Exposing some important barriers to health care access in the rural USA

OBJECTIVES

To review research published before and after the passage of the Patient Protection and Affordable Care Act (2010) examining barriers in seeking or accessing health care in rural populations in the USA.

STUDY DESIGN

This literature review was based on a comprehensive search for all literature researching rural health care provision and access in the USA.

METHODS

Pubmed, Proquest Allied Nursing and Health Literature, National Rural Health Association (NRHA) Resource Center and Google Scholar databases were searched using the Medical Subject Headings (MeSH) 'Rural Health Services' and 'Rural Health.' MeSH subtitle headings used were 'USA,' 'utilization,' 'trends' and 'supply and distribution.' Keywords added to the search parameters were 'access,' 'rural' and 'health care.' Searches in Google Scholar employed the phrases 'health care disparities in the USA,' inequalities in 'health care in the USA,' 'health care in rural USA' and 'access to health care in rural USA.' After eliminating non-relevant articles, 34 articles were included.

RESULTS

Significant differences in health care access between rural and urban areas exist. Reluctance to seek health care in rural areas was based on cultural and financial constraints, often compounded by a scarcity of services, a lack of trained physicians, insufficient public transport, and poor availability of broadband internet services. Rural residents were found to have poorer health, with rural areas having difficulty in attracting and retaining physicians, and maintaining health services on a par with their urban counterparts.

CONCLUSIONS

Rural and urban health care disparities require an ongoing program of reform with the aim to improve the provision of services, promote recruitment, training and career development of rural health care professionals, increase comprehensive health insurance coverage and engage rural residents and healthcare providers in health promotion.

A deficit of detoxification enzymes: pesticide sensitivity and environmental response in the honeybee

The honeybee genome has substantially fewer protein coding genes ( approximately 11 000 genes) than Drosophila melanogaster ( approximately 13 500) and Anopheles gambiae ( approximately 14 000). Some of the most marked differences occur in three superfamilies encoding xenobiotic detoxifying enzymes. Specifically there are only about half as many glutathione-S-transferases (GSTs), cytochrome P450 monooxygenases (P450s) and carboxyl/cholinesterases (CCEs) in the honeybee. This includes 10-fold or greater shortfalls in the numbers of Delta and Epsilon GSTs and CYP4 P450s, members of which clades have been recurrently associated with insecticide resistance in other species. These shortfalls may contribute to the sensitivity of the honeybee to insecticides. On the other hand there are some recent radiations in CYP6, CYP9 and certain CCE clades in A. mellifera that could be associated with the evolution of the hormonal and chemosensory processes underpinning its highly organized eusociality.

Missense mutations in COL8A2, the gene encoding the alpha2 chain of type VIII collagen, cause two forms of corneal endothelial dystrophy

Corneal clarity is maintained by its endothelium, which functions abnormally in the endothelial dystrophies, leading to corneal opacification. This group of conditions includes Fuchs' endothelial dystrophy of the cornea (FECD), one of the commonest indications for corneal transplantation performed in developed countries, posterior polymorphous dystrophy (PPCD) and the congenital hereditary endothelial dystrophies (CHED). A genome-wide search of a three-generation family with early-onset FECD demonstrated significant linkage with D1S2830 (Z(max) = 3.72, theta = 0.0). Refinement of the critical region defined a 6-7 cM interval of chromosome 1p34.3-p32 within which lies the COL8A2 gene. This encodes the 703 amino acid alpha2 chain of type VIII collagen, a short-chain collagen which is a component of endothelial basement membranes and which represented a strong candidate gene. Analysis of its coding sequence defined a missense mutation (gln455lys) within the triple helical domain of the protein in this family. Mutation analysis in patients with FECD and PPCD demonstrated further missense substitutions in familial and sporadic cases of FECD as well as in a single family with PPCD. This is the first description of the molecular basis of any of the corneal endothelial dystrophies or of mutations in type VIII collagen in association with human disease. This suggests that the underlying pathogenesis of FECD and PPCD may be related to disturbance of the role of type VIII collagen in influencing the terminal differentiation of the neural crest derived corneal endothelial cell.

International Nosocomial Infection Control Consortium report, data summary of 50 countries for 2010-2015: Device-associated module

BACKGROUND

We report the results of International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2010-December 2015 in 703 intensive care units (ICUs) in Latin America, Europe, Eastern Mediterranean, Southeast Asia, and Western Pacific.

