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Biomedical subjects

M Hero

Publications and source records attributed to M Hero.

At least 19 recordsLinked to original sources
PubMed2005

Anatomical success rate of macular hole surgery with autologous platelet without internal-limiting membrane peeling.

AIM: To describe our experience and success rate of macular hole surgery with pars plana vitrectomy with autologous platelet and without internal limiting membrane peel. METHODS: Retrospective review of 56 consecutive patients who underwent macular hole surgery. RESULTS: Anatomical success was achieved in 55 out of 56 patients (98.2%). Functional success was achieved in 37 out of 56 patients (66.1%). A total of 21 patients (37.5%) achieved postoperative visual acuity of 6/12 or better. No intraoperative complications were encountered. Postoperative complications included cataract progression in eight eyes and raised intraocular pressure in 20 eyes. CONCLUSIONS: Our success rate was comparable to that reported in macular hole surgery incorporating internal limiting membrane (ILM) peel or with autologous platelet without ILM peel.

Aged↗
PubMed1999

Intraindividual variability of infant whole-body plethysmographic measurements: effects of age and disease.

The intraindividual variability of whole-body plethysmographic measurements was studied in a large series of consecutive infants (N = 144), divided into two groups: a group of infants born very prematurely (PM, N = 63), with (N = 28) or without (N = 35) a history of bronchopulmonary dysplasia (BPD), and a group of infants with persistent respiratory symptoms (PRS, N = 81), i.e., wheezing (N = 53) or cough (N = 28). The intraindividual variability was determined within each test and between tests, separated by a 10-min interval. In both study groups, the between-test variability was significantly larger than that within tests. Expressed as the median coefficient of variation (CV), the between-test repeatabilities in the PRS group were 8.0% for thoracic gas volume (TGV), 17.5% for airway resistance (Raw), and 18.4% for specific airway conductance (sGaw), and in the PM group, 8.9% for TGV, 20.4% for Raw, and 20.7% for sGaw. However, the individual range of CVs was large, ranging from 3 to 19% for TGV and from 5 to 55% for sGaw. With respect to TGV, the difference between the groups was statistically significant (P = 0.03). In infants with a history of BPD, there was also a significant negative age dependency in CVs of sGaw (r = -0.50, P = 0. 009), showing larger variation among younger individuals. The presenting symptom (wheezing or cough) in the PRS group did not influence the measurement variability significantly, and neither did the degree of bronchial obstruction. We conclude that on a group basis, the repeatability of infant body plethysmographic measurements may be satisfactory for scientific studies demonstrating pharmacodynamic effects; however, the intraindividual measurement variability should be reported for each test conditions and for infant groups in each study. Due to the large range in individual variation and the influence of age and disease processes on the variation, for an individual child there is only questionable benefit from a given measurement, unless the intrasubject, between-test variability is assessed individually before interventions, such as a bronchodilation test.

Bronchopulmonary Dysplasia↗
PubMed1997

Photographic and angiographic characterization of the retina of Kenyan children with severe malaria.

OBJECTIVE: To investigate retinal lesions in children with severe falciparum malaria. METHODS: Color photography and fluorescein angiography were performed in consecutive children admitted to a pediatric high-dependency unit in Kenya during 1 malaria season. The presence and category of retinal lesion was compared with disease severity, clinical outcome, anemia, lactic acidosis, and parasite count. RESULTS: Twenty-six patients with cerebral malaria and 14 patients who were prostrate were studied. Thirty-one of the patients had clinical features of ocular disease, including round, flame-shaped, and white-centered hemorrhages; peripheral and foveal retinal opacification; peripheral vascular occlusion; venous dilation; disc edema with hyperemia; and arterial pulsatility. Of 8 patients with retinal opacification, only 2 showed small, infrequent zones of capillary nonperfusion on fluorescein angiography; the leakage of dye at sites of opacification was not seen. Retinal opacification was significantly associated with a higher parasite count (P < .02). White-centered hemorrhages were significantly associated with a higher parasite count (P < .05), severe disease (p < .05), and severe anemia (P < .02). CONCLUSIONS: The blood-retina barrier and retinal vascular flow remain substantially normal despite widespread pathological features. Retinal features in children with severe malaria are consistent with cellular hypoxia, nutritional deficiency, or both rather than with vascular occlusion; they support the concept of metabolic steal by parasites.

Blood-Retinal Barrier↗
PubMed1997

Autoregulation of human optic nerve head blood flow in response to acute changes in ocular perfusion pressure.

