Magnitude and causes of blindness and low vision in Anambra State of Nigeria (Results of 1992 point prevalence survey)

A survey to determine the prevalence and causes of blindness in Anambra State of Nigeria was conducted. The aim was to provide baseline data for the planning, implementation and evaluation of both the state's and the National Programme for Prevention of Blindness.A multistage cluster random sampling technique was used. The World Health Organization/Prevention of Blindness (WHO/PBL) Eye Examination Record Form was used. The WHOs definitions of blindness and low vision were adopted for the analysis.The prevalence of blindness in the state is estimated to be 0.33%±0.27%. Visual acuity of from 3/60 to less than 6/60 has a prevalence of 0.41%±0.30% while visual acuity of from 6/60 to less than 6/18 has a prevalence of 0.67%±0.39.There are equal numbers of blind males as females, although the prevalence among males is 0.44%±0.26% while among females it is 0.24%±0.15%. Most of the blind are above 50 y of age with prevalence of blindness in this age group being 2.62%±1.31% (3.27%±2.1% for males and 2.02%±1.58% for females).Cataract caused most of the blindness (70.59%), followed by glaucoma (17.65%). Macular degeneration is becoming important (5.88%) while obvious infective causes are rare. Errors of refraction are important public eye health care problems.Methods of tackling the cataract problem (both backlog and incident), and other eye health needs within the primary eye/health care are recommended. The need to extend refraction services to the rural areas is emphasized.     

Serum factors stimulate the motility of human spermatozoa

Motile human sperm were collected from a Percoll gradient and the effects on sperm motility of human serum, various serum fractions, follicular fluid and seminal plasma were assessed. In culture medium alone (RPMI-1640) sperm motility was lost after about 5 h. The addition of male blood serum both enhanced sperm motility and prolonged viability very significantly. Albumin, seminal plasma and follicular fluid all stimulated sperm motility but to a much lesser extent than did blood serum. No difference was noted between male serum or female serum which had been collected during the follicular or luteal phases of hormone-stimulated cycles and which contained high levels of oestradiol. Serum fractions obtained by separation on Sephacryl S-300 column were tested for their ability to enhance sperm motility. The most pronounced effect, much superior to that achieved by the albumin fraction, was obtained by a fraction with a molecular weight of around 200 kD. In conclusion, certain factors in human serum, which are different from albumin, strongly support sperm motility. The high serum concentrations of oestradiol resulting from hormone stimulation for in-vitro fertilization do not invalidate the use of serum from the same patient during sperm preparation, or in the medium used for ovum insemination and culture.     

Extremity bone tumors: evaluation by P-31 MR spectroscopy

High-resolution P-31 MR spectra were obtained in four patients with bone tumors of their distal extremities. In one case the tumor, a Ewing sarcoma of the tibia, was investigated during clinical remission after radiation therapy and chemotherapy. The other three cases - one low-grade chondrosarcoma of the tibial head, one malignant fibrous histiocytoma of the tibia, and one chondroblastoma of the medial femoral condyle - showed clinically active tumor growth, with corresponding increased metabolism as demonstrated by bone scintigraphy. The spectra of the three active tumors indicated a comparably high adenosine triphosphate content, similar to previously published spectra from animal tumors or human tumors implanted into animals. There were also high resonances of inorganic phosphate and low resonances of phosphocreatine; there were definite peaks in the phosphodiester and phosphomonoester regions, indicating the existence of these metabolites in the tumors. Slight but definite changes in the metabolite content were observed in one tumor after chemotherapy. The spectra of the unaffected leg did not show any well-resolved P-31 signals, which is typical for healthy bone. These are the first P-31 MR spectra of human bone tumors measured in patients to our knowledge.     

Phylogenetic, ontogenetic, and pathological aspects of the urine-concentrating mechanism

The urine-concentrating mechanism is one of the most fundamental functions of avian and mammalian kidneys. This particular function of the kidneys developed as a system to accumulate NaCl in birds and as a system to accumulate NaCl and urea in mammals. Based on phylogenetic evidence, the mammalian urine-concentrating mechanism may have evolved as a modification of the renal medulla's NaCl accumulating system that is observed in birds. This qualitative conversion of the urine-concentrating mechanism in the mammalian inner medulla of the kidneys may occur during the neonatal period. Human kidneys have several suboptimal features caused by the neonatal conversion of the urine-concentrating mechanism. The urine-concentrating mechanism is composed of various functional molecules, including water channels, solute transporters, and vasopressin receptors. Abnormalities in water channels aquaporin (AQP)1 and AQP2, as well as in the vasopressin receptor V2R, are known to cause nephrogenic diabetes insipidus. An analysis of the pathological mechanism involved in nephrogenic diabetes insipidus suggests that molecular chaperones may improve the intracellular trafficking of AQP2 and V2R, and, in the near future, such chaperones may become a new clinical tool for treating nephrogenic diabetes insipidus.     

Chloride-dependent intracellular pH regulation via extracellular calcium-sensing receptor in the medullary thick ascending limb of the mouse kidney

The extracellular calcium-sensing receptor (CaSR) located in either luminal or basolateral cell membranes of various types of renal tubules including proximal tubules, Henle's loop and collecting ducts has been thought to play a fundamental role in electrolyte metabolism. To further identify the physiological roles of the CaSR, we examined the effects of Ca(2+) and calcimimetics neomycin (Neo), gentamicin and gadolinium chloride (Gd(3+)) on the intracellular pH (pHi) of in vitro microperfused mouse medullary thick ascending limb (mTAL) cells of Henle's loop, by loading the cells with fluorescent pH indicator 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein and measuring the ratio of fluorescence emission at 530 nm after exciting the dye at 490 and 440 nm. In a steady-state condition in Hepes-buffered solution, the pHi in the mTALs was 7.29 +/- 0.04 (n = 9). A concentration of 200 micromol/l Neo in the basolateral side decreased the pHi after 1 min by -0.13 +/- 0.02 (n = 34, p < 0.0001). The other calcimimetics showed similar effects on pHi, whereas none of these calcimimetics in the lumen affected pHi. Na(+) removal or the inhibition of Na(+) and proton transport with amiloride, bumetanide, or bafilomycin did not eliminate the effect of Neo on pHi. On the other hand, Cl(-) removal clearly eliminated the Neo-induced pHi decrease (-0.06 +/- 0.01 vs -0.00 +/- 0.05 in Cl(-) removal, n = 4, p < 0.003). Thus, we have demonstrated for the first time that the CaSR is involved in the regulation of the pHi in the mTAL and requires Cl(-) to exert its effect.     

Characteristics of the clinical picture of combined injuries of the organ of vision and eye appendages under conditions of peace-time and war injuries

A total of 100 patients with combined injuries of the organ of vision and eye appendages, inflicted in peacetime and under war conditions, were examined. The clinical picture of combined injuries in the wounds inflicted at the battlefield (gunshot and resultant from mine explosions) and of traffic, communal, criminal, and occupational injuries was studied using traditional ophthalmological and common clinical instrumental methods of examination. Common regularities of the traumatic process were revealed in combined injuries: mutual aggravation of injuries to the eye and its appendages, a considerable incidence of bilateral injuries, and simultaneous impacts of several damaging factors. The most unfavorable prognosis as regards visual functions in the group observed was for patients with war injuries, particularly those caused by mine explosions.