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H Pau

Publications and source records attributed to H Pau.

At least 19 recordsLinked to original sources
PubMed1992

The significance of brown coloration with regard to lens nuclear hardness in the case of extracapsular lens extraction.

Prior to extracapsular cataract extraction, it is useful to have an indication of the nuclear hardness by means of slit-lamp microscopy. Using a fine conical probe and a miniature dynamometer, the resistance to penetration (hardness) of different colored lenses and different forms of 'senile' cataract was measured exactly. In cataracts with gray, brown, or black nucleus and sometimes a clear cortex or deep supranuclear, subcapsular or intumescent cortical opacities, distinct hardening of the nucleus was found, which reached values 3-4 times higher than in clear lenses of 80 year olds. Increasing pathological brown or black coloration of the lens nucleus is related to maximum hardness; on the other hand, maximum hardening was not restricted to brown or black coloration. In some cases we only found brownish or grayish coloration in the lens nucleus that had reached maximum hardness. We found the consistency of clear nuclei of deep supranuclear and subcapsular cortical cataracts to be the same values as those of clear lenses with clear nuclei of the same age.

Aged↗
PubMed1991

The increasing sclerosis of the human lens with age and its relevance to accommodation and presbyopia.

By means of a fine conical probe and a miniature dynamometer, the resistance to penetration of different lens layers was measured. In clear human lenses the power of resistance of the lens nucleus increases with age, mostly due to the "hardening" of the nucleus. A distinct hardening of the nucleus as opposed to the cortex has been found to occur in lenses as young as 20 years of age. This "firmness" of the lens nucleus, occurring between the ages of 20 and 60 years, coincides with the decrease in accommodation range and the onset of presbyopia.

Accommodation, Ocular↗
PubMed1990

Glutathione levels in human lens: regional distribution in different forms of cataract.

The content of glutathione is high in the anterior lens cortex (plus epithelium) and the posterior lens cortex, whereas it is substantially lower in the lens nucleus. A decrease of glutathione in the lens cortex does not occur with lenses from adults up to the highest age. The glutathione content is highest in the cortex of clear fresh lenses and shows a decrease with deep supranuclear cataract, primary nuclear cataract (cataracta brunescens nigra) and clear lenses post-mortem (approximately 20 hr). The subcapsular cataract, especially with additional secondary nuclear cataract, with cataracta matura or intumescens, shows a rapid and pronounced progressive decrease in the glutathione content.

Age Factors↗
PubMed1990

Changes in the energy metabolism of cultured lens epithelial cells in comparison with the fresh lens.

Energy metabolism of bovine cultured lens epithelial cells (CLEC) was compared to that of fresh bovine lens. CLEC contained high levels of ATP (44 nmol mg protein-1) and creatine phosphate (13 nmol mg protein-1). An ATP/ADP ratio of ten and a creatine phosphate/creatine ratio of two indicated the cells were in a well-energized state. ATP concentration in fresh epithelium was comparable to that of CLEC; however in the anterior cortex it was tenfold lower. In contrast to fresh lenses, CLEC were able to oxidize glucose, lactate and palmitic acid. Lactate was oxidized at the highest rate. In CLEC, 42% of the ATP generated by catabolizing glucose resulted from oxidative phosphorylation. Glucose (5 mM) was degraded to lactate and CO2 at a 2:1 ratio. The hexose monophosphate pathway accounted for two thirds of the CO2 produced. In the fresh whole bovine lens palmitate was not oxidized and lactate was oxidized to a lesser degree than in CLEC. Only one-tenth of the ATP generated by glucose catabolism in the fresh whole lens was derived from oxidative phosphorylation. This was also the case for a preparation of fresh epithelium, maintained in air and 100% oxygen, demonstrating that the preferential glycolytic catabolism of glucose in lens is not caused by limited oxygen diffusion. In the fresh bovine lens the epithelium accounted for one third of the glucose catabolism of the whole lens, even though it had only about 0.1% of its protein mass. In fresh human lenses, conversion of glucose into lactate was even more pronounced--the lactate/CO2 ratio was 73:1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1990

Appearance of alpha-smooth muscle actin in human eye lens cells of anterior capsular cataract and in cultured bovine lens-forming cells.