METHODS

During the 6-year study period, using Centers for Disease Control and Prevention National Healthcare Safety Network (CDC-NHSN) definitions for device-associated health care-associated infection (DA-HAI), we collected prospective data from 861,284 patients hospitalized in INICC hospital ICUs for an aggregate of 3,506,562 days.

RESULTS

Although device use in INICC ICUs was similar to that reported from CDC-NHSN ICUs, DA-HAI rates were higher in the INICC ICUs: in the INICC medical-surgical ICUs, the pooled rate of central line-associated bloodstream infection, 4.1 per 1,000 central line-days, was nearly 5-fold higher than the 0.8 per 1,000 central line-days reported from comparable US ICUs, the overall rate of ventilator-associated pneumonia was also higher, 13.1 versus 0.9 per 1,000 ventilator-days, as was the rate of catheter-associated urinary tract infection, 5.07 versus 1.7 per 1,000 catheter-days. From blood cultures samples, frequencies of resistance of Pseudomonas isolates to amikacin (29.87% vs 10%) and to imipenem (44.3% vs 26.1%), and of Klebsiella pneumoniae isolates to ceftazidime (73.2% vs 28.8%) and to imipenem (43.27% vs 12.8%) were also higher in the INICC ICUs compared with CDC-NHSN ICUs.

CONCLUSIONS

Although DA-HAIs in INICC ICU patients continue to be higher than the rates reported in CDC-NSHN ICUs representing the developed world, we have observed a significant trend toward the reduction of DA-HAI rates in INICC ICUs as shown in each international report. It is INICC's main goal to continue facilitating education, training, and basic and cost-effective tools and resources, such as standardized forms and an online platform, to tackle this problem effectively and systematically.

Insulin- and mitogen-activated protein kinase-mediated phosphorylation and activation of peroxisome proliferator-activated receptor gamma

Peroxisome proliferator-activated receptor (PPAR) gamma plays an important role in adipocyte differentiation and the regulation of adipocyte gene expression. Insulin also serves to promote adipogenesis. We report that insulin and a PPARgamma ligand (thiazolidinedione (TZD)) stimulate in a synergistic manner the expression of an adipocyte-specific gene (aP2) in rat adipocytes and 3T3-L1 cells. Potential cross-talk between insulin signaling and PPARgamma was studied in Chinese hamster ovary cells expressing insulin receptors (CHO.T), PPARgamma, and reporter genes. Both TZD and insulin independently stimulated PPARgamma-mediated transactivation of aP2 promoter-luciferase reporter genes; both agents combined resulted in a synergistic effect. Co-transfection of CHO.T cells with dominant-negative mitogen-activated protein (MAP) kinase-kinase (MKK1) abrogated both insulin- and TZD-mediated activation of PPARgamma; transactivation was markedly increased in cells co-transfected with constitutively active MKK1. Both insulin and constitutively active MKK1 also stimulated 32P incorporation into PPARgamma in vivo. The conclusions are: 1) Insulin synergizes with a PPARgamma ligand and can activate the receptor in a ligand-independent fashion. 2) PPARgamma is phosphorylated in vivo by insulin stimulation or activation of the MAP kinase pathway. 3) MAP kinase is an important mediator of cross-talk between insulin signal transduction pathways and PPARgamma function.

Hypoxia-targeted siRNA delivery

Altered vasculature and the resultant chaotic tumor blood flow lead to the appearance in fast-growing tumors of regions with gradients of oxygen tension and acute hypoxia (less than 1.4% oxygen). Due to its roles in tumorigenesis and resistance to therapy, hypoxia represents a problem in cancer therapy. Insufficient delivery of therapeutic agents to the hypoxic regions in solid tumors is recognized as one of the causes of resistance to therapy. This led to the development of hypoxia imaging agents, and the use of hypoxia-activated anticancer prodrugs. Here we show the first example of the hypoxia-induced siRNA uptake and silencing using a nanocarrier consisting of polyethyleneglycol 2000, azobenzene, polyethyleneimine (PEI)(1.8 kDa), and 1,2-dioleyl-sn-glycero-3-phosphoethanolamine (DOPE) units (the nanocarrier is referred to as PAPD), where azobenzene imparts hypoxia sensitivity and specificity. We report hypoxia-activated green fluorescent protein (GFP) silencing in vitro and its downregulation in GFP-expressing tumors after intravenous administration. The proposed nanoformulation represents a novel tumor-environment-responsive modality for cancer targeting and siRNA delivery.