BACKGROUND: Studies in animals have demonstrated that optic nerve head (ONH) blood flow (F(onh)) is autoregulated, but there is a lack of evidence for such a process in humans. Therefore, we investigated the relationship between F(onh) and mean ocular perfusion pressure (PPm) in normal volunteers when PPm is decreased through elevation of the intraocular pressure (IOP). METHODS: Laser Doppler flowmetry (LDF) was used to measure relative mean velocity (Velohn), volume (Volonh) and F(onh) of blood at sites of the ONH away from visible vessels, while PPm was decreased in two ways: (1) rapidly, by IOP increments of 15 s duration, and (2) slowly, by IOP increments of 2 min duration, both by scleral suction cup in one eye of each of nine subjects. RESULTS: A rapid and large decrease of PPm of more than 100% induced a decrease of more than 80% in F(onh). With the slower decrease in PPm, F(onh) remained constant down to a PPm of approximately 22 mm Hg (IOP = 40 mm Hg) and then decreased, predominantly due to a decrease in Velohn. Immediately after removal of the suction cup, F(onh) increased transiently by 44% above baseline. CONCLUSIONS: This study demonstrates efficient blood flow autoregulation in the OHN, which is probably brought about by an increase in vascular capacitance. The magnitude of the reactive hyperaemia agrees with the compensatory decrease in ONH vascular resistance during IOP elevation. The time scale of the autoregulatory process and the dependence of the hyperaemia upon duration of IOP elevation suggest a metabolic mechanism of autoregulation.

Adult↗
PubMed1997

Conjunctival impression cytology in the preterm infant and it's relation to outcome.

UNLABELLED: The preterm infant is deficient in vitamin A (retinol) and this has been implicated in the pathogenesis of chronic lung disease of prematurity. Conjunctival impression cytology (CIC) has been used in adults to assess retinol status. We aimed to assess the feasibility of performing CIC in the preterm infant and to determine the significance of abnormal CIC findings. CIC samples were collected during routine retinopathy screening, and classified as inadequate, normal, borderline normal or abnormal. Ninety preterm infants were studied. Seventy-four (82%) CIC specimens produced a positive yield, whereas 16 (18%) were inadequate. Of the 74 adequate samples, 61 (82%) were normal or borderline normal and 13 (18%) abnormal. Seventy-three CIC specimens were assessed by a second histopathologist with complete agreement on 64 (88%) samples and disagreement on 9 (12%) samples. Ten sets of conjunctival impressions, taken from both eyes, gave identical results in all adequate samples. Birth weight was significantly lower in this abnormal group. Four infants (32%) in the abnormal group required treatment for retinopathy compared to two (3%) in the normal/borderline normal group, (P < 0.01). CONCLUSION: Conjunctival impression cytology is simple and reproducible technique which maybe easily applied to the preterm infant. Abnormal CIC is associated with retinopathy of prematurity requiring treatment.

Conjunctiva↗
PubMed1997

[Effect of changes in ocular perfusion pressure on choroid ischemia in man].

BACKGROUND: The effect of changes in ocular perfusion pressure (PPm) on the choroidal blood flow (ChBF) in man was studied with the laser Doppler flowmetry (LDF) technique. MATERIALS AND METHODS: We changed the PPm by increasing the intraocular pressure (IOP) or by increasing the blood pressure (BP) with isometric exercises. RESULTS: We observed that a) ChBF was not significantly different from baseline up to an IOP of 27 mm Hg and b) ChBF remained constant even if PPm increased by as much as 72%. CONCLUSION: Our results suggest that ChBF is autoregulated in response to an increase in IOP up to about 27 mm Hg. ChBF remains also constant in spite of an increase in systemic BP, probably due to a vasoconstriction induced by increased sympathetic activity.

Adult↗
PubMed1997

Effect of acute decreases of perfusion pressure on choroidal blood flow in humans.

