Electroosmosis modulated transient blood flow in curved microvessels: Study of a mathematical model.

The flow through curved microvessels has more realistic applications in physiological transport phenomena especially in blood flow through capillary and microvessels. Motivated by the biomicrofluidics applications, a mathematical model is developed to describe the blood flow inside a curved microvessel driven by electroosmosis. In addition to this flow, the channel experiences electric double layer phenomenon due to zeta potential about -25 mV. Lubrication theory and Debye-Hückel approximation are employed to obtain an analytical solution for electric potential function. Computations of stream function, axial velocity, volume flow rate, and pressure rise are computed through low zeta potentials. The electroosmotic flow behaviour is governed by two dimensionless parameters: Helmholtz-Smoluchowski velocity and Debye-Hückel parameter. It is also examined that, how curvature affects the blood flow driven by the electroosmosis. Furthermore, the salient features of flow characteristics and trapping phenomena are presented. The results indicate that pressure gradient and wall shear stress reduce with increasing the curvature effects however the trapping is more with high curvature of the microvessel. The observations also indicate promising features of micromixer, micro-peristaltic pumps, and organ-on-a-chip devices. They may further be exploited in diagnosis/mixing of samples, and haemodialysis respectively.

Electro-Osmosis Modulated Viscoelastic Embryo Transport in Uterine Hydrodynamics: Mathematical Modeling.

Embryological transport features a very interesting and complex application of peristaltic fluid dynamics. Electro-osmotic phenomena are also known to arise in embryo transfer location. The fluid dynamic environment in embryological systems is also known to be non-Newtonian and exhibits strong viscoelastic properties. Motivated by these applications, the present article develops a new mathematical model for simulating two-dimensional peristaltic transport of a viscoelastic fluid in a tapered channel under the influence of electro-osmosis induced by asymmetric zeta potentials at the channel walls. The robust Jeffrey viscoelastic model is utilized. The finite Debye layer electro-kinetic approximation is deployed. The moving boundary problem is transformed to a steady boundary problem in the wave frame. The current study carries significant physiological relevance to an ever-increasing desire to study intrauterine fluid flow motion in an artificial uterus. The consequences of this model may introduce a new mechanical factor for embryo transport to a successful implantation site. Hydrodynamic characteristics are shown to be markedly influenced by the electro-osmosis, the channel taper angle, and the phase shift between the channel walls. Furthermore, it is demonstrated that volumetric flow rates and axial flow are both enhanced when the electro-osmotic force aids the axial flow for specific values of zeta potential ratio. Strong trapping of the bolus (representative of the embryo) is identified in the vicinity of the channel central line when the electro-osmosis opposes axial flow. The magnitude of the trapped bolus is observed to be significantly reduced with increasing tapered channel length whereas embryo axial motility is assisted with aligned electro-osmotic force.

Time-dependent peristaltic analysis in a curved conduit: Application to chyme movement through intestine.

A theoretical model of time-dependent peristaltic viscous fluid flow through a curved channel in the presence of an applied magnetic field is investigated. The results for stream function, pressure distribution and mechanical efficiency are obtained under the assumptions of long wavelength and low Reynolds number approximation. Pressure fluctuations due to an integral and a non-integral number of waves along the channel length are discussed under influence of channel curvature and magnetic parameter. Two inherent characteristics of peristaltic flow regimes (trapping and reflux) are discussed numerically. The mechanical efficiency of curved magnetohydrodynamic peristaltic pumping is also examined. The magnitude of pressure increases with an increasing channel curvature and magnetic parameter. Reflex phenomenon is analyzed in the Lagrangian frame of reference. It is observed that reflex in the curved channel is higher than in the straight channel. The trapped fluid in a curved channel is studied in the Eulerian frame of reference and it contains two asymmetric boluses. The size of the lower bolus grows and the upper bolus decreases with increasing effect of magnetic strength. Pumping efficiency of the peristaltic pump is low for curved channel flow than for straight channel flow. Also, the pumping efficiency is comparatively low at the high effect of the magnetic parameter.

Atrial septal aneurysm: a new classification in two hundred five adults.

