Biomedical subjects

S Sperling

Publications and source records attributed to S Sperling.

At least 19 recordsLinked to original sources

PubMed2003

Molar incisor hypomineralisation in a group of children and adolescents living in Dresden (Germany).

AIM: This was to determine the prevalence of Molar Incisor Hypomineralisation (MIH) and to evaluate possible causes of these enamel defects. METHODS: The study group consisted of 2,408 10-17 year old children born during 1985-1992 and living in Dresden (Germany). Enamel defects were recorded using the modified DDE index. Children with enamel defects and their parents were invited for a re-examination to record the medical history of the children during the first 3 years of life; these children were matched by age with other children with apparently normal first molars (control group). RESULTS: 135 (5.6%) of the children had demarcated opacities in at least one first molar, i.e. MIH. A significantly higher prevalence of MIH was seen in children born between 1989 and 1991 compared with those born before and after that period (p<0.01). The number of children returning for the medical history questionnaire was low, 31 out of 135 responded (test group). Although there were no significant differences between the test and control groups in terms of peri and neonatal complications or other health problems, the low return precluded any definitive interpretation. CONCLUSION: The overall prevalence of MIH in this study was low by comparison with other previous epidemiological reports.

Adolescent↗

PubMed2001

Triple A syndrome is caused by mutations in AAAS, a new WD-repeat protein gene.

The triple A syndrome (MIM 231550) is a rare autosomal recessive disorder characterized by adrenal insufficiency, achalasia and alacrima. The frequent association with a variety of neurological features may result in a severely disabling disease. We previously mapped the syndrome to a 6 cM interval on chromosome 12q13 and have now refined the critical region to 0 cM between KRT8 and D12S1651. Overlapping bacterial artificial chromosome (BAC) sequences of a high resolution BAC/P1-derived artificial chromosome (PAC) contig were screened for gene content and a novel gene encoding a 546 amino acid polypeptide was identified. In nine triple A syndrome patients eight different homozygous and compound heterozygous mutations were found in this gene, most of them leading to a truncated protein suggesting loss of function. RNA blotting experiments revealed marked expression in neuroendocrine and gastrointestinal structures, which are predominantly affected in triple A syndrome, supporting the hypothesis that mutations in this triple A syndrome gene (AAAS) are responsible for the disease. The predicted protein belongs to the family of WD repeat-containing proteins which exhibit a high degree of functional diversity including regulation of signal transduction, RNA processing and transcription.

Abnormalities, Multiple↗

PubMed1987

The swelling pressure of the human corneal stroma as determined by a new method.

The swelling pressure of 115 human corneas was determined using a modified electronic balance modified to simultaneously record the swelling force and the thickness of the stroma. The swelling force was found to follow a straight-line dependence on the stromal thickness when plotted in a double logarithmic scale, which means that the swelling pressure of each cornea could be expressed by a power fit of the form SP = aTb, where SP is swelling pressure, T stromal thickness, and a and b are constants of the cornea. In 45 control corneas swollen in 0.9% NaCl, pH 7.4, 0.01 M Hepes buffer, the mean value (+/- S.D.) of 'a' and 'b' were 7.09 mmHg mm-1 (+/- 2.96) and -3.48 (+/- 0.20), respectively. This corresponded to a mean swelling pressure of 84.0 mmHg at a standard stromal thickness of 0.5 mm. In paired experiments, the swelling pressure was found to be influenced insignificantly (P greater than 0.05) by a number of conditions, including lowering the pH to 4.0, increasing the temperature to 37 degrees C, and increasing the NaCl concentration to 9%. A significant correlation was found between the swelling pressure and the dry weight of the specimen (P less than 0.05), indicating a considerable biological variation of the swelling pressure. It is shown, that this variation may explain the normal variation in human corneal thickness in vivo.

Cornea↗

PubMed1986

Evaluation of the endothelium of human donor corneas by induced dilation of intercellular spaces and trypan blue.

The endothelium of 30 pairs of human cadaver corneas was stained by trypan blue and the intercellular spaces were visualized by induced dilation prior to corneal culture. Trypan blue staining and induced dilation of intercellular spaces by 0.9% and 0.45% NaCl were found to be atraumatic. Only a fraction of damaged cells were stained by trypan blue. Endothelial cell losses in culture did not correlate with the number of trypan-blue stained cells, the post-mortem time, or donor age.

Adult↗

PubMed1983

Electron microscopy of cultured human corneas. Osmotic hydration and the use of a dextran fraction (dextran T 500) in organ culture.

