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Biomedical subjects

A Pollak

Publications and source records attributed to A Pollak.

At least 127 records · Page 7Linked to original sources
PubMed1990

Quantitative analysis of cochlear sensory cells and neuronal elements in man.

The myelinated radial fibres in the osseous spiral lamina and the myelinated fibres in the cochlear nerve in the internal auditory canal as well as the sensory cells were counted in cochleae from 15 dissected temporal bones from 8 patients. Light microscopy was carried out on semithin sections of epoxy resin embedded tissue. Audiometry had been performed within 6 months prior to death. Three patients had normal hearing for their age group, 2 had slight presbyacusis and the remaining 3 had sustained noise injury. All specimens clearly had fewer fibres in the spiral lamina than in the internal auditory canal. The cochleae from patients with normal hearing for their age group had a difference in the nerve fibre counts of up to 34%. A case of sensorineural presbyacusis showed 31%, and a case of neural presbyacusis, 47% difference. The greatest difference was found in a case of acoustic trauma, the range in this group being between 25% and 55%. The lower the number of fibres in the spiral lamina, the greater was the difference in all but two specimens. A slow retrograde degeneration, i.e. beginning in the peripheral process of the cochlear nerve, could be an explanation for these findings.

Aged↗
PubMed1990

Observations on the pattern of sensorineural degeneration in the human cochlea.

Cochlear sensory and neural degeneration was examined in nine pairs of human temporal bones fixed by perilymphatic perfusion, using phase-contrast and electron microscopy. Four pairs, three from females, had only slight sensorineural degeneration, limited to the very basal end of the cochlea. A predominantly neural degeneration was identified in a 54-year-old male. The process was bilateral, asymmetrical, uneven, and involved the entire length of the cochlea with several circumscribed areas of severe nerve degeneration. One case had mild, diffuse sensorineural degeneration in the lower half of the basal turn characteristic of presbyacusis. The other three pairs, all from males, revealed sensorineural degeneration patterns associated with noise injury and were remarkably similar to or almost identical with cochleas described previously. There was a good correlation between the presence of supporting cells and the survival of nerve fibres in the osseous spiral lamina in the corresponding area. In one cochlea, however, the degeneration of only inner hair cells in a small area was associated with complete nerve degeneration in the corresponding sector of the spiral lamina. Giant cilia were frequently seen in the apical turn.

Adult↗
PubMed1990

The fallopian canal and facial nerve in sclerosteosis of the temporal bone: a histopathologic study.

Sclerosteosis is an uncommon subtype of osteopetrosis that is frequently associated with recurrent facial nerve palsy. Because of the need for detailed measurements of the fallopian canal and facial nerve in this disease, a study was carried out using a new method of surface area measurement. The results show narrowing of the fallopian canal and facial nerve in the labyrinthine, distal tympanic and mastoid segments. Maximum surface area loss occurred in the labyrinthine segment for both the canal and nerve. In addition, bony occlusion of the stylomastoid artery was found. From these findings we conclude that ischemia and bony compression are the underlying causes of recurrent facial palsy in this disease. We also conclude that because the labyrinthine segment is the most severely affected, surgical decompression must include this portion of the fallopian canal.

Adult↗
PubMed1990

Menière's symptoms resulting from bilateral otosclerotic occlusion of the endolymphatic duct: an analysis of a causal relationship between otosclerosis and Menière's disease.

An association between otosclerosis and Menière's disease has been proposed on both a clinical and temporal bone histopathologic basis for well over three-quarters of a century. Controversy persists over a causal relationship between these two entities, however, and the underlying pathophysiologic mechanisms relating capsular otosclerosis with Menière's disease remain speculative. The first case of total, bilateral endolymphatic duct occlusion resulting from extensive capsular otosclerosis is presented in a woman manifesting Menière's symptoms. The severe endolymphatic hydrops resulting from otosclerotic endolymphatic duct occlusion is given as histopathologic proof of a causal relationship between these two entities. Analysis of 18 of our own temporal bone cases of extensive capsular otosclerosis without endolymphatic hydrops and review of the literature indicates the uniqueness of such a firm causal relationship in the present case.

Adult↗
PubMed1989

Pharmacokinetics of intra-arterial indomethacin treatment for patent ductus arteriosus.