Guanylyl cyclase C is a selective marker for metastatic colorectal tumors in human extraintestinal tissues

Guanylyl cyclase C (GCC) has been detected only in intestinal mucosa and colon carcinoma cells of placental mammals. However, this receptor has been identified in several tissues in marsupials, and its expression has been suggested in tissues other than intestine in placental mammals. Selective expression of GCC by colorectal tumor cells in extraintestinal tissues would permit this receptor to be employed as a selective marker for metastatic disease. Thus, expression of GCC was examined in human tissues and tumors, correlating receptor function with detection by PCR. GCC was detected by ligand binding and catalytic activation in normal intestine and primary and metastatic colorectal tumors, but not in extraintestinal tissues or tumors. Similarly, PCR yielded GCC-specific amplification products with specimens from normal intestine and primary and metastatic colorectal tumors, but not from extraintestinal tissues or tumors. Northern blot analysis employing GCC-specific probes revealed an approximately 4-kb transcript, corresponding to recombinant GCC, in normal intestine and primary and metastatic colorectal tumors, but not in extraintestinal tissues. Thus, GCC is selectively expressed in intestine and colorectal tumors in humans and appears to be a relatively specific marker for metastatic cancer cells in normal tissues. Indeed, PCR of GCC detected tumor cells in blood from some patients with Dukes B colorectal cancer and all patients examined with Dukes C and D colorectal cancer, but not in that from normal subjects or patients with Dukes A colon carcinoma or other nonmalignant intestinal pathologies.

The ocular features of the mucopolysaccharidoses

AIMS

The mucopolysaccharidoses (MPS) are a heterogeneous group of rare disorders characterised by accumulation of glycosaminoglycans within multiple organ systems. This study aimed to determine the prevalence and severity of ocular complications in patients with MPS.

METHODS

Clinical ophthalmic features and electrodiagnostic results of 50 patients with a diagnosis of MPS were retrospectively reviewed.

RESULTS

A total of 79% of MPS IH patients had a visual acuity of less than 6/12 equivalent in their better eye, compared to 44% of MPS IH/S and 25% of MPS VI patients. In total, 16% of MPS IH and 25% of MPS IH/S had severe corneal opacification, compared to 38% of MPS VI patients. 16% of MPS IH patients had optic atrophy; 21% of MPS VI patients had mild disc swelling, 29% had markedly swollen discs, and 14% had optic atrophy. One patient with MPS IH, one with MPS IH/S and six with MPS VI had ocular hypertension. One MPS VI patient had glaucoma that required topical therapy. Nine patients with MPS IH had electrodiagnostic evidence of retinopathy, as did one MPS VI patient.

CONCLUSIONS

Ocular complications causing significant reduction in vision are common in MPS. The majority of MPS I and MPS VI patients have corneal opacification, which can lead to difficulties in diagnosis and monitoring of glaucoma, optic disc changes, and retinopathy.

Polymorphism in the gene encoding the apical membrane antigen-1 (AMA-1) of Plasmodium falciparum. X. Asembo Bay Cohort Project

We have investigated the genetic diversity of the gene encoding the apical membrane antigen-1 (AMA-1) in natural populations of Plasmodium falciparum from western Kenya and compared it with parasite populations from other geographic regions. A total of 28 complete sequences from Kenya, Thailand, India, and Venezuela field isolates were obtained. The genetic polymorphism is not evenly distributed across the gene, which is in agreement with the pattern reported in earlier studies. The alleles from Kenya exhibit 20 and 30% more polymorphism than that found in Southeast Asia and Venezuelan alleles, respectively. Based on the gene genealogies derived from sequencing data, no evidence for allele families was found. We have found evidence supporting limited gene flow between the parasite populations, specifically, between the Southeast Asian and Venezuelan isolates; however, no alleles could be linked to a specific geographic region. This study reveals that positive natural selection is an important factor in the maintenance of genetic diversity for AMA-1. We did not find conclusive evidence indicating intragenic recombination is important in the generation of the AMA-1 allelic diversity. The study provides information on the genetic diversity of the AMA-1 gene that would be useful in vaccine development and testing, as well as in assessing factors that are involved in the generation and maintenance of the genetic diversity in P. falciparum.