Human corneas were studied by means of electron microscopy after culture at 31 degrees C for two to 20 days in a medium containing 8% dextran T 500. Dextran T 500, a strong osmotic agent, was included in the culture medium to prevent excessive swelling of the cornea. In order to exclude the possibility that the observed effects were the result of osmotic changes during fixation, in each experiment, fixatives with different osmolalities were used (430, 574, 727, and 812 mOsm). After 8, 16, and 20 days of culture, vacuoles appeared that were filled with dextran; the cytoplasm was completely filled with these vacuoles. The vacuolization was not limited to the endothelium, but was also observed in stromal keratocytes and to a limited extent in the epithelium. It was concluded that the monolayer of endothelium was still intact after 20 days of culture in medium containing 8% dextran T 500, and, secondly, that the dextran might have been taken up by endocytosis. Whether or not the uptake of dextran has a long-term toxic effect on the corneal cells remains to be elucidated.

Adolescent↗

PubMed1983

Ultrastructure of cryopreserved, functioning human corneal endothelium.

The endothelium was studied by light- and electronmicroscopy in a cryopreserved cornea transplanted to a woman with herpetic keratitis and removed after 18 months because of wound dehiscence and epithelialization of the anterior chamber. The graft was perfectly transparent and of normal thickness. Light microscopy revealed the existence of a continuous layer of endothelial cells, showing pronounced pleomorphism when examined in flat preparation, with large multinuclear cells between smaller more normal looking mononuclear cells. The heterogeneous cell pattern resembled that observable in vitro after freezing and 24 h of culture. The cells therefore are not considered to be in a steady state. The ultrastructure of the majority of the cells was similar to that of non-cryopreserved endothelium. Cell cohesion took place by tight junctions, the intercellular spaces were of normal width. Ultrastructurally there was, however, a cellular heterogeneity, due to the occurrence of light cells with few organelles, but always with intact cell membranes. These cells probably represent slow death of endothelial cells, demonstrated by falling cell density during the 18 months between grafting and examination. We conclude from this study that cells surviving the freezing can maintain a clinically normal endothelial function for 18 months by forming a continuous quasistatic monolayer of tightly bound living cells.

Adult↗

PubMed1982

Post-operative thickness and endothelial cell density in cultivated, cryopreserved human corneal grafts.

Seventeen corneas obtained 2-72 h post mortem, from donors aged 17-78 years, were cultivated for 24 h, cryopreserved, thawed, cultivated for another 24 h and grafted. One year post-operatively 12 of the 17 grafts were clear. In 10 of these 12 cases the visual acuity was greater than or equal to 0.33. One primary graft failure occurred, while 4 primarily clear grafts became cloudy due to glaucoma (2), phthisis bulbi (1) and herpetic reinfection (1). One year after the transplantations the central thickness of the clear grafts was 0.51 mm, and the endothelial cell density was 1028 cells/mm2, corresponding to 32% of the cell density before cryopreservation. This endothelial cell loss was not correlated to donor age or to the time between the death of the donor and the primary cultivation.

Adolescent↗

PubMed1982

Human corneal endothelial cell density after an in vitro imitation of elevated intraocular pressure.

Normal human cadaver corneas were mounted in test chambers 10-52 h post mortem, regenerated for 24 h in a modified tissue culture medium, and exposed to a laboratory imitation of elevated intraocular pressure. The endothelial cell density was determined before application of the pressure and after 24 h of culture without a pressure difference between the anterior and the posterior corneal surfaces. Pressure differences of 160 and 80 mmHg maintained for 8 and 72 h did not lead to decreased endothelial cell densities.

Cell Count↗

PubMed1981

Thymidine incorporation by human corneal endothelium during organ culture.

Nine corneas from 5 human adult donors were obtained 11 to 31 h post mortem. In 4 corneas the endothelium was wounded by freezing and in 1 cornea by mechanical means. Care was taken to minimize endothelial damage in the remaining 4 corneas. The corneas were incubated at 31 degrees C for 6 days in a tissue culture medium containing 3H thymidine. Autoradiographs were made of the flat preparations of the endothelium. All corneas contained radioactive endothelial cell nuclei, with the highest concentration of labelled nuclei being in the wound areas. The greatest number of labelled cells was found in the cornea from the youngest donor, 19 years of age, but thymidine uptake also occurred in the oldest cornea, 89-years-old, which additionally had signs of endothelial dystrophy.

Adult↗

PubMed1981

Decontamination of cadaver corneas.

Bacterial contamination of human corneas, in vivo and post mortem, was investigated. Bacterial samples were obtained by pressing small concave agar plates directly against the corneas. More colony forming units (C.F.U.) occurred in samples obtained from patients in general anesthesia than in samples obtained from healthy persons in local anaesthesia. The largest number of C.F.U. occurred post mortem. The number of C.F.U. obtained from cadaver corneas was not correlated to post mortem time. Rinsing with water removed 86% of the C.F.U. on cadaver corneas. Rinsing with water for 30 sec followed by 2 min treatment with 0.5% polyvinylpyrrolidone-iodine (PVP-I) and repeated rinsing removed 98% of the C.F.U. Epithelial or stromal lesions were not found after 2 min of exposure to 0.5% PVP-I.

Bacteria↗

PubMed1981

A simple apparatus for controlled rate corneal freezing II.