We present pharmacokinetic data of prolonged, intra-arterial indomethacin treatment (i.e. induction plus maintenance dose) for symptomatic patent ductus arteriosus (sPDA) in 26 ventilated premature infants. sPDA was assessed by two-dimensional and pulsed Doppler echocardiography. Permanent ductal closure occurred in 20 (76%) infants. Plasma levels of indomethacin were 1.18 +/- 0.74; 1.8 +/- 1.0; 1.51 +/- 0.93 and 1.25 +/- 0.98 micrograms/ml (mean +/- SD) at 12, 24, 48 and 72 h after initial dose administration. All except one patient who responded with ductal closure, showed plasma levels above 0.25 microgram/ml throughout the 3 day treatment period and no case of sPDA reopening was noted. Although target concentrations over time were not defined, the data indicate that the maintenance levels measured were within the therapeutic range. A negative correlation was found for plasma drug levels and postnatal age (r = 0.52; P less than 0.01). Volume of drug distribution was 0.23 +/- 0.18 l/kg, total clearance 0.1 +/- 0.11 ml/min and elimination constant 0.06 +/- 0.05 h-1 (mean +/- SD). The great variation in pharmacokinetic data reflects the heterogeneity of the population studied with respect to extracellular fluid space, cardiovascular status, serum protein and other parameters.

Ductus Arteriosus, Patent↗
PubMed1989

Biochemical and morphological effects of human hepatic alkaline phosphatase in a neonate with hypophosphatasia.

Enzyme replacement-therapy for a severely affected premature boy (birthweight: 2,380 g, GA: 36 weeks) with hypophosphatasia was attempted by infusions of purified human hepatic alkaline phosphatase. Treatment (1.2 IU/kg/min) started at age three weeks and was repeated in weekly intervals until age 10 weeks, when the child died. Samples of alkaline phosphatase were diluted with 10 ml of physiological saline and infused over 30 min via an umbilical arterial catheter. No toxic or allergic side effects were observed. Serum alkaline phosphatase activity increased from 3 IU/L before treatment to a maximum level of 195 IU/L with a half-life time between 37 and 62 hours. Urinary excretion of phosphoethanolamine decreased during therapy from a maximal level of 9.5 to 5.5 mumol/mg creatinine (normal: less than 0.4 mumol/mg creatinine). Calcium, phosphorus, parathormone and 1,25-diOH vitamin D levels were within normal range. Sequential radiographic studies showed no improvement of bone mineralization. Bone morphology was studied by light and electron microscopy before treatment and post mortem. The borderline between mineralized and unmineralized matrix was more distinct after treatment and on the electron microscopical level initial spots of mineralization were more frequent between the collagen fibrils compared to the biopsy specimen before treatment. In contrast to previous studies however, only woven and bundle bone structures were studied from the tibial crest, where the lack of osteoblast-like cells upon the newly formed osteoid matrix was prominent.

Alkaline Phosphatase↗
PubMed1989

Diagnosis of peripheral androgen insensitivity in a male infant excretion analysis.

The hypothesis of peripheral androgen insensitivity (AIS) was examined in a boy with congenital growth hormone deficiency associated with micropenis and cryptorchidism by steroid excretion analyses compared with dihydrotestosterone (DHT) receptor analyses of foreskin biopsy homogenate. Urinary T metabolite 3 alpha,17 beta-dihydroxy-5 beta-androstane (3 beta-diol) was below the limit of detection (capillary gas chromatography) at age 1 year, but on several occasions (n = 7) normal basal values were found at age 3 years (patient: 78.9 +/- 25.4 micrograms/24 h, M +/- SD; controls, n = 15: 100.5 +/- 50.2). Normal basal- and hCG-induced excretion was noted for 3 alpha,17 beta-dihydroxy-5 alpha-androstane (3 alpha-diol) at age 1 and 3 years, respectively. Additionally, basal 3 alpha-diol excretion (n = 7) at age 3 years was 66.7 +/- 21.1 micrograms/24 h, M +/- SD; controls (n = 15) 75.8 +/- 50.4. Analysis of urinary androgens might be an alternative, noninvasive procedure for the diagnosis of peripheral AIS.