Prevention of cytotoxic effects of arsenic by short-term dietary supplementation with selenium in mice in vivo

Interaction between selenium and arsenic has been used to protect against the genotoxic effects of sodium arsenite through dietary intervention by an equivalent amount (1/10 LD50) of sodium selenite. The two salts were administered by gavaging to laboratory bred Swiss albino mice sequentially and in combination. Cytogenetic endpoints, including chromosomal aberrations (CA) and damaged cells (DC) were recorded 24 h after exposure from chromosome spreads in bone marrow cells. Administration of sodium selenite 1 h before sodium arsenite reduced the clastogenic effects of the latter significantly. The protection was less when the salts were given together and negative when arsenite was given before selenite. Histological changes were recorded. Such reduction of arsenic toxicity through dietary intervention by selenium is of significance in protecting against the widespread toxicity observed in human populations exposed to arsenic through drinking water from contaminated deep tubewells in West Bengal and Bangladesh.

Selective inhibition of mitochondrial respiration and glycolysis in human leukaemic leucocytes by methylglyoxal

The effect of methylglyoxal on the oxygen consumption of mitochondria of both normal and leukaemic leucocytes was tested by using different respiratory substrates and complex specific artificial electron donors and inhibitors. The results indicate that methylglyoxal strongly inhibits mitochondrial respiration in leukaemic leucocytes, whereas, at a much higher concentration, methylglyoxal fails to inhibit mitochondrial respiration in normal leucocytes. Methylglyoxal strongly inhibits ADP-stimulated alpha-oxoglutarate and malate plus NAD+-dependent respiration, whereas, at a higher concentration, methylglyoxal fails to inhibit succinate and alpha-glycerophosphate-dependent respiration. Methylglyoxal also fails to inhibit respiration which is initiated by duroquinone and cannot inhibit oxygen consumption when the N,N,N', N'-tetramethyl-p-phenylenediamine by-pass is used. NADH oxidation by sub-mitochondrial particles of leukaemic leucocytes is also inhibited by methylglyoxal. Lactaldehyde, a catabolite of methylglyoxal, can exert a protective effect on the inhibition of leukaemic leucocyte mitochondrial respiration by methylglyoxal. Methylglyoxal also inhibits l-lactic acid formation by intact leukaemic leucocytes and critically reduces the ATP level of these cells, whereas methylglyoxal has no effect on normal leucocytes. We conclude that methylglyoxal inhibits glycolysis and the electron flow through mitochondrial complex I of leukaemic leucocytes. This is strikingly similar to our previous studies on mitochondrial respiration, glycolysis and ATP levels in Ehrlich ascites carcinoma cells [Ray, Dutta, Halder and Ray (1994) Biochem. J. 303, 69-72; Halder, Ray and Ray (1993) Int. J. Cancer 54, 443-449], which strongly suggests that the inhibition of electron flow through complex I of the mitochondrial respiratory chain and inhibition of glycolysis by methylglyoxal may be common characteristics of all malignant cells.

Cholecystokinin A and B receptors are differentially expressed in normal pancreas and pancreatic adenocarcinoma

Cholecystokinin (CCK) plays an important role in pancreatic carcinogenesis. While human CCK-A and -B receptors have been fully characterized, their relative roles in human pancreatic adenocarcinoma remain unclear. Thus, expression of CCK-A and -B receptors in normal human pancreas, pancreatic adenocarcinomas, and other human extrapancreatic tissues and malignancies was examined, using reverse transcription followed by the polymerase chain reaction (RT-PCR). mRNA isolated from 15 normal pancreas specimens, 22 pancreatic adenocarcinomas, and 58 extrapancreatic tissues and tumors was subjected to RT-PCR using primers specific for human CCK-A and -B receptors. Expression of CCK-B receptors was detected in all tissues arising from pancreas and in most extrapancreatic tissues and tumors. In contrast, CCK-A receptors exhibited a more selective pattern of expression in gall bladder, intestine, brain, ovary, spleen, and thymus. Of significance, CCK-A receptors were expressed selectively in all pancreatic adenocarcinomas, but not in any normal pancreas specimens. In situ hybridization, using receptor-specific riboprobes, localized CCK-A receptor expression to ductal cells, the presumed origin of most human pancreatic adenocarcinomas. Southern blot analysis revealed no evidence of CCK-A receptor gene amplification or rearrangement in pancreatic adenocarcinomas. Because of its selective expression, the CCK-A receptor may serve as selective biomarker for pancreatic adenocarcinoma.

