Mechanistic In Vitro Dissection of the Inhibition of Amyloid Fibrillation by n-Acetylneuraminic Acid: Plausible Implication in Therapeutics for Neurodegenerative Disorders

A variety of neurodegenerative disorders including Parkinson's disease are due to fibrillation in amyloidogenic proteins. The development of therapeutics for these disorders is a topic of extensive research as effective treatments are still unavailable. The present study establishes that n-acetylneuraminic acid (Neu5ac) inhibits the amyloid fibrillation of hen egg-white lysozyme (HEWL) and α-synuclein (SYN), as observed using various biophysical techniques and cellular assays. Neu5ac inhibits the amyloid formation in both proteins, as suggested from the reduction in the ThT fluorescence and remnant structures in transmission electron microscopy micrographs observed in its presence. In HEWL fibrillation, Neu5ac decreases the hydrophobicity and resists the transition of the α-helix to a β-sheet, as observed by an ANS binding assay, circular dichroism (CD) spectra, and Fourier transform infrared measurements, respectively. Neu5ac stabilizes the states that facilitate the amyloid formation in HEWL and SYN, as demonstrated by an enhanced intrinsic fluorescence in its presence, which is further confirmed by an increase in T_m obtained from differential scanning calorimetry thermograms and an increase in the near-UV CD signal for HEWL with Neu5ac. However, the increase in stability is not a manifestation of Neu5ac binding to amyloid facilitating (partially folded or native) states of both proteins, as verified by isothermal titration calorimetry and fluorescence binding measurements. Besides, Neu5ac also attenuates the cytotoxicity of amyloid fibrils, as evaluated by a cell toxicity assay. These findings provide mechanistic insights into the Neu5ac action against amyloid fibrillation and may establish it as a plausible inhibitor molecule against neurodegenerative disorders.

HIV associated thrombotic microangiopathy

Thrombotic microangiopathy (TMA) is a known complication of HIV infection. Endothelial cell injury appears to be the primary event causing platelet activation and deposition in the microvasculature. Direct cytopathic roles of HIV as well as other factors such as malignancy, drugs, and infectious agents have been implicated in the pathogenesis of HIV-TMA. Although the the majority of patients present in a more advanced stage of HIV disease, TMA can be the initial presenting symptom of HIV infection. Clinical features are those of idiopathic TMA, and the diagnosis should be suspected in any patient with new onset thrombocytopenia and microangiopathic haemolytic anaemia. Therapy with plasma exchange or infusion appears to be efficacious. A rapid diagnosis and institution of plasmapheresis is crucial for a favourable outcome. The long term prognosis of HIV-TMA is unfavourable and may depend on the stage of HIV infection. The recent data after the use of highly active retroviral treatment, however, are unavailable and current prognosis is therefore uncertain.

Lipids in biliary lithogenesis

Serum and biliary lipoproteins, total cholesterol (Tc) and triglycerides (TG) were measured in patients with gallstones and in those without gallstones. Serum and biliary LDLc, TG and Tc were significantly higher (P < 0.001) in cases having gall stones than those without stones while HDLc were low (P < 0.001) in those with stones. No difference was found in very low density lipoproteins (VLDLc) in the two groups. Present data showed that there is a statistically significant correlation of serum and biliary lipoproteins specifically LDLc and HDLc (r = +.67 and r = +.56). This report shows that serum HDLc (67.42%) and LDLc (70.28%) play a more critical role in comparison to total cholesterol (59.43%) and triglyceride (57.15%) levels in the formation of gallstone.

Gender perspectives and quality of care in underdeveloped countries: disease, gender and contextuality

There is indisputable evidence that health indices for women are far worse than those for men, yet women have limited access to health resources. Numerous reasons have been cited for the poor health of women, and include legal constraints to owning property, the lack of participation in the planning process, preferential treatment for boys, and social values, norms and customs. Most of the research on women while adequately documenting these facts, fails to contextualize them in a social, economic and political setting which is often responsible for the problems in the first place. This serious shortcoming negates the efficacy of the well-intentioned and well-meaning solutions in redressing the gender balance. Unless one examines the structural factors which actually cause disease, both in men and women in underdeveloped countries, solutions will be ineffective. The paper also highlights the important fact that there are many more similarities between men and women of the same social class than is appreciated, similarities which are possibly greater than those between the same gender across different social classes.