Androgens↗
PubMed1988

[Plasma thiocyanate determination: a simple method for quantifying the smoking habits of pregnant patients--a preliminary study].

Plasma thiocyanate (SCN) was measured by means of a simple colorimetric method [8] in 328 persons (175 males, 153 females, aged 5-68 years) as part of an ongoing prospective trial on the influence of SCN defined maternal smoking on fetal development. The interassay coefficient of variation for synthetic K thiocyanate solutions was 3.1% (n = 25%); the intrassay coefficient of variation was 1.2% (n = 15). Mean SCN levels were significantly lower in 226 nonsmokers (SCN 41.4 +/- 18.5 mumol/l) than 102 smokers (SCN 81.4 +/- 28.7 mumol/l; p less than 0.01). Of all the variables tested, a direct influence on SCN was found only in the case of diabetes mellitus and haemolytic blood samples (p less than 0.01), whereas age, sex, chronic diseases and nutrition had no effect on SCN. Mean maternal post partum SCN levels (n = 48) were significantly lower in non-smokers (30.2 +/- 11.2) than in smokers (59.3 +/- 23.1). There was a linear relationship between maternal venous plasma and fetal umbilical cord plasma SCN values (r = 0.88; p less than 0.01). Pregnant women had lower SCN levels than non-pregnant women. We conclude that SCN is an easy means of measuring and a reproducible parameter for quantifying smoking behaviour in pregnancy and in the general population.

Adolescent↗
PubMed1988

[Prognostic significance of the onset of infection in newborn infants].

Between September 86 and May 87 we reviewed the case histories of 25 newborns (gestational age: 33-41 weeks, birth weight: 1280-3600 g) with septicaemia proved by positive blood cultures. Two groups are formed: Group A: onset of sepsis within the first 48 hours of life (10 newborns), group B: onset of sepsis after 48 hours of life (15 newborns). No differences in gestational age and birth weight were found between the groups. Amnionitis was found in 8 mothers (80%) of group A, however, we found only 2 (13%) mothers with amnionitis in group B. All patients in group A had signs of the respiratory distress syndrome and their clinical condition was poor. Only the CRP was helpful in the laboratory diagnosis of septicaemia. In group B sepsis was diagnosed in 11 (73%) patients by means of a raised CRP and an increased immature neutrophil count. Only 4 patients of this group showed clinical deterioration. The following bacteria were cultured: Group A: E. coli 4, b-streptococci 3, Klebsiella 3. Group B: Staph, aureus 8, Strept. faecalis 5, Pseudomonas 2. In group A 3 patients died and 3 patients developed meningitis with neurological sequelae. In group B non of the patients died, but 2 patients developed osteomyelitis.

Bacteria↗
PubMed1988

Sympatho-adrenal response to hypoglycaemia in infants.

The response of the sympathoadrenal system to hypoglycaemia of different etiology was studied in seven infants, aged 10-189 days. Five infants had hyperinsulinism secondary to nesidioblastosis or to a beta-cell adenoma of the pancreas, one infant had neonatal sepsis due to staphylococcal infection and one infant congenital growth hormone (HGH) and adrenocorticotropic hormone (ACTH) deficiency. In babies with hyperinsulinism, plasma noradrenaline increased from 0.29 +/- 0.03 to 0.61 +/- 0.09 ng/ml (P less than 0.01), whereas adrenaline increased only in three, but did not change in two babies. Increases in heart rate and blood pressure paralleled these changes. In hypoglycaemia due to congenital sepsis, noradrenaline increased from 0.39 to 1.64 ng/ml and adrenaline from 0.05 to 0.86 ng/ml. This was associated with marked haemodynamic changes. In congenital HGH and ACTH deficiency, the low basal plasma levels of noradrenaline (0.12 ng/ml) and adrenaline (0.01 ng/ml) remained unchanged in response to hypoglycaemia. Heart rate and blood pressure were unaffected. The sympathoadrenal system was activated by hypoglycaemia in all infants except in congenital HGH and ACTH deficiency. In contrast to adults, noradrenaline was the preferentially released catecholamine, suggesting an involvement of noradrenaline in glucose counter regulation in infancy.

Adrenal Glands↗
PubMed1988

A new europium chelate for protein labelling and time-resolved fluorometric applications.