Preparation and Evaluation of Silymarin β-cyclodextrin Molecular Inclusion Complexes

Silymarin is a hepatoprotective agent, having poor water solubility and oral absorption of about 23 – 47%, leading to low bioavailability of the drug. The aim of the present study is to improve the solubility and dissolution rate and in turn the hepatoprotective activity of the drug, by formulating its inclusion complex with beta (β)-cyclodextrin, using different methods. The phase solubility analysis indicates the formation of 1:1 molar inclusion complex of the drug with beta cyclodextrin. Apparent stability constant for Silymarin (K_c) was 722 K^-1 with β-cyclodextrin complex. The inclusion complexes were prepared by four different methods, namely, physical mixing, kneading, co-precipitation, and solvent evaporation. The prepared complexes were characterized using differential scanning colorimetry, scanning electron microscopy, and x-ray diffractometry. The inclusion complex prepared by the co-precipitation methods exhibits an overall best result, with respect to the formulation of sustained release formulations.

Pharmacological and dietary antioxidant therapies for chronic obstructive pulmonary disease

The progression and exacerbations of chronic obstructive pulmonary disease (COPD) are intimately associated with tobacco smoke/biomass fuel-induced oxidative and aldehyde/carbonyl stress. Alterations in redox signaling proinflammatory kinases and transcription factors, steroid resistance, unfolded protein response, mucus hypersecretion, extracellular matrix remodeling, autophagy/apoptosis, epigenetic changes, cellular senescence/aging, endothelial dysfunction, autoimmunity, and skeletal muscle dysfunction are some of the pathological hallmarks of COPD. In light of the above it would be prudent to target systemic and local oxidative stress with agents that can modulate the antioxidants/ redox system or by boosting the endogenous levels of antioxidants for the treatment and management of COPD. Identification of various antioxidant agents, such as thiol molecules (glutathione and mucolytic drugs, such as N-acetyl-L-cysteine, N-acystelyn, erdosteine, fudosteine, ergothioneine, and carbocysteine lysine salt), dietary natural product-derived polyphenols and other compounds (curcumin, resveratrol, green tea catechins, quercetin sulforaphane, lycopene, acai, alpha-lipoic acid, tocotrienols, and apocynin) have made it possible to modulate various biochemical aspects of COPD. Various researches and clinical trials have revealed that these antioxidants can detoxify free radicals and oxidants, control expression of redox and glutathione biosynthesis genes, chromatin remodeling, and ultimately inflammatory gene expression. In addition, modulation of cigarette smoke-induced oxidative stress and related cellular changes have also been reported to be effected by synthetic molecules. This includes specific spin traps like α-phenyl-N-tert-butyl nitrone, a catalytic antioxidant (ECSOD mimetic), porphyrins (AEOL 10150 and AEOL 10113), and a superoxide dismutase mimetic M40419, lipid peroxidation and protein carbonylation blockers/inhibitors, such as edaravone and lazaroids/tirilazad, myeloperoxidase inhibitors, as well as specialized pro-resolving mediators/inflammatory resolving lipid mediators, omega-3 fatty acids, vitamin D, and hydrogen sulfide. According to various studies it appears that the administration of multiple antioxidants could be a more effective mode used in the treatment of COPD. In this review, various pharmacological and dietary approaches to enhance lung antioxidant levels and beneficial effects of antioxidant therapeutics in treating or intervening the progression of COPD have been discussed.

Enhanced nonlinear optical properties of graphene oxide–silver nanocomposites measured by Z-scan technique

Enhanced (by ∼2.8) nonlinear optical property of GO–Ag nanocomposite has been reported by Z-scan technique at a visible wavelength of 532 nm. The synthesized GO–Ag nanocomposite is also displaying significant optical limiting effect.

