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Biomedical subjects

D Landau

Publications and source records attributed to D Landau.

At least 55 records · Page 3Linked to original sources
PubMed1998

The variability of the photoplethysmographic signal--a potential method for the evaluation of the autonomic nervous system.

The heart rate variability is composed of low- and high-frequency fluctuations, which are mediated by the sympathetic and the parasympathetic nervous systems. The baseline and the amplitude of the photoplethysmographic (PPG) signal also show fluctuations in the same frequencies. In the current study, PPG examinations were performed on the fingers of normal subjects and diabetic patients, and three parameters were derived from each PPG pulse: the baseline of the pulse, its amplitude and its period (which is equal to the heart period). The level of the variability of each PPG pulse parameter was measured by the ratio of the standard deviation of the parameter to its mean value. The level of the low-frequency fluctuations for the PPG amplitude and for the heart cycle period did not differ between males and females, but was lower for diabetic patients, indicating lower activity of the autonomic nervous system. The curves of the baseline and the amplitude of the PPG signal for the non-diabetic subjects showed high correlation between the left and the right hands. For most of the diabetic patients the right-left correlation coefficients were significantly lower than those for the non-diabetic subjects. Our initial results have shown that the variability of the PPG parameters shows promise for the assessment of the function of the autonomic nervous system.

Adult↗
PubMed1998

Clinical presentation and outcome in primary familial hypomagnesaemia.

The clinical presentation and long term outcome (mean follow up eight years, range 0.25 to 21) of 15 patients with autosomal recessive primary familial hypomagnesaemia is described. The most common (67%) presenting events were generalised hypocalcaemic-hypomagnesaemic seizures at a mean (SD) age of 4.9 (2.5) weeks. Thirteen infants, treated soon after diagnosis with high dose enteral magnesium developed normally. Their serum calcium returned to normal concentrations but serum magnesium could not be maintained at normal concentrations (0.53 (0.12 SD) mmol/l; normal > 0.62). Delay in establishing a diagnosis led to a convulsive disorder with permanent neurological impairment in two infants. Reported complications of prolonged hypomagnesaemia such as renal stones, hypertension, arrhythmias, sudden death, or dyslipidaemia were not observed.

Consanguinity↗
PubMed1998

Retinal thickness variation in the diabetic patient measured by the retinal thickness analyser.

AIM: To evaluate the potential of the retinal thickness analyser (RTA) as an objective tool for assessment and follow up of diabetic macular oedema. METHODS: A prototype of the RTA that operates on the principle of laser slit biomicroscopy was used. Retinal thickness was obtained in 41 eyes of 41 diabetic patients. The clinical diagnosis was cystoid macular oedema (CMO) in 10 eyes, clinically significant macular oedema (CSMO) without retinal cysts in 21 eyes, and "dry" macula following grid pattern laser treatment in 10 eyes. The control group consisted of 46 eyes of age matched healthy volunteers. RESULTS: In normal eyes (46 eyes), the foveal thickness measured was 178 (SD 44) microns and the macular thickness around the fovea was 311 (51) microns. The eyes with CMO displayed the largest foveal thickening, 875 (287) microns (390% increase compared with normal values). The average thickness of the fovea in the non-cystoid CSMO group was 427 (175) microns (144% increase compared with normal fovea). The average thickness of the foveal centre in eyes judged as having "dry" macula after laser treatment was 315 (71) microns (77% increase compared with normal value and a 26% decrease in thickness compared with the CSMO eyes). Statistically significant differences were found in central thickness between these four groups (p = 0.0001). The average thickness at 500 microns surrounding the fovea was 566 (202) microns in the CSMO eyes compared with 311 (51) microns in normal eyes (80% increase). The "dry" macula group (after undergoing laser treatments) had an average thickness of 414 (94) microns (27% decrease compared with CSMO eyes and a 33% increase compared with eyes of healthy controls). CONCLUSIONS: RTA is a system for quantifying macular thickness and imaging of macular pathology. The system can be a useful tool for diagnosis of macular diseases and for evaluation of the effect of treatment modalities.

Adult↗
PubMed1997

Gentamicin-induced Bartter-like syndrome.