Short-term IgM and IgG antibody responses to hepatitis E virus infection

53 adult patients with acute hepatitis caused by hepatitis E virus were identified by the presence of IgM antibody to hepatitis E virus, and followed for 12 months to evaluate the kinetics of anti-HEV antibodies. All but 1 female Kuwaiti patient were expatriate workers from the Indian subcontinent, temporarily working in Kuwait. Follow-up samples obtained at 1, 3, 6 and 12 months were evaluated for IgM and IgG antibodies to hepatitis E virus. IgM-class antibodies to hepatitis E virus were detectable in 12/27 (44%) patients at 1 months, in 0/26 at 3 months, in 0/8 at 6 months and 0/6 at 12 months. IgG antibodies to hepatitis E virus were detectable in 46/47 (98%) at onset, 26/27 (96%) at 1 month, in 26/29 (90%) at 3 months, 16/16 (100%) at 6 months and 8/8 (100%) at 12 months of follow-up. This study suggests that IgM antibodies to hepatitis E virus decline rapidly after an acute infection but IgG antibodies to hepatitis E virus persists for at least 1 year in many patients.

Detection of embryologic ventral pancreatic parenchyma with endoscopic ultrasound

BACKGROUND

The prevalence of detecting the embryologic ventral pancreas (ventral anlage) with endoscopic ultrasound (EUS) is unknown.

PURPOSE

To determine the frequency of, and factors associated with, EUS findings consistent with the ventral anlage.

METHODS

One hundred patients undergoing upper gastrointestinal EUS for any indication were prospectively evaluated for the presence of a focal, hypoechoic area in the pancreatic head using a radial scanning echoendoscope. Multiple clinical and EUS variables were tested against the ability to detect the ventral anlage.

RESULTS

The overall detection rate of the ventral anlage was 59%. The ventral anlage was detected in 75% of patients undergoing EUS for nonpancreatic indications, compared to 40% of patients undergoing EUS to evaluate suspected pancreatic disease (p< 0.001). EUS detected the ventral anlage in 72% of patients with a normal EUS-appearing pancreatic head, compared to 29% of patients who had abnormal pancreatic head parenchyma (mass or chronic pancreatitis) on EUS (p < 0.001). Multivariate analysis revealed the only variable associated with detecting the ventral anlage was abnormal pancreatic head parenchyma on EUS.

CONCLUSION

The ventral anlage is frequently detected during pancreatic EUS, with a significantly lower rate of detection in patients with EUS findings of a pancreatic head mass or diffuse chronic pancreatitis.

Planning in the health sector: for whom, by whom?

To state that there are vested interests in health planning is to state the obvious. One can identify numerous actors ranging from international agencies, government officials, pharmaceutical companies, health personnel and community and citizen's groups which would like to stake a claim on the direction and nature of planning and implementing health policy. We argue that the role of specific actors can only be seen in the broader social, economic and ideological framework which, consequently, determines the working of the model of health care. Probably the most important factor influencing health planning is the influence of international donors, governments and agencies. The present ideological tilt towards the market, privatization, less government and more liberalization, has had important repercussions on health planning and delivery. Furthermore, the debt crisis, and the stabilization and structural adjustment programmes being followed by a very large number of underdeveloped countries, are transforming health systems. Essentially, vested interests in health planning within countries, need to be seen in the light of recent ideological and economic changes, and international relations of aid, power and domination.