Advances in the management of congenital and infantile cataract

Congenital and infantile cataracts produce deprivation amblyopia and can thus cause lifelong visual impairment. Successful management is dependent on early diagnosis and referral for surgery when indicated. Accurate optical rehabilitation and postoperative supervision are essential.The timing of surgery and its relationship to the duration of deprivation is important. Unilateral congenital cataract surgery within 6 weeks of birth produces the best outcomes. The equivalent 'latent' period for bilateral visual deprivation may be longer at around 10 weeks. Visual deprivation has a significant impact on the development of fixation stability. Major form deprivation, even after early surgery, leads to nystagmus. This is mostly manifest latent nystagmus (MLN). The latent period for fixation stability may be as short as 3 weeks. Preoperative congenital nystagmus (CN) can convert to more benign MLN after surgery. Infantile IOL implantation is becoming increasingly accepted. A satisfactory long-term refractive result requires that allowance be made for childhood axial growth and myopic shift. In a series of 25 infants (33 eyes) implanted before 12 months of age, the mean myopic shift at 12 months was 4.83 D. This increased to 5.3 D in infants implanted before 10 weeks. The initial desired refractive outcome following IOL implantation is thus hypermetropia, with the degree dependent on the age of the child. Glaucoma or ocular hypertension is a common complication following paediatric cataract surgery. Microphthalmia and surgery in early infancy are risk factors. Tonometry results may be influenced by the increased corneal thickness seen in aphakic and pseudophakic children. The long-term prognosis of eyes with aphakic glaucoma is not necessarily poor but intraocular pressure control may require three or more medications. Surgical intervention appears to be necessary in over a quarter of eyes. Posterior capsule opacification (PCO) is common in infants undergoing primary lens implantation. Primary capsulotomy and anterior vitrectomy reduce the risk of PCO. In the absence of anterior vitrectomy, primary posterior capsulotomy does not prevent visual axis opacification. Further developments will continue to be driven by clinical research. The prevention of capsule opacification and cellular proliferation may in future be achieved by the use of devices to specifically target epithelial cells at surgery.

Enhanced UV detection by transparent graphene oxide/ZnO composite thin films

Highly transparent graphene oxide–ZnO composite films synthesized by simple chemical method inhibit electron–hole recombination, modulate carrier transport and enhance UV detection capability.

Use of guanylyl cyclase C for detecting micrometastases in lymph nodes of patients with colon cancer

INTRODUCTION

Guanylyl cyclase C appears to be expressed only in colorectal cancer cells in extraintestinal tissues. Thus, guanylyl cyclase C may be useful as a marker to detect colorectal cancer micrometastases not detectable by histopathology in lymph nodes of patients.

METHODS

Twelve patients with colon adenocarcinoma, Dukes Stages A through C2, and one patient with a tubulovillous adenoma were included in this study. Forty-two lymph nodes were collected from fresh surgical specimens, and each was examined by histopathology and reverse transcription followed by polymerase chain reaction using guanylyl cyclase C-specific primers. Histopathology identified colon cancer cells in 6 of 16 lymph nodes from five Dukes Stage C patients but not in lymph nodes from the patient with a tubulovillous adenoma, the Dukes Stage A patient, or six Dukes Stage B patients. Reverse transcription followed by polymerase chain reaction using guanylyl cyclase C-specific primers was performed on all 42 lymph nodes.

RESULTS

Guanylyl cyclase C messenger RNA was not detected by reverse transcription followed by polymerase chain reaction in lymph nodes from the patient with the tubulovillous adenoma or the patient with Dukes Stage A colon carcinoma. Seven lymph nodes from Dukes Stage C patients revealed guanylyl cyclase C messenger RNA including six lymph nodes containing histopathologically confirmed metastases. Of significance, guanylyl cyclase C messenger RNA was detected in 6 of 21 lymph nodes from Dukes Stage B patients. Indeed, clinical staging of two patients could be upgraded from B to C using reverse transcription followed by polymerase chain reaction and guanylyl cyclase C-specific primers.

CONCLUSION

Reverse transcription followed by polymerase chain reaction using guanylyl cyclase C-specific primers might be useful to more accurately assess micrometastases in lymph nodes of colorectal cancer patients undergoing disease staging.

Increased apoptosis in rat brain after rapid eye movement sleep loss

Rapid eye movement (REM) sleep loss impairs several physiological, behavioral and cellular processes; however, the mechanism of action was unknown. To understand the effects of REM sleep deprivation on neuronal damage and apoptosis, studies were conducted using multiple apoptosis markers in control and experimental rat brain neurons located in areas either related to or unrelated to REM sleep regulation. Furthermore, the effects of REM sleep deprivation were also studied on neuronal cytoskeletal proteins, actin and tubulin. It was observed that after REM sleep deprivation a significantly increased number of neurons in the rat brain were positive to apoptotic markers, which however, tended to recover after the rats were allowed to undergo REM sleep; the control rats were not affected. Further, it was also observed that REM sleep deprivation decreased amounts of actin and tubulin in neurons confirming our previous reports of changes in neuronal size and shape after such deprivation. These findings suggest that one of the possible functions of REM sleep is to protect neurons from damage and apoptosis.