Using light and electron-microscopic immunolocalization techniques, and gel electrophoresis combined with immunoblotting, we have examined the expression of cytoskeletal proteins in normal human fetal, child and adult lenses, in human anterior capsular cataract and in bovine lens cells in vivo and in vitro. In this report, we focus our observations on the pattern of actin-isoform expression during normal and pathological situations in vivo and culture conditions. We have noted that cells of developing and mature human lenses as well as bovine lens cells in situ contain only beta- and gamma-actins. In contrast, alpha-smooth muscle (alpha-sm) actin, an isoform typical of smooth muscle differentiation, was demonstrated in bovine lens cells at different times of culture. Moreover, the multilayered cells observed in the subcapsular zone of human anterior capsular cataract were characterized by the presence of alpha-sm actin. Thus, extensive changes in actin-isoform expression take place in lens cells growing in culture and may also occur during cataractogenesis. The biological meaning of the appearance of a marker of myoid differentiation in the ectodermally derived lens-forming cells is discussed.

Actins↗
PubMed1990

Nucleotide levels in human and bovine lenses: a study on regional postmortem changes.

Regional lens adenine nucleotide levels were determined in human and bovine lenses using sensitive HPLC techniques. In adult lenses of both species adenine nucleotide levels were highest in the anterior cortex (plus epithelium and capsule) followed by the posterior cortex (plus capsule) and lowest in the nucleus. With increasing lens age ATP level remained steady in the anterior cortex (plus epithelium and capsule) and nucleus, while those in the posterior cortex showed a tendency toward decrease. In both species, human as well as bovine, adenine nucleotide levels of the anterior cortex (plus epithelium and capsule) underwent early postmortem changes. Thus, immediate postmortem sampling as well as regional determinations are a must for detailed studies of lens nucleotide metabolism.

Adenine Nucleotides↗
PubMed1989

Lesion and regeneration of the anterior and posterior lens capsule and cortex in rabbits Nd:YAG laser.

With a mode-locked Nd:YAG laser set at various energy levels, anterior and posterior capsular and cortical lesions were produced in the lens of rabbits. Biomicroscopic and Scheimpflug examinations showed the anterior lesion to be healing in a whitish scar that was restricted to the area of the original lesion. Histology and transmission electron microscopy (TEM) demonstrated the proliferation of epithelial cells that produced a new, continuous, basement membrane-like capsule. In the area of the lesion collagenous material, myofibroblast-like cells and macrophages were found. Laser-induced lesions in the posterior lens capsule and lens protein resulted in damage to the capsule and grey opacity of the lenticular proteins, which remained unchanged for 6 weeks. Neither inflammatory nor epithelial cells appeared within the locally damaged lens. Macrophages migrated from the vitreous into the lesion; they were observed either in intercellular clefts or within a lens fibre, almost completely taking up their cross section.

Animals↗
PubMed1989

Nucleotide levels in human lens: regional distribution in different forms of senile cataract.

Sensitive high-performance liquid chromatography methods were employed to assess regional distribution of adenine, guanosine and uridine nucleotides in clear and cataractous human eye lenses. According to slit-lamp examination, three forms of senile cataract were distinguished: (1) supranuclear or deep cortical cataract (typical senile cataract), (2) primary nuclear cataract (cataracta brunescens) and (3) subcapsular cortical cataract associated either with a supranuclear (3a) or a secondary nuclear cataract (3b). Except for AMP, which was highest in the nuclear fraction, all other nucleotides (ATP, ADP, GTP, and UTP) were predominantly located in the anterior cortex (plus epithelium) of clear as well as cataractous lenses, that is, ATP levels in the nucleus amounted to 20% of those found in the anterior cortex (plus epithelium); ATP levels in the posterior cortex were about 60% of those in the anterior cortex (plus epithelium). Significant differences in the absolute regional nucleotide level existed between the different forms of cataract. Highest ATP levels were found in the anterior cortex (plus epithelium) of clear lenses and deep or supranuclear cortical cataract. The ATP level was slightly diminished in primary nuclear cataract and in supranuclear cortical cataract when associated with an early subcapsular cortical cataract. ATP levels were depressed to less than 30% in the anterior cortex (plus epithelium) of lenses with a subcapsular cortical cataract when associated with either an early secondary nuclear or a mature cataract. Furthermore, the ATP/ADP ratio was decreased in this form of senile cataract. The decrease in lens nucleotide level did not correlate with increased age. These data suggest that decreases in regional ATP level are a secondary event and do not appear to be causally involved in the genesis of the 'cataracta senilis'.