Control of poliomyelitis in Kuwait

The use of oral poliovirus vaccine (OPV) in the early 1960s marked the beginning of the State's effort in controlling poliomyelitis in Kuwait. During the next two decades, despite the vaccine's availability and use, the disease continued to cause disability and death. However, with the massive and sustained use of the trivalent OPV since 1963G and the introduction of neonatal supplementary immunization with monovalent type 1 (MOPV) in 1976G along with strengthening of the surveillance activities against poliomyelitis, the incidence of the paralytic disease began declining and by the mid-eighties it disappeared altogether. With no cases of paralytic poliomylelitis reported in Kuwait since 1986G, the disease is largely controlled. The epidemiology of poliomyelitis in Kuwait has been examined here in retrospect. The paper profiles about 3 1/2 decades (1958G to 1992G) of efforts that led to this impressive virtual elimination of poliomyelitis. In order to maintain this status and eventually achieve the goal of eradication without the rare occurrence of vaccine-associated paralysis, it is, in our opinion, necessary to adopt an approach of combined vaccination with the inactivated polio vaccine (IPV), preferably in the neonatal age, followed by OPV. Simultaneously, monitoring the presence and circulation of wild poliovirus in the environment and continuous surveillance should be carried out for timely intervention.

Biochemical alterations in the levels of DNA, RNA and protein in discrete areas of rat brain following Nuvacron toxicity

The levels of DNA, RNA and Protein were estimated in cerebral hemisphere, cerebellum and brain stem of male albino rats with Nuvacron (0, 0, dimethyl-0-1 methyl 3-methylamino-3-oxe-1-propenyl phosphate) 4 mg/kg body weight intraperitoneally (i.p.) daily for 10 days. The daily i.p. dose of Nuvacron depleted the level of DNA and protein in all brain regions. Increased level of RNA was observed in cerebral hemisphere, cerebellum and brain stem.

Poverty and disease: need for structural change

In underdeveloped countries, more than 70% of the population suffers from infectious and communicable diseases. These diseases are transmitted with the help of poor water, sanitation, housing, etc. Further, education and nutrition also affect the vulnerability of the individual. All these factors responsible for disease, are themselves dependent on income--the lower the income, the lower education and nutritional status, and the poorer quality the water, and housing. An increase in the absolute income for some, and a redistribution of income for all, are necessary to cure the ills of society. It is possible to increase the real income of individuals by giving them hand-outs or dealing with the problems of their 'basic needs'. However, these approaches do not take into account the underlying factors responsible for disease, and are severely limited in scope. The elite in a country, who, to a great extent, determine the role of the State and of the government, are only willing to give a certain amount of charity, and nothing more. They will, clearly never give to the poor, so much that their own (relative and absolute) position is threatened. The only way possible is through a government which works for the majority of the people, rather than for a small elite.

Significance of blood lactate levels in critically ill patients with liver disease

Lactic acidosis unrelated to tissue hypoxia has been described in patients with liver disease. This raises questions regarding the utility of the arterial lactate level as an indicator of tissue hypoperfusion in critically ill patients with hepatic dysfunction. The incidence of hyperlactatemia in a group of critically ill patients with liver disease and its association with clinical indicators of circulatory shock as well as hospital mortality were examined. The medical records of all patients admitted to the medical intensive care unit of Detroit Receiving Hospital between July 1, 1984, and June 30, 1985, with parenchymal liver disease and a total bilirubin level of more than 2 mg/dl were reviewed. Patients were excluded if lactate was not assayed. The severity of liver disease was assessed by Child's classification. Shock was defined as a systolic blood pressure of less than 90 mm Hg and at least two of the following: urine output of less than 20 ml/hour, evidence of decreased skin perfusion, or acutely altered mentation. These criteria were met in 35 patients; three patients had two medical intensive care unit admissions separated by more than one week. There were two patients in Child's class A, three in class B, and 30 in class C. Shock was identified in 27 of the 38 medical intensive care unit admissions. In the group with shock, the maximal lactate level ranged from 1.2 to 30 mM (mean, 9.6). The lactate level was significantly lower (p less than 0.0005) in the group without shock, ranging from 0.6 to 2.0 mM (mean, 1.3). The mean bilirubin level was significantly higher in the group without shock (16.7 mg/dl) than in the group with shock (8.5 mg/dl). A maximal arterial lactate concentration of more than 2.2 mM was significantly associated with hospital mortality. Thus, lactic acidosis in critically ill patients with liver disease is associated with clinical evidence of shock and with increased hospital mortality.