A corneal freezer without electrical or mechanical function is described. Cooling is achieved by partial immersion of the freezing unit in liquid nitrogen. The cooling rate is controlled by the heat content in the unit and the facility for heat removal from the unit. Corneas are frozen in aluminum vials. Corneas are thawed in less than 30 sec without risk of over heating, when the vials are placed on the metal core of another freezing unit at room temperature.

Animals↗

PubMed1981

Cryopreservation of human cadaver corneas regenerated at 31 degrees C in a modified tissue culture medium.

Human corneas were obtained 2-82 h post mortem, cultured for 20-28 h, in a modified tissue culture medium, frozen at a controlled rate, and thawed rapidly. The thawed corneas were subjected to 20-28 h of additional culture. Immediately after thawing, a mean endothelial cell damage of 11% was indicated by trypane blue staining. The mean endothelial cell loss during the subsequent culture was 34%. This cell loss was not related to post mortem time, to donor age, to cell loss during the primary culture, or to endothelial cell density.

Cadaver↗

PubMed1981

Fresh and cultured corneal grafts compared by post-operative thickness and endothelial cell density.

Thirty-nine corneas were removed within 6 h post mortem and stored in a moist chamber at 4 degrees C before grafting. The mean donor age was 33 years and the average time between death and grafting was 11 h. Thirty cadaver corneas were selected after trypane blue staining and cultured at 31 degrees C for 24 h before grafting. The mean donor age was 61 years and the mean time between death and culture was 18 h. During the first 10 postoperative days fresh grafts were thinner than cultured grafts. One year after the transplantation the two groups did not differ significantly in regard to the clinical result, corneal thickness, or endothelial cell loss. This indicates that corneas from old donors with extended post mortem time can be used for transplantation after individual evaluation and corneal culture.

Adult↗

PubMed1980

The surface coat on human corneal endothelium.

Scanning electron microscopy of human cadaver corneas revealed a selective binding of ruthenium red-osmium tetroxide to some substance coating the posterior endothelial surface. A coating material was not found on autolyzed cells, on denuded areas of the membrane of Descemet, or on the anterior surface of endothelial cells. Partial digestion of the coating material by urokinase and trypsin suggests the presence of at least three different structural or chemical elements.

Cadaver↗

PubMed1980

Endothelial morphology related to disease activity in human corneas.

Twenty normal and four groups of pathological corneas with the diagnoses aphakia, macula after herpetic keratitis. Fuchs' endothelial dystrophy and graft rejection were stained with trypane blue and alizarin red. The morphology of the endothelium was described in terms of cell density, coefficient of variation for cell area, percentage of hexagonal cells, percentage of joint meetings of more than three cells, nuclei per cell and nuclear shape. The groups of aphakia, keratitis, Fuchs' dystrophy and graft rejection were considered to represent increasing degrees of endothelial disease activity at the time of evaluation. The only parameter showing consistent variation with disease activity was the percentage of joint meetings of more than three cells.

Adolescent↗

PubMed1980

Endothelial cell density in donor corneas.

In 68 pairs of donor corneas the endothelial cells were visualized by provoked swelling of the cell borders in isotonic saline. In cornea from donors below 50 years of age numerical cell density was correlated to age. This was not the case in corneas from older donors. The cell densities in paired corneas were correlated. The cell density in the second cornea of a pair was found to be within x +/- 10.97% (+/-1.98SD) of the first cornea. The precision of this estimate could only be improved insignificantly by correction for age, sex, mean cell density or variation of the mean.

Adolescent↗

PubMed1979

Human corneal endothelium in organ culture. The influence of temperature and medium of incubation.

Forty-four human corneas from patients between 21 and 86 years were incubated in Eagle's minimum essential medium with Earle's salts 10--46 h post mortem. The influence of incubation temperature and composition of the medium on endothelial survival was evaluated. Whole corneas were stained by alizarine red. Recent cell loss was indicated by morphological alterations in the endothelial pattern. After 20--28 h of incubation minimum cell loss was found at 31 degrees C when 8% Dextrane-250 and 20% serum or 8% Dextrane-500 and 10% serum was added to the medium.

Adult↗

PubMed1979

Toxicity of dimethylsulfoxide (DMSO) to human corneal endothelium in vitro.

Human cadaver corneas were obtained 10--12 h after clinical death, incubated in organ culture for 20--28 h and exposed 2, 4, 6, 8, 6, 4, and 2% DMSO successively for 10 min at each concentration. Endothelial cell damage was recognized by morphological alterations during reformation of a coherent cell sheat after expulsion of damaged cells. DMSO was found to cause latent cell damage at 31 degrees C. No cell damage was found at 4 degrees C when DMSO was dissolved in minimum essential medium (Eagle) plus Dextran or when DMSO was dissolved in human albumin plus sucrose. DMSO was found to be toxic at 4 degrees C in pure serum and in Dulbecco's medium.

Adolescent↗