Gentamicin is well known to be associated with nephrotoxicity, including acute renal failure and renal tubular dysfunction. A Bartter-like syndrome has also been described as a toxic manifestation of gentamicin therapy in adults, but this nephrotoxic syndrome has not been well characterized in children. In this report we describe the clinical course of four patients with gentamicin-associated Bartter-like syndrome. These patients ranged in age from 4 months to 17 years; they all demonstrated evidence of renal tubulopathy, primarily affecting the distal nephron. Hypocalcemia, hypomagnesemia, alkalosis, and hypokalemia were the main manifestations in these patients. After discontinuation of gentamicin, recovery of the renal tubular functions and resolution of the electrolyte abnormalities were complete in all patients.

Adolescent↗
PubMed1997

Quantitative in vivo retinal thickness measurements in healthy subjects.

PURPOSE: The early detection of visual threatening retinal thickness alterations is important for the purpose of offering affected patients proven treatment when indicated. Currently, the clinical methods that are available for obtaining an impression of retinal thickness are subjective and require experience and expertise. The authors present measurements of foveal thickness in healthy individuals obtained by a newly developed instrument that enables a noninvasive, noncontact, safe, and fast measurement of the retinal thickness anywhere in the posterior pole. METHODS: A prototype of the retinal thickness analyzer (RTA) that operates on the principle of laser-slit biomicroscopy was used. Retinal thickness was measured in healthy emmetropic volunteers. RESULTS: Fifty eyes were measured. The average thickness at the foveola was 178 +/- 44 microm (+/- standard deviation; range, 100-322 microm). CONCLUSION: The retinal thickness measured by the RTA in healthy subjects correspond well to previous published data (in vivo and histologic) on retinal thickness. This instrument may prove valuable in detecting retinal thickness alteration in macular diseases.

Adolescent↗
PubMed1997

Exudative age-related macular degeneration in patients with diabetic retinopathy and its relation to retinal laser photocoagulation.

PURPOSE: To study the relationship between exudative age-related macular degeneration and diabetic retinopathy and assess the influence of retinal laser photocoagulation for diabetic retinopathy on the occurrence of exudative age-related macular degeneration. METHODS: Two groups, one of diabetic retinopathy patients treated with laser and the other of non-laser-treated diabetic retinopathy patients, were studied by means of fundoscopy and fluorescein angiography for the presence of exudative age-related macular degeneration. RESULTS: Exudative age-related macular degeneration was not observed in 431 patients treated with laser photocoagulation, and was diagnosed in 3.3% of 151 non-laser-treated patients. CONCLUSION: Patients treated by laser photocoagulation for diabetic retinopathy are less prone to develop the exudative form of age-related macular degeneration.

Age Distribution↗
PubMed1997

Changes in facilitative glucose transporter messenger ribonucleic acid levels in the diabetic rat kidney.

Facilitative glucose transporter (GLUTs 1, 2, 4, and 5) messenger RNAs (mRNAs) are differentially distributed in the rat nephron: GLUT1 is widely expressed, GLUT4 is selectively concentrated in thick ascending limbs, and GLUT2 and 5 are exclusively localized in proximal tubules, consistent with differential roles for these transporters in renal glucose handling. In the present study, quantitative in situ hybridization was used to evaluate changes in these mRNA levels during acute (2 and 7 days) and chronic (30, 90, and 180 days) streptozotocin-induced diabetes mellitus (STZ-DM). Medullary GLUT1 and GLUT4 mRNA levels were significantly increased during the acute phase but returned to normal after 1 week. Cortical GLUT1 mRNA levels, however, were decreased significantly from 7 days through 6 months of STZ-DM. Cortical GLUT2 mRNA was slightly increased acutely and increased 5-fold in chronic STZ-DM, with the largest increase focally concentrated in the convoluted portion of the proximal tubule. Proximal tubule GLUT5 mRNA levels also were increased significantly during chronic STZ-DM. In summary, medullary GLUT1 and GLUT4 mRNA levels are acutely increased in STZ-DM, paralleling the increased renal epithelial metabolic activity accompanying early diabetes. Proximal tubular GLUT2 and 5 mRNA levels were increased in chronic STZ-DM, possibly adapting to the increased need for glucose transport out of these epithelial cells, whereas the concomitant decrease in cortical GLUT1 expression may reflect the decreased requirement for basolateral import of glucose into these same cells. Thus, renal GLUTs demonstrate complex, nephron segment-specific and duration-dependent responses to the effects of STZ-DM.