Undergraduate medical education in underdeveloped countries: the case of Pakistan

The type of medical education of a country is closely linked with its system of health care. Any health care system, with its own peculiarities, requires a certain type of doctor who can function effectively in the given environment. The same is the case with underdeveloped capitalist countries, such as Pakistan, where a skewed, elitist, curative model of health care exists. In Pakistan, where the literacy levels in the native tongue are very low, medicine is taught in English, and nearly all prescribed textbooks are written in and for the West. Conditions specific to Pakistan, such as the degree of cheating in exams, the time lost due to closure, and the level of debate concerning the medical system may find their parallels in other UDCs. Since it is the social and economic forces, which, in the final analysis, determine the system of health care and medical education, one cannot expect any significant improvement within the existing class structure. Only in a country where the masses have control over the production and distribution of resources, can the systems of health care and medical education be brought in line with the real needs of the community and of the country.

Why medical students will not practice in rural areas: evidence from a survey

A survey of medical students was held in order to determine the reasons why they were not willing to set up practice in rural areas after graduation. The reasons they gave were quite typical: lack of facilities, lack of opportunities for themselves and their family, poor income, etc. We also discovered that not many were acquainted with rural health conditions and a very great percentage wanted to go to the West for specialisation. We have tried to set their responses in light of the socio-economic and political system prevalent in a typical capitalist UDC. The conclusion that we have reached is that it is the class system in these societies which has determined the responses of the students, and it is the main factor which causes a dearth of medical manpower in rural areas.

Measles and age of vaccination

Measles is responsible for high morbidity and mortality in children particularly in developing countries. Infants, found by analytical studies to constitute a high risk group, are usually not covered by current vaccination programmes. In Kuwait in the epidemic years during the period 1976-1982, the incidence of measles in infants under one year was found to be more than five times that in the population over one year of age, ranging between 758 and 992 per 100000 live births. During this period as many as one fifth of the total cases (13.3-21.7%) and about one-third of the total deaths (35%) occurred in infants. The mean fatality rate for infants under one year was 3.3 while for the population one year and above it was 1.4. As the immunity derived from the mother declines markedly a large majority of children over six months of age become susceptible to measles. There is a strong case for lowering the age of vaccination against measles to protect the infants, at least in the developing countries, and to control and eventually eradicate the disease.

Observations on haemodynamic effects of mexiletine

The haemodynamic effects of intravenous mexiletine have been studied in 16 patients with valvular heart disease without clinical evidence of heart failure. A bolus injection of 150 mg administered to 6 of the 16 patients resulted in a mean plasma concentration above the therapeutic range for at least 5 minutes after the drug was given. A small but significant rise in the mean pulmonary artery pressure occurred. In 10 patients, the effects of intravenous mexiletine were compared with those of intravenous saline in a double blind trial. No significant difference was found in the haemodynamic effects, though both saline and mexiletine produced a small rise in the mean pulmonary artery pressure. Mexiletine when administered to patients without heart failure in doses known to be clinically effective did not have important adverse haemodynamic effects.

Hemodynamic effects of arteriovenous fistula and bovine graft fistula used for hemodialysis

This study shows that arteriovenous fistulas created for vascular access to hemodialysis result in an increase in cardiac output and pulse rate, and a decrease in the total peripheral resistance. These changes are severe with bovine graft fistula; physicians should be aware of this potentially dangerous hemodynamic change in these patients.