Adenosine Diphosphate↗
PubMed1989

Regional water content of clear and cataractous human lenses.

The present study evaluates the regional water content of clear and cataractous human lenses. In order to determine the lens water, a freeze-drying technique was used which leaves behind only a very small amount of residual humidity. The effectiveness of freeze-drying was demonstrated in experiments with animal eye lenses (rat, pig, bovine). The results obtained revealed that, like in other mammalian lenses, the human lens cortex exhibits a significantly higher overall water content than the nucleus. This pattern was found in clear lenses as well as in lenses with early 'senile' cataracts. Subcapsulary cataracts present a unique feature as in these lenses the cortical water content is enhanced while the fresh lens weight is significantly reduced. Observations of postmortem human eye lenses indicate that regional differences in water content are greatly abolished 24-48 h after death.

Aged↗
PubMed1989

Organization of collagen and other extracellular material in anterior capsular cataract.

Capsular cataract takes the form of a white-grey opacity appearing under the anterior lens capsule (anterior subcapsular cataract). The capsule is wrinkled through the action of myofibroblast-like cells developed from the anterior lenticular epithelium. The myofibroblast-like cells also produce collagen that takes on a dysplastic appearance. Collagenous microfibrils accumulate to form fibre-like aggregations. These aggregations represent an abnormal collagen density (collagen condensation or attraction) in comparison to normal collagenous fibrils and fibres. Within the anterior capsular cataract 4 topological regions may be distinguished: Cell regions (1), stratification regions (2), aggregation regions (3), and intermediate regions (4). It is postulated that these regions represent different stages in the maturation and degradation of collagen, in the absence of phagocytic elements.

Cataract↗
PubMed1989

[Biological parameters of so-called "senile cataracts"].

With advancing age the weight of the lens of the eye tends to increase in both human beings and animals; simultaneously, the percentage of enzymes in the entire lens decreases. These phenomena can be explained by the fact that the enzymes are mostly located in the epithelium and superficial nucleate fibers of the lens. In addition, the central part of the lens, which steadily increases its volume and percentage of the weight of the whole lens over a lifetime, has relatively few or no enzymes at all. In the superficial layers the enzyme content adenosine triphosphate (ATP) and glutathione remains high even in old age, and the cation pump K+ greater than Na+ is still intact. This fact is also true in deep supranuclear cataracts and primary nuclear cataracts. In subcapsular cataracts, however, the ATP and glutathione content decreases rapidly and the cation pump is defect.

Adenosine Triphosphate↗
PubMed1988

[Clinical aspects and experimental findings in so-called senile cataracts. Determination of status].

In this article the authors review the present state of our knowledge concerning senile cataract. Clinical observations, frequencies and prognosis, biochemical and biometrical results, etiology and pathogenesis as well as aspects of cataract epidemiology are presented. The available information indicates that the term "senile cataract" comprises a multiplicity of morphologically different types of opacities all characterized by unique properties. With respect to clinical relevance and for research purposes it is obvious and essential to replace the term "senile cataract" with more precise definitions appropriate to the type and localization of the opacity.

Aged↗
PubMed1988

[A table of senile forms of cataract. Clinical picture, prognosis, biochemistry and etiology].

The three important types of age-related senile cataract, namely deep supranuclear cortical cataract, superficial subcapsular cortical cataract (sometimes associated with secondary nuclear cataract), and primary nuclear cataract, are arranged in a table which may be used for quick reference with regard to clinical features - slit lamp findings, age at onset of opacification, rate of progression, and related biochemistry (e.g., ATP content, glutathione content, and the cation pump (K+ greater than Na+] - as well as etiological features. The significance of the table is illustrated on the basis of an important example from the literature ("Sunlight and Human Cataracts").

Adenosine Triphosphate↗