Acute Disease↗
PubMed1997

Phase II trial of 13-cis-retinoic acid for poor risk HIV-associated Kaposi's sarcoma.

Fifteen men with HIV-associated Kaposi's sarcoma (KS) and poor risk disease according to the TIS staging were enrolled in a phase II trial of oral 13-cis-retinoic acid. The median CD4 cell count was 95 cells/microl (range 7-260) and 6 had prior AIDS-defining opportunistic infections. One patient was withdrawn on account of cutaneous toxicity. Evaluation was by AIDS Clinical Trials Group (ACTG)1 defined assessment. One patient achieved a partial response and remains on treatment in partial remission. Thus the overall response rate is 7% (95% confidence interval 0-23%). A further 5 patients had stable disease (38%: 95% confidence interval 7-64%). The overall low activity, considerable toxicity and limited cosmetic benefit even in responding patients limits the value of this approach in KS. However, this treatment strategy may be more rewarding in early good risk KS.

AIDS-Related Opportunistic Infections↗
PubMed1997

Renal hypertrophy in hyperglycemic non-obese diabetic mice is associated with persistent renal accumulation of insulin-like growth factor I.

The non-obese diabetic mouse is a model of spontaneous insulin-dependent diabetes as a result of autoimmune destruction of pancreatic beta cells, similar to the disease seen in human Type I diabetes. This mouse strain develops glomerular lesions reminiscent of those seen in human disease. The study presented here investigated the changes in renal insulin-like growth factor (IGF) system in hyperglycemic non-obese diabetic mice. Female non-obese diabetic mice and their age- and sex-matched controls were euthanized 4 days, 2 wk, and 4 wk after the onset of glycosuria. Kidney weight increased in diabetic mice, beginning at 2 wk after the onset of glycosuria. This renal hypertrophy was associated with an increase in renal extractable IGF-I protein. However, a decrease in IGF-I mRNA was observed at the same time. Serum IGF-I levels remained stable after 2 wk of diabetes and decreased at 1 month. No change was detected in renal IGF-I receptor mRNA levels. Renal cortical IGF binding protein (IGFBP)-1 mRNA levels were increased. Ligand blot analysis revealed a significant increase in serum and renal 30-kd IGFBP and a decrease in serum and kidney IGFBP-3 and IGFBP-4 at 30 days of diabetes. Insulin therapy prevented the increases in kidney weight, renal IGF-I, and 30-kd IGFBP, but did not reverse the decreased serum IGF-I levels observed at 1 month of diabetes. In summary, renal hypertrophy in non-obese diabetic mice is associated with a persistent accumulation of renal IGF-I and, IGFBP-1. These changes were partially reversed with insulin therapy, which did not correct the hyperglycemia, suggesting an important role for insulin deficiency in mediating these changes in the IGF system. These findings suggest that the IGF system may play a potential role in the development of diabetic nephropathy.

Animals↗
PubMed1996

Anaesthetic management of a patient with glycogen storage disease type 1b.

PURPOSE: A rare case of a ten-year old patient with type 1b glycogen storage disease (GSD), scheduled for extracorporeal shockwave lithotripsy (ESWL), is described. CLINICAL FEATURES: Patients with type 1b GSD manifest a range of clinical symptoms, including mental retardation, hepatosplenomegaly, renal enlargement, stomatitis, hypoglycaemic convulsions, bleeding diathesis, lactic acidosis and leukopaenia, thus creating a challenge for the anaesthetist. Following preanaesthetic administration of glucose-containing fluids, general anaesthesia was induced and the patient was mechanically ventilated. Except for mild hypoglycaemia after induction of anaesthesia, and moderate intraoperative metabolic acidosis which was attributed to the underlying disorder, anaesthesia was uneventful. No postoperative complications occurred and the patient was discharged home three days after lithotripsy. Clinical features of this rare inborn error of metabolism are reviewed and the approach for the anaesthetic management is discussed. CONCLUSIONS: A skillful perioperative management of patients with type 1b GSD can be achieved by cautious attention to the metabolic and homeostatic derangements that occur with the disease.

Anesthesia↗
PubMed1996

Protein C and protein S in pediatric nephrotic patients.