Accuracy of intraocular lens power calculation in paediatric cataract surgery

AIMS

To determine the accuracy of intraocular lens (IOL) power calculation in a group of pseudophakic children.

METHODS

A retrospective analysis of biometric and refractive data was performed on 52 eyes of 40 infants and children, who successfully underwent cataract extraction and IOL implantation. The following parameters were included: age at the time of surgery, keratometry, axial length, estimated refraction, and the power of IOL implanted. The postoperative refractive outcome was taken as the spherical equivalent of the refraction at 3 months after surgery. The prediction error was taken as the absolute difference between the estimated and actual postoperative refraction. The data were analysed to assess the effects of age at the time of surgery, keratometry, and axial length on the accuracy of calculation of IOL power.

RESULTS

For the overall group the mean and median prediction errors were 1.40 D and 0.84 D (SD 1.60). The mean and median prediction errors in eyes with axial lengths > or =20 mm were 1.07 D and 0.71 D (SD 0.98) and in eyes <20 mm were 2.63 D and 2.61 D (SD 2.65). The mean and median prediction errors in eyes in children aged > or =36 months were 1.06 D and 0.68 D (SD 1.02) and in children aged <36 months was 2.56 D and 2.29 D (SD 2.50). The differences between the prediction errors for both axial length and age were statistically significant (p<0.05).

CONCLUSIONS

For the overall group IOL power calculation is satisfactory. In eyes with axial lengths less than 20 mm and in children less than 36 months of age larger errors can arise. This study demonstrates the need for an IOL formula specifically designed for paediatric use.

Fructose and hormone levels in semen: their correlations with sperm counts and motility

Levels of fructose, growth hormone (GH), prolactin (HPr), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and 5alpha-dihydrotestosterone (DHT) were determined in semen. The samples were obtained from patients attending an infertility clinic and separated into four groups according to the number of spermatozoa. Levels of HPr, LH, and FSH showed significant positive correlations with sperm counts. Significant differences in fructose and hormone levels were found between various groups. Expressed as concentrations of hormones or fructose per milliliter of semen, none of the hormones showed a significant negative correlation with sperm motility whereas fructose showed a significant negative correlation. Expressed as amounts per ejaculate of semen, only prolactin showed a significant positive correlation with sperm motility. The significance of these findings is discussed.

The role of nitric oxide in the process of implantation in rats

Nitric oxide (NO) plays an important role in cell signalling in many physiological systems, including reproduction. During pregnancy, oestrogen modulates uterine NO generation, and NO may play an intermediary role in the oestrogen-mediated effects on the uterus. Since oestrogen is actively involved in inducing endometrial receptivity to support the process of implantation, the role of NO in the process of implantation in rats was investigated. N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase (NOS), was administered in utero with or without sodium nitroprusside (SNP), a generator of NO, on different days during the preimplantation phase of gestation. The status of gestation in respect of implantation failure, endometrial receptivity and embryo development were assessed. L-NAME was administered at various doses (2-5 mg per uterine horn) and on different days of pregnancy (days 2-6 of pregnancy) to optimize the pregnancy terminating dose (absence of implantation site on day 8 of pregnancy) and the effective day of treatment. L-NAME led to failure of implantation when administered at 2.5 mg per uterine horn on day 3 of pregnancy. The characteristic preimplantation permeability changes in the uterus were significantly attenuated and embryo growth was retarded. The L-NAME-mediated effects were significantly reversed when SNP (100 micrograms) was co-administered with L-NAME. These findings suggest a role for NO in the process of implantation. The possible mechanism by which inhibition of the NO-NOS system may interfere with implantation is discussed.

Neuropeptide Y alters monoamine turnover in the rat brain

The effects of intracerebroventricular administration of neuropeptide Y (NPY) on central monoamine turnover were studied in rats treated with alpha-methyl-p-tyrosine (alpha-MPT). NPY decreased noradrenaline turnover in the brainstem, hypothalamus, midbrain and hippocampus. Dopamine turnover was decreased in the brainstem and striatum of NPY-treated rats. Although alpha-MPT did not seem to affect the turnover of serotonin, the concentration of this amine after the administration of NPY was higher in the brainstem, hypothalamus and striatum. Our results suggest that NPY may play a role in the modulation of monoamine turnover in the central nervous system.