Atrial septal aneurysm is a localized "saccular" deformity, generally at the level of the fossa ovalis, which protrudes to the right or the left atrium or both. For 39 months we prospectively analyzed 205 consecutive patients in whom atrial septal aneurysm was diagnosed echocardiographically. The direction and movement of atrial septal aneurysms were carefully studied in multiple views, and, according to our findings, we now propose a new classification: type 1R if the bulging is in the right atrium only, type 2L if the bulging is in the left atrium only, type 3RL if the major excursion bulges to the right atrium and the lesser excursion bulges toward the left, type 4LR if the maximal excursion of the atrial septal aneurysm is toward the left atrium with a lesser excursion toward the right atrium, type 5 if the atrial septal aneurysm movement is bidirectional and equidistant to both atria during the cardiorespiratory cycle. We found an incidence of 1.9%, a mean age of 63 years (25 to 97 years), a female/male ratio of 2:1, valvular regurgitation 74%, hypertension 64%, left ventricular hypertrophy 38%, coronary heart disease 32%, patent foramen ovale 32%, pulmonary hypertension 31%, stroke 20%, dysrhythmias 16%, valvular prolapse 15%, and atrial septal defect 3%. No differences were found between mobile and motionless types of atrial septal aneurysm. However, differences were found between predominantly left bulging or right bulging atrial septal aneurysm (134 versus 57 patients), as well as other variables. All types of atrial septal aneurysm have particular clinical or echocardiographic characteristics. The new classification is a complete, simple, and practical form. Atrial septal aneurysm is associated with congenital and acquired heart diseases but also can present as an isolated abnormality.

Bacteraemia at the University Hospital of the West Indies--a report of 222 cases.

A total of 222 cases of septicaemia was recorded at the University Hospital of the West Indies between June 1982 and June 1983. This gave an overall incidence of 16.1 per 1000 admissions. The 233 bacterial strains isolated comprised 100 Gram-positive and 133 Gram-negative organisms with Klebsiella pneumoniae, Streptococcus pneumoniae and Staphylococcus aureus being the most frequent. Highest rates of septicaemia were recorded in patients less than 1 year and over 50 years of age. Septicaemia caused by Gram-positive organisms was predominantly a disease of children whereas that caused by Gram-negative organisms arose more often in neonates and in patients over 50 years of age. A predisposing factor was noted in 104 patients of whom 42 had neoplastic disease. The most frequently identified initial sites of infection were the respiratory tract, the gastro-intestinal tract and the meninges. Most blood stream infections were community-acquired, three quarters of all septicaemic patients being admitted to the departments of medicine or paediatrics. There were 11 cases of polymicrobial septicaemia caused predominantly by Gram-negative organisms in patients with underlying disease. Appropriate antimicrobial drugs were administered to 57% of septicaemic patients whereas 17% received superfluous antimicrobial therapy. In those patients who received inappropriate antimicrobial therapy there was a marked increase in mortality. Forty of 61 deaths were attributed to septicaemia. Mortality from septicaemia caused by Gram-negative organisms was 21% compared with 13% for that caused by Gram-positive organisms. The organisms associated with the highest case fatality rates were Escherichia coli, 53%; Enterobacter sp., 27%; and beta-haemolytic streptococci 24%. There were no deaths from septicaemia caused by Haemophilus influenzae, Salmonella sp. or Serratia sp. The highest mortality rates were associated with neoplastic disease, diabetes, polymicrobial septicaemia, urinary tract infections and old age.

Cerebrospinal fluid C-reactive protein in the laboratory diagnosis of bacterial meningitis.

Samples of cerebrospinal fluid from 112 cases of suspected meningitis were tested for the presence of C-reactive protein (CRP), using a qualitative and quantitative slide test. Bacterial meningitis was confirmed in 34 patients, based on CSF and blood culture results, and/or elevated CSF white blood cell (WBC) count and typical biochemical profile. There were 8 patients with early onset, and 3 who had received prior antimicrobial therapy among the 5 neonates, 23 children, and 6 adults with bacterial meningitis. Organisms recovered from CSF, and/or blood, included Haemophilus influenzae 14, Streptococcus pneumoniae 9, Streptococcus group B-5, Staphylococcus aureus 2, E. coli 2 and Klebsiella pneumoniae 1. Slide test was positive for CRP in 33 cases, giving a sensitivity of 97% which compared favourably with elevated CSF protein 33%, decreased CFS glucose 64.7% CSF glucose/blood glucose less than 1/2, 85%, raised CSF WBC 38.2%, raised CSF PMN 61.7%, CSF culture positive 88.2%, and CSF gram-positive 82.5%. Slide test was positive for CRP in 1 of 78 CSF samples negative for bacterial meningitis, giving a specificity of 98%. It was concluded that testing of CSF for CRP is a simple, rapid and accurate method for the laboratory diagnosis of bacterial meningitis, which is particularly appropriate for areas lacking adequate laboratory facilities.