PURPOSE: To investigate the relationship between choroidal blood velocity (ChBVel), blood volume (ChBVol) and blood flow (ChBF) in the foveal region of the human ocular fundus and ocular perfusion pressure and to determine whether the choroidal circulation has some autoregulatory capacity. METHODS: Measurements of ChBVel, ChBVol and ChBF were obtained by laser Doppler flowmetry in healthy subjects (age range, 21 to 57 years) with normal eye examination results. Measurements were performed at normal intraocular pressure (IOP) and during successive step increases in IOP induced by scleral suction. In experiment 1, in six eyes (five subjects), the IOP was increased rapidly, in steps of 50 to 100 mm Hg of suction pressure, which each lasted approximately 10 seconds to a level above diastolic ophthalmic artery blood pressure (IOP = approximately 72 mm Hg). In experiment 2, in 14 eyes (seven subjects), the IOP was increased slowly in four successive steps at 2-minute intervals to a level of approximately 42 mm Hg. We also determined the pulsatility of the flow parameters during the heart cycle, pulsatility = 1 - diast value/syst value. RESULTS: For both rates of suction cup increase, the relationship between ChBFm (mean ChBF over the heart cycle) and mean perfusion pressure was not linear. At high pressure, ChBFm was less affected by decreases in the pressure than expected from a passive vascular system. In some cases, no change in ChBFm was detectable, although significant changes in PChBF occurred. Further decreases in perfusion pressure resulted in a proportional decrease in ChBFm. On release of suction, a significant increase in ChBFm over baseline value was detectable in experiment 1. CONCLUSIONS: The relationship between ChBFm and ocular mean perfusion pressure appears to be bilinear and reveals some autoregulation for moderate step decreases in perfusion pressure. The temporal characteristics of the ChBFm-response suggest a neural or passive hemodynamical process rather than a myogenic or metabolic compensatory mechanism.

Adult↗
PubMed1997

[Autoregulation in ischemia of the optic nerve in the human].

BACKGROUND: Autoregulation is defined as the maintenance of constant blood flow in a vascular system in spite of changes in perfusion pressure (PPm). MATERIALS AND METHODS: PPm was decreased by increasing the intraocular pressure (IOP) with a suction cup and optic nerve blood flow was measured with the laser Doppler flowmetry technique (LDF) in 9 normal volunteers. RESULTS: The blood flow was autoregulated down to a PPm of 13 mm Hg (IOP = 47 mm Hg). CONCLUSIONS: These results confirm previous studies in cats and monkeys. The mechanism of autoregulation is probably a decrease in resistance due to capillary recruitment.

Adult↗
PubMed1997

Choroidal blood flow during isometric exercises.

PURPOSE: To investigate the response of choroidal blood flow in the foveal region of the human eye to increases in mean perfusion pressure (PPm = mean ophthalmic artery pressure - intraocular pressure; IOP) induced by isometric exercises. METHODS: Using laser-Doppler flowmetry, changes in velocity (ChBVel), number (ChBVol), and flux (ChBF) of red blood cells in the choroidal vascular system in the foveal region of the fundus were measured in both eyes of 11 normal subjects (ages 18 to 57 years) during isometric exercises. RESULTS: During 90 seconds of squatting, PPm increased by an average of 67%, from 46 to 77 mm Hg. This resulted in a significant increase of 12% in ChBFm (the mean of ChBF during the heart cycle), mainly caused by an increase in ChBVelm. A further increase in PPm to a value approximately 85% above baseline resulted in a 40% increase in ChBFm. A significant negative correlation was found between the changes in ChBVelm and ChBVolm, during squatting. CONCLUSIONS: Previous studies have demonstrated that during isometric exercise, blood pressures in the ophthalmic and brachial arteries rise in parallel. These observations and the current results indicate that an increase in PPm up to 67% induces an increase in choroidal vascular resistance that limits the increase in choroidal blood flow to approximately 12%. This regulatory process fails when PPm is further increased.

Adolescent↗
PubMed1995

The chemotherapy of onchocerciasis XVIII. Aspects of treatment with suramin.

We report the clinical and parasitological effects of a modified treatment regimen for suramin. Twenty adult males received up to 5 g (72.5 to 84.7 mg/kg) of suramin over 36 days. Detailed clinical and laboratory examinations were done before treatment and then at intervals over 2 years. Nodules were removed at 6, 13, 26 and 52 weeks for histology. Systemic tolerance was good. Anterior segment inflammation was however common and 2 patients required intervention to prevent posterior synechiae. No new posterior segment lesions developed; a rare improvement occurred in one patient with papillitis. Proteinuria, mostly mild, occurred in nearly all patients. Previously unreported renal glycosuria was documented in one patient. Microfilariae in the skin and anterior chamber did not change significantly for 5 or more weeks after which rapid reductions occurred. Ocular parasites were absent at 2 years and skin microfilariae were near zero. Peripheral blood eosinophil counts fell in parallel with those of microfilariae in the skin and anterior chamber and were normal at one and two years. These findings at 2 years may provide indirect evidence of a macrofilaricidal or a permanent chemosterilant effect on the adult worms. Nodule examination revealed an embryotoxic effect from week 6, a lethal effect on the male worms from month 3 and on the female worms from month 6 after treatment started. At one year 34% of the female worms examined were alive. Thus total doses of suramin in the range 72.5 to 84.7 mg/kg have only a modest lethal effect on the female worms. Suramin remains a restricted drug and a suitable replacement is urgently needed.