Synthetic procedures are presented for a new chelator that forms stable and highly fluorescent complexes with Eu3+. This chelator, 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid (BCPDA) is synthesized in a high-yield three-step procedure. BCPDA can be covalently incorporated into proteins under relatively mild conditions, and when complexed with Eu3+ forms a fluorescent product that has a lifetime in the range of 0.4 to 0.7 ms. Thus, it is useful for time-resolved fluorescence immunoassay applications.

Animals↗
PubMed1988

Familial pseudohypoaldosteronism.

The clinical course of two siblings with a severe form of pseudohypoaldosteronism was followed over a period of seven and five years respectively. Both children persistently had a high sodium-potassium excretion ratio in the urine, sweat, saliva, and stools as well as high serum concentrations of aldosterone and renin and an increased urinary excretion of tetrahydroaldosterone. Despite sustained treatment with sodium chloride (10-40 mmol/kg/d) and cation exchange resin (sodium polystyrole sulfonate 0.5-2 g/kg/d) they repeatedly developed episodes of salt wasting and hyperkalemia which occurred mainly during uncomplicated respiratory tract infections. Aldosterone receptor characteristics were studied in the cytosol of the rectal mucosa at ages 2.5 years and 6 months respectively. Compared to age matched controls there was a decreased affinity for aldosterone at the low affinity binding site. Among the members of the family, the father and one of his sisters had high concentrations of sodium in the sweat and an increased urinary excretion of tetrahydroaldosterone.

Adult↗
PubMed1988

Non-enzymatic glycation of fetal tissue in diabetic pregnancy. Estimation of the glucitollysine content of umbilical cord extracts.

Non-enzymatic glycation of fetal tissue was studied by determining the glucitollysine content of umbilical cord extracts from twelve infants of diabetic mothers and fourteen infants of healthy, non-diabetic women (controls). The single, glycated amino-acid glycitollysine, which reflects the extent of glycation processes in biological samples, was measured by a standard amino acid ion exchange chromatography followed by reverse phase high pressure liquid chromatography. Infants of diabetic mothers had significantly higher cord glucitollysine levels than infants of control mothers (14.3 + 4.6 vs. 5.5 + 2.1 ng/mg dry tissue; M + SD, p less than 0.001). Moreover, five infants of diabetic mothers with congenital anomalies had strikingly high glucitollysine levels, higher than the mean +4 SD of the controls. We conclude, that non-enzymatic glycation of fetal tissue does occur as a result of an in utero exposure to cumulative glycemia. Major congenital anomalies in diabetic pregnancies are associated with a greater extent of non-enzymatic glycation of umbilical cord tissue.

Adult↗
PubMed1988

Histopathology of the facial nerve after longitudinal temporal bone fracture.

The temporal bone histopathology in a patient who suffered repeated head trauma and a longitudinal temporal bone fracture shows unusual features associated with the facial nerve. In the distal meatal segment, a type of traumatic neuroma was found with disorganized nerve bundles and distinct areas of Schwann's cell proliferation but lacking fibrosis. Periosteal new bone formation in the labyrinthine segment narrows the fallopian canal and protrudes into the nerve, which completely fills the canal. The tympanic and mastoid segments of the nerve show severe degeneration of nerve fibers and an increase in connective tissue between fascicles. An attempted facial nerve decompression did not reach the area of primary pathology in the labyrinthine and meatal segments of the nerve, which could have been exposed by the transtemporal supralabyrinthine approach.

Adult↗
PubMed1987

Endolymphatic pressure in experimental hydrops.

Perilymphatic and endolymphatic pressures were consecutively measured by means of a servomechanical nulling pressure system through the round window and basilar membrane one to 2.5 months after obliteration of the left endolymphatic sac and duct in seven guinea pigs. The position of the pipette was monitored by the simultaneous recording of the direct current potential through the micropipette used for the pressure measurement. (1) The perilymphatic and endolymphatic pressures of the control ears were equal. (2) The histological evaluation showed that the ears operated on had a significantly greater endolymphatic space than the control ears. (3) The endolymphatic pressure of the ear operated on was significantly higher (0.78 +/- 0.32 mm Hg) than that of the perilymph. (4) The endolymphatic direct current potential was equal in both ears.

Animals↗