Neonatal septicaemia at the University Hospital of the West Indies - abstract

Seventy-one cases of neonatal septicaemia were recorded at the University Hospital of the West Indies between June 1982 and May 1985. The 72 bacterial strains isolated comprise 42 gram-positive and 30 gram-negative organisms, with Group B streptococcus (GBS), Klebsiella pneumoniae and Staphylococcus aureus being the most frequent. There were only 5 cases of E. coli septicaemia. Twenty-six percent of cases (including 24 percent of GBS infections) were early onset 91 percent occurred during the first three weeks of life. Early onset septicaemias were associated with prematurity, prolonged rupture of membranes, respiratory distress and high mortality. A focus of infection was identified in 64 percent of septicaemias the majority of which were associated with infections of the respiratory tract, gastrointestinal tract, central nervous system and skin. A predisposing factor was noted in 71 percent of cases and 12.6 percent of cases were related to infection outbreaks. The efficacy of pencillin at 50,000u/kg/d for the treatment of GBS septicaemia was questionable. Gentamycin was associated with 43 percent treatment failure rate in the gram-negative septicaemias. Mortality was 40 percent for E. coli septicaemias, 36 percent for GBS septicaemias, 46 percent for early onset septicaemias and 21 percent overall.

Cerebrospinal fluid C-reactive protein in the laboratory diagnosis of bacterial meningitis - abstract

Samples of cerebrospinal fluid (CSF) from 112 cases of suspected meningitis were tested fo the presence of C-reative protein (CRP) using a qualitative and quantitative slide test. Bacterial meningitis was confirmed in 34 patients based on CSF and blood culture results and/or elevated CSF white blood cell (WBC) count and typical CSF biochemical profile. There were eight patients with early onset and 3 who had received prior antimierobial therapy among the 5 neonates, 23 children, and 6 adults with bacterial meningitis. Organisms recovered from CSF and/or blood included Haemophilus influenzae (14), Strptococcus pneumoniae (9), Streptococcus group B (5), Staphylococcus aureus (2), E. coli (2) and Klebsiella pneumoniae (1). Slide test was positive for CRP in 33 cases, giving a sensitiviy of 97 percent which compare favourably with elevated CSF protein (33 percent), decreased CSF glucose (64.7 percent), CSF glucose/blood glucose 1/2 (85 percent), raised CSF WBC (38.2 percent), raised CSF PMN (61.7 percent), CSF PMN culture positive (88.2 percent) and CSF gram stain positive (82.5 percent). Slide test was positive for CRP in 1 of 7 CSF samples which were negative for bacterial meningitis, giving a specificity of 98 percent). It is concluded that testing of CSF for CRP is a simple, rapid and accurate method for the laboratory diagnosis of bacterial meningitis, which is particularly appropriate for areas lacking adequate laboratory facilities (AU)

Multi-resistant salmonella ohio infections at the University Hospital of the West Indies - abstract

During 1982-83, there was a substantial increase in the number of S.ohio infections at the University Hospital of the West Indies, which coincided with the appearance of strains resistant to chloramphenicol, cotrimoxazole, ampicillin, neomycin and carbenicillin. Multi-resistant strains of S.ohio accounted for 71 of the 367 salmonella isolates during this period (19.3 percent). All of the 40 strains tested were able to transfer resistance determinants to E. coli, K12J53-2. S.ohio was cultured from stool (60), blood (5), wounds and abscesses (4), and post-mortem material (2). Eighty per cent of infections occurred in children less than two years of age and was often associated with gastroenteritis in malnourished children. Two infants with severe gastroenteritis and bronchopneumonia died. There were a number of unusual S.ohio isolates, including 2 cases of septicaemia in children receiving chloramphenicol for H. influenzae meningitis, a scrotal abscess secondary to extravasion of urine and infected scabies in a child with marasmic kwashiorkor. The emergence of a multi-resistant S.ohio capable of transferring antibiotic resistance to other organisms is of particular concern where S.typhi is endemic (AU)