Adult↗
PubMed1994

Indirect diode laser treatment for stage 3 retinopathy of prematurity.

Eight infants with stage 3+ retinopathy of prematurity (ROP) were treated using the diode laser through a binocular indirect ophthalmoscope. Two infants with zone I disease were treated prethreshold as soon as the signs of plus disease developed. Successful regression was achieved in all cases, though 3 infants required repeat treatment. All infants were followed up for a minimum of 3 months. Keeler acuity scores were in the normal range in 4 of the 8 infants.

Female↗
PubMed1994

The chemotherapy of onchocerciasis XVII. A clinical evaluation of albendazole in patients with onchocerciasis; effects of food and pretreatment with ivermectin on drug response and pharmacokinetics.

Three pharmacokinetic studies were conducted in Ghanaian patients in support of investigations of albendazole and its combination with ivermectin in the treatment of onchocerciasis. These included dose-finding studies, investigations into the influence of a fatty meal on the relative bioavailability of albendazole as assessed by the measurement of concentrations of albendazole sulphoxide and the effect of prior treatment with ivermectin on antiparasitic efficacy and plasma concentrations of albendazole suphoxide. Increasing the dose of albendazole from 800 mg x 3 daily to 1200 mg x 3 daily produced no additional antiparasitic effects although plasma concentrations of albendazole sulphoxide were increased in proportion to dose size. Moreover, the plasma concentration vs time profiles suggest that most of the effects observed may have been due to the first 800 mg dose. Administration of ivermectin had no effect on the pharmacokinetics of albendazole sulphoxide and there was no additive effect on the parasite. Albendazole was well tolerated and its administration 5-7 days after ivermectin produced little additional reaction. Although it is not macrofilaricidal, it does possess important chemosterilant properties which are enhanced by its administration with a fatty breakfast. Under these conditions, the relative bioavailability of albendazole is increased four-fold. These studies support further work with albendazole administered with food either as a single dose, as multiple single doses repeated at intervals of several months and its coadministration with ivermectin. They also encourage the belief that a more potent and bioavailable benzimidazole may be macrofilaricidal or a permanent chemosterilant for Onchocerca volvulus on single dosage.

Adolescent↗
PubMed1992

Quantification of the ocular reactions to microfilaricides in the chemotherapy of onchocerciasis.

Severe adverse systemic and ocular reactions have complicated the chemotherapy of onchocerciasis. A method for the quantification of ocular reactions to chemotherapy has been devised at the Onchocerciasis Chemotherapy Research Centre, at Hohoe, in Ghana. Symptoms, visual function, anterior segment inflammation and disease of the posterior segment are graded. The information is entered into a computerised database which allows reaction scores to be calculated both for individual patients, and for treatment groups. This system enables comparison of adverse ocular reactions to various new chemotherapeutic regimens.

Anterior Eye Segment↗
PubMed1991

The chemotherapy of onchocerciasis. XV. Studies with albendazole.

Ninety-two males, infected with Onchocerca volvulus, from an area of on-going transmission in the forest zone of southern Ghana were treated with albendazole. 31 patients received 800 mg daily x 3, 31 received 1200 mg daily x 3 and 30 others received 800 mg daily x 7. Albendazole was given as a single daily dose with a fatty breakfast. Detailed systemic, ocular and laboratory examinations were performed pretreatment and at intervals over one year. Nodules were extirpated on days 30 and 60 and examined by histopathology. All the dose regimes were well tolerated but were neither microfilaricidal nor macrofilaricidal. The main effect was embryotoxicity affecting all intra-uterine stages. The most encouraging results were obtained in the 800 mg daily x 3 group in which a prolonged suppression of skin microfilarial counts occurred. Controlled studies in combination with ivermectin are recommended to determine whether an additive effect of the two drugs would result in permanent sterilisation of the adult worms.

Adult↗