Nephrotic syndrome (NS) is associated with an increased incidence of various thromboembolic complications in adult patients. It was found to be due to elevated factor IX (FIX) F.VII, F.VIII, F.V, fibrinogen, thrombocytosis and increased platelet reactivity. Acquired AT-III deficiency, reduced functional levels of protein S and reduced activity of protein C were also reported. We evaluated 15 children aged 1 to 13 years. Thirteen of these children suffered from nephrotic syndrome and two others had non-nephrotic proteinuria. All patients but one were normotensive. Two patients were not steroid responsive. Serum creatinine was normal for age in 14 patients. Kidney biopsy was carried out only in three children. Haemostatic parameters included protein C and S antigenicity in plasma and urine. Plasma levels of protein C and protein S were within the normal range. Protein C antigenicity in urine was increased in five children out of 14 examined. Protein S in urine was increased in seven out of 12 children examined. No thromboembolic phenomena were documented even though protein C and protein S antigenicity were identified in the urine.

Adolescent↗
PubMed1995

Infantile variant of Bartter syndrome and sensorineural deafness: a new autosomal recessive disorder.

The infantile variant of Bartter syndrome (IBS) is usually associated with maternal polyhydramnios, premature birth, postnatal polyuria and hypokalemic hypochloremic metabolic alkalosis and a typical appearance. IBS is thought to be an autosomal recessive trait. Several congenital tubular defects are associated with sensorineural deafness (SND). However, an association between the IBS and SND has not been reported so far. Here we describe 5 children of an extended consanguineous Bedouin family with IBS and SND. In 3 of the cases, the typical electrolyte imbalance and facial appearance were detected neonatally. SND was detected as early as age 1 month, suggesting either coincidental homozygotization of 2 recessive genes or a pleiotropic effect of one autosomal recessive gene. This association suggests that evaluation of SND is warranted in every case of IBS.

Adolescent↗
PubMed1995

The effect of normal childbirth on eyes with abnormalities predisposing to rhegmatogenous retinal detachment.

BACKGROUND: Pregnant women who have high myopia, a history of retinal detachment or retinal holes, or have known lattice degeneration are frequently referred to an ophthalmologist for advice concerning the management of pregnancy and labor, i.e. whether a spontaneous vaginal delivery can be allowed and whether prophylaxis for high-risk retinal pathology is indicated. Many obstetricians still believe that pregnant women with ocular abnormalities predisposing to rhegmatogenous retinal detachment should have an instrumental delivery, and a few even advocate cesarian section. Very little has been written about the management of pregnant women with high-risk retinal pathology, and opinions differ considerably. Patient data on this subject are scarce. METHODS: We studied 10 women who had 19 deliveries (10 prospective and 9 retrospective) and who had a history of retinal detachment, had been diagnosed as having extensive lattice degeneration, or had been treated for symptomatic retinal holes or breaks. The women were followed from the third trimester of pregnancy through labor and delivery into the postpartum period, looking for changes in the retinal status. RESULTS: We found no changes in the retinal status in the postpartum examination. CONCLUSION: We conclude that prenatal treatment of asymptomatic retinal pathology is not indicated and that spontaneous vaginal delivery may be allowed to take place in women with high-risk retinal pathology.

Adult↗
PubMed1995

Carriage of Streptococcus pyogenes among infants and toddlers attending day-care facilities in closed communities in southern Israel.

Infants and toddlers attending ten day-care facilities in closed communities in southern Israel were tested monthly for pharyngeal carriage of Streptococcus pyogenes and associated respiratory morbidity. Overall, the prevalence of Streptococcus pyogenes was 2.7% in infants and 8.4% in toddlers, reaching 8.5% and 17.8% in the two groups, respectively by midwinter. In 4 of 61 (6.6%) infants and 15 of 67 (22.4%) toddlers, the organism was recovered in more than one month (range 2 to 5 months). Streptococcus pyogenes in the pharynx was only associated with rhinitis during the spring and summer but not with other respiratory symptoms. During the study period, a mean of 0.9 strains were isolated in day-care facilities attended by infants, while a mean of 2.1 strains were found in toddlers. Young children attending day-care facilities show early acquisition of Streptococcus pyogenes in the pharynx.

Carrier State↗
PubMed1995

The role of growth hormone, insulin-like growth factors (IGFs), and IGF-binding proteins in experimental diabetic kidney disease.

