeability in the direction vitreous to blood, due to outward active transport of fluorescein, were determined in those cases where the curves for vitreous concentration of fluorescein could be fitted to a mathematical model. Visual acuity was tested by use of ETDRS standard logarithmic charts. RESULTS: Twenty-two patients volunteered to participate in the study. Signs of significant vitreous detachment/liquefaction caused the exclusion of ten patients after the introductory examination. Nine patients with approximately intact vitreous and varying degrees of oedema completed the cross-over study. AZM treatment was related to a decrease in the penetration ratio of 21% for fluorescein (P=0.01) and of 22% for fluorescein glucuronide (P=0.004). Passive permeability and unidirectional permeability were determined in seven patients. AZM caused a decrease of 27% in the passive permeability of fluorescein (from 1.1 x 10(1) nm/s, P=0.031), and a 95% increase in unidirectional permeability of fluorescein (from 1.2 x 10(2) nm/s, P=0.047). AZM led to a reduction in the grade of macular oedema as determined by fluorescein angiography in three out of seven patients. Only small improvements (< or =5 letters) in visual acuity were noted. CONCLUSION: The present study indicates that the oedema-reducing effect of AZM is due to decreased leakage and stimulated active transport across the blood-retina barrier.

Acetazolamide↗

PubMed1998

Precipitation of hard exudate after resorption of intraretinal edema after treatment of retinal branch vein occlusion.

PURPOSE: To present evidence that precipitation of hard exudate in the retina can occur after reduction of macular edema by successful photocoagulation treatment for retinal branch vein occlusion. METHODS: A 59-year-old woman received argon laser retinal photocoagulation treatment for retinal branch vein occlusion over the primarily involved engorged area of the retina. Fundus changes were documented by fundus photography and optical coherence tomography. RESULTS: Before treatment, an extensive intraretinal edema with cavity formation and a small serous foveal detachment extended outside the engorged area of the retina. Three months after treatment, all retinal thickening had disappeared, but a markedly increased amount of intraretinal hard exudate was seen adjacent to the treated area. CONCLUSIONS: Precipitation of hard exudate can occur after reduction of macular edema by successful retinal photocoagulation treatment, presumably because water and highly soluble electrolytes are resorbed faster than lipids. This phenomenon should be distinguished from accumulation of hard exudate resulting from disease progression.

Chemical Precipitation↗

PubMed1998

Dung-derived biological agents associated with reduced numbers of infective larvae of equine strongyles in faecal cultures.

Two sets of dung-derived organisms from soil routinely fertilized with manure (MA) and soil chemically fertilized (CH) were cultured separately in the laboratory. Baermannized organisms from these cultures were added to 20 g of faeces from strongyle-infected horses to form three treatment groups: (i) no soil organisms; (ii) low inoculum of soil organisms containing all organisms present in a suspension of approximately 100 adult female free-living nematodes; and (iii) high inoculum containing those soil organisms present with approximately 1000 adult female free-living nematodes. Three studies were conducted using MA cultures and faeces containing 50 stronglye epg, CH cultures and faeces containing 1500 strongyle epg, and a mixture of soil organisms from the two cultures (MC) and faeces containing 600 strongyle epg. Within each study, five control cultures and 15 each of low and high inoculum cultures were prepared and incubated at 24 degrees C and 95% humidity in a climate chamber for 15 days. Parasitic and free-living nematodes were then recovered by the Baermann technique and counted. The numbers of third stage larvae were significantly lower in the high inoculum group compared to controls. The percent reductions in the number of third stage larvae for the low and high inoculum groups were 63.6% and 90.9%, 85.1% and 97.1%, 84.5% and 98.4% for MA, CH, and MC studies, respectively, indicating that mortality increased with the number of soil organisms added to cultures. Examination of the source cultures detected the presence of two species of nematophagous fungi and three genera of free-living nematodes reported to be predacious.

Animals↗

PubMed1998

Bilateral optic neuritis in acute human immunodeficiency virus infection.

PURPOSE: To report a case of acute viral disease accompanied by bilateral optic neuritis with substantial paraclinical evidence that human immunodeficiency virus was the causative agent. METHODS: Clinical and paraclinical examination. Magnetic resonance imaging. RESULTS: Virus and antibody titers as well as reverse lymphocytosis were consistent with acute infection by the human immunodeficiency virus-1. CONCLUSIONS: Human immunodeficiency virus infection should be considered in the differential diagnosis of acute optic neuritis.

Acute Disease↗

PubMed1998

Effect of isoflurane on release and uptake of gamma-aminobutyric acid from rat cortical synaptosomes.

We have studied the effect of isoflurane on potassium-evoked release and high-affinity uptake of gamma-aminobutyric acid (GABA) in rat cortical synaptosomes. Isoflurane 1.5% and 3% increased calcium-dependent release by 38% and 36% of control values, respectively (P < 0.05). Calcium-independent release was reduced correspondingly by 24% and 26% (P < 0.05). High-affinity uptake of GABA was not affected by isoflurane. The findings of increased synaptic GABA release combined with unaltered uptake suggest that isoflurane increases GABA in the synaptic cleft and thus may enhance inhibition.

Anesthetics, Inhalation↗

PubMed1998

The effect of isoflurane on brain amino acid release and tissue content induced by energy deprivation.

This article describes the effect of isoflurane on amino acid release and tissue content induced by energy deprivation in slices of rat hippocampus. Energy deprivation (95% N2 / 5% CO2 and glucose free medium) (ED) induced an increase in the release of all amino acids measured, with the exception of glutamine. The tissue content of all amino acids except gamma-aminobutyric acid (GABA) and arginine was concomitantly reduced. Isoflurane (1.5% and 3.0%) reduced glutamate release during ED by 27% and 28% (p < 0.05 as compared with release without isoflurane), respectively, whereas the tissue content was slightly increased. Similarly, GABA release was reduced by 25% and 25% (p < 0.05 as compared with release without isoflurane) accompanied by an insignificant enhancement in tissue content as compared with ED without isoflurane. Isoflurane reduced the release of taurine and most of the other amino acids. The total amount of all amino acids (both released and retained) was not significantly altered by the anesthetic. These observations demonstrate that isoflurane can modify the changes in amino acid handling induced by energy deprivation.

Amino Acids↗