The effect of Kö 1173, a new anticonvulsant agent on experimental cardiac arrhythmias

1. The effects of the intravenous injection of Kö 1173, a new anticonvulsant drug, phenytoin and procainamide were studied on three types of cardiac arrhythmia in dogs.2. Ventricular ectopic beats produced by intravenous injection of adrenaline in anaesthetized dogs respired with halothane were abolished by Kö 1173, 0.6 +/- 0.1 mg/kg, phenytoin, 1.1 +/- 0.3 mg/kg and procainamide, 4.1 +/- 1.8 mg/kg.3. Ventricular tachycardia was produced in anaesthetized dogs by the intravenous injection of ouabain and the three drugs infused intravenously at 0.2 (mg/kg)/min until sinus rhythm returned. Kö 1173 was effective in 8 out of 9 dogs after a mean dose of 1.3 +/- 0.3 mg/kg; phenytoin in all 3 dogs after 2.7 +/- 0.6 mg/kg and procainamide in the 3 dogs tested after 16.6 +/- 1.3 mg/kg.4. The intravenous injection of Kö 1173, 8.0 mg/kg, greatly reduced the number of ventricular ectopic beats occurring in conscious dogs 18-44 h after ligation of the anterior descending branch of the left coronary artery, with a resultant increase in the number of sinus beats. Phenytoin, 8.0 mg/kg, had a similar effect but procainamide was much less effective.5. These results indicate that Kö 1173 is effective in abolishing experimental cardiac arrhythmias and suggest that its effects should be studied in patients.

Comparison of the effects of isoprenaline, orciprenaline, salbutamol and isoetharine on the cardiovascular system of anaesthetized dogs

1. The intravenous injection of isoprenaline, orciprenaline, salbutamol and isoetharine increased heart rate in anaesthetized dogs. Log dose-response curves obtained with a series of doses of salbutamol and isoetharine were flatter than those for isoprenaline and orciprenaline. The order of activity of the drugs in increasing heart rate was isoprenaline, orciprenaline, and salbutamol=isoetharine.2. The injection into the external iliac artery of isoprenaline, orciprenaline, salbutamol and isoetharine produced dose dependent increases in femoral blood flow. Log dose-response curves for all drugs were parallel. The order of activity of the drugs was isoprenaline, salbutamol=isoetharine and orciprenaline.3. Salbutamol and isoetharine were less active than orciprenaline in increasing heart rate but more active in increasing femoral blood flow.4. These observations indicate that salbutamol and isoetharine have a greater effect on beta(2) than on beta(1)-adrenoceptors in the cardiovascular system.

Effects of lignocaine and propranolol on experimental cardiac arrhythmias

1. The effects of intravenous injection of lignocaine and propranolol were studied in dogs.2. Ventricular ectopic beats produced by intravenous injection of adrenaline in anaesthetized dogs respired with halothane were abolished in four out of six dogs by lignocaine. Propranolol was effective in all three dogs tested.3. Intravenous infusion of lignocaine at (0.2 and 1.0 mg/kg)/min to total doses of 3.0 +/- 1.0 and 2.2 +/- 0.5 mg/kg, respectively, abolished the ventricular tachycardia produced in anaesthetized dogs by ouabain. A similar effect was produced by infusion of propranolol at (0.2 mg/kg)/min to a total dose of 1.9 +/- 0.4 mg/kg. Intravenous injection of single doses of lignocaine (4.0-8.0 mg/kg) also abolished the arrhythmia.4. The frequency of the ventricular ectopic beats occurring in conscious dogs 20-44 h after ligation of the anterior descending branch of the left coronary artery was reduced, with an increase in the number of sinus beats, after intravenous injection of lignocaine (8.0 mg/kg). Larger doses produced excitement. Propranolol (4.0 mg/kg) had a greater effect than the same dose of lignocaine but after 8.0 mg/kg, three of the four dogs died.5. Propranolol was more effective than lignocaine in abolishing the three different types of arrhythmia.6. Dose-response curves showed that lignocaine was more active in abolishing the ouabain induced arrhythmia than the halothane-adrenaline arrhythmia and was least active on the arrhythmia caused by ligation of the coronary artery.