Early renal changes in type I diabetes are characterized by an increase in renal size, glomerular volume, and kidney function, and later by development of mesangial proliferation, accumulation of glomerular extracellular matrix, and increased urinary albumin excretion (UAE). Growth hormone (GH) and insulin-like growth factors (IGFs) have a long and distinguished history in diabetes mellitus, with possible participation in the development of long-term complications. In experimental diabetes in dwarf rats with isolated GH and IGF-I deficiency, a slower and lesser renal and glomerular hypertrophy is observed as compared with diabetic control animals with intact pituitary. Furthermore, diabetic dwarf rats with a diabetes duration of 6 months display a smaller increase in UAE, indicating that GH and IGF-I may be involved in the development of diabetic kidney changes. In line with this, administration of octreotide to streptozotocin (STZ)-diabetic animals with normal pituitary inhibits initial renal growth without affecting blood glucose levels, and 6 months' administration of octreotide to diabetic rats reduces long-term renal/glomerular hypertrophy and UAE. In addition, the initial increase in renal size and function in experimental diabetes is preceded by an increase in renal IGF-I, IGF-binding proteins (IGFBPs), and IGF-II/mannose-6-phosphate receptor (IGF-II/Man-6-P receptor) concentration. Finally, specific changes occur in renal GH-binding protein (GHBP) mRNA, IGF-I receptor mRNA, and IGFBP mRNA expression in long-term diabetes. In conclusion, the knowledge we have today indicates that GH and IGFs, through a complex system consisting of GHBP, IGFs, IGF receptors, and IGFBPs, may be responsible for both early and late renal changes in experimental diabetes.

Animals↗
PubMed1995

High-pressure directed water jets as a cause of severe bilateral intraocular injuries.

PURPOSE: To draw attention to the characteristic features of eye injuries caused by high-pressure water jets. METHOD: We examined three patients with bilateral eye injuries caused by directed high-pressure water jets. RESULTS: All three patients had reduced visual acuity bilaterally, extensive eyelid ecchymosis, subconjunctival hemorrhages, hyphema, iris sphincter rupture, transient increase in intraocular pressure, and inferior commotio retinae. These injuries were confined primarily to the lower parts of the eyes. CONCLUSIONS: High-pressure water jets may cause bilateral eye injuries affecting primarily the anterior and inferior parts of the eyes. Because of concern about late effects of injuries, long-term follow-up is recommended.

Adult↗
PubMed1995

Expression of insulin-like growth factor binding proteins in the rat kidney: effects of long-term diabetes.

Recent studies have shown that the renal synthesis of insulin-like growth factor binding proteins (IGFBPs) is altered in insulin-deficient diabetes mellitus, suggesting that these changes may be implicated in the alterations in renal function and morphology that accompany diabetes. To investigate the time course and the precise cellular distribution of changes in IGFBP expression, we used quantitative in situ hybridization to analyze renal IGF-I and IGFBP-1 to -5 messenger RNA (mRNA) localization and levels from 2 days to 6 months after the onset of streptozotocin-induced diabetes. There was an immediate sharp decline in IGF-I mRNA levels in the outer medulla that persisted for up to 3 months and a much smaller reduction in IGF-I mRNA levels in the medullary thick ascending limbs (MTALs). In nondiabetic animals, IGFBP-1 mRNA is most abundant in the MTALs. Immediately after the induction of diabetes, however, there was a greater than 2-fold increase in cortical IGFBP-1 mRNA and a 75% decrease in IGFBP-1 mRNA in MTALs. These changes persisted for up to 6 months in the diabetic animals. In contrast, IGFBP-5 mRNA levels were increased in the outer medulla and decreased in the cortex of diabetic kidneys. No significant changes in renal IG-FBP-2 mRNA levels or distribution were noted, and changes in IG-FBP-3 and -4 mRNA levels were subtle. In summary, streptozotocin-induced diabetes is associated with very prominent and complex alterations in renal IGF system gene expression, including robust increases in cortical IGFBP-1 and profound decreases in cortical IG-FBP-5 mRNA and medullary IGF-I mRNA levels. The divergent changes in IGFBP-1 and -5 mRNA levels in cortex vs. outer medulla indicate that regulation of IGFBP mRNA levels is quite complex.

Albuminuria↗