Antimicrobial resistance in clinical isolates of staphylococcus aureus at the University Hospital of the West Indies

Antimicrobial resistance in clinical isolates of staphylococcus aureus encountered at the University Hospital of the West Indies from January to December 1980 was studied. Compared to the data from 1975, there was a marked increase of penicillin resistance in out-patient strains, approximating that found in in-patient isolates (82 percent and 84 percent). Resistance to cotrimoxazole also increased (from 1 percent to 2.1 percent) while there was a decrease in the prevalence of resistance to streptomycin, trtracycline and chloramphenicol. Methicillin resistance was not found. The high prevalence of penicillin resistance in out-patients strains suggests that a penicilinase-resistant penicillin must be selected in the initial therapy of all suspected staphylococcal infections whether in or out of the hospital. The non-occurence of methicillin resistance in this institution should not lead to complacency, as sudden and epidemic outbreaks of methicillin-resistant strains have occured in hospitals in which there was no previous resistance. The epidemiological and therapeutic problems associated with methicillin-resistant strains are further discussed (AU)

Risk factors for carcinoma of the uterine cervix in Jamaican women

Risk factors of cervical cancer include early age at coitus, multiple sexual partners and antibodies to herpes simplex virus, type 2 (HSV-2). To examine the interrelationships of these risk factors, a comparison was made between 78 histologically confirmed cancer cases (stages O-IV) and 151 control women in Jamaica. The rank of order of the percentages of control women with low socioeconomic status, first coitus before 20 years of age, first pregnancy before 20 years of age and more than two sexual partners were: 77, 97, 65, and 76 respectively. The percentage of women with cancer who had first coitus before 20 years of age (77) and 2 or more partners (55) were lower than that of controls. A third factor associated with cervical cancer is the presence of HSV-2 antibodies. The age-specific prevalence of HSV-2 antibodies varied from 7 percent to 32 percent in women aged 21-69 years. An increase in prevalence of HSV-2 was observed with increasing age. The age-adjusted prevalence was 11 per cent. The age-specific occurrence of HSV-2 antibodies in cancer cases were not statistically significant as compared with matched controls (p> 0.01). The data suggest that infection with HSV-2 is a covariable of venereal factors, and the role of the virus in the genesis of some cases of cervical cancer in Jamaican women may not be excluded (AU)

Antibodies to herpes simplex virus (types 1 and 2) in Jamaican patients with cervical dysplasia and neoplasia

Antibody activity to Herpes simplex virus (HSV) types 1 and 2 was measured in sera from women with cervical dysplasia (19 cases), squamous-cell carcinoma, stages 0-4 (54 cases), other genital tumours (15 cases) and matched controls (60 cases) by the indirect immunofluorescent (IFA) test. The frequency of HSV-2 antibody activity was significantly greater in women with cervical cancer than in those with other genital tumours and in matched controls (p<0.05). No significant difference was observed for the HSV-2 antibody activity between women with cervical dysplasia and matched controls. The mean antibody titres to HSV-1 and HSV-2 were significantly higher in cancer cases than the respective titres in control groups (p<0.05). The cervical cancer cases were also analysed according to their clinical stage (Stages 0-4), and there was no significant variation either in frequency of antibody activity, or mean HSV-2 antibody titres. These preliminary findings suggest that there may be an association between HSV-2 and squamous cell carcinoma of uterine cervix in Jamaican women but further studies are required for meaningful conclusions to be drawn (AU)

Salmonellosis at the University Hospital of the West Indies

During 1982-83, there were 367 cases of salmonellosis at the University Hospital of the West Indies, caused by 50 different serotypes. Multiresistant strains of Salmonella ohio accounted for 19.3 percent of isolates, compared with 12 percent, 9.8 percent and 9.5 percent for Salmonella derby, Salmonella typhimurium and Salmonella typhi, respectively, Salmonella wre recovered from stool (303), blood (48), skin and soft tissue (7), urine (6), post-mortem material (2), sequestra (1), and sputum (1). Most infections occurred in younger age groups with 63 percent in children < 1 year if age. Twenty patients developed locallising infections. The 48 blood culture isolates included 25 S. tryphi and 23 other salmonella species. Fifteen patients with non-typhoid bloodstream infections developed septicaemia, and 13 of these had underlying disease, whereas only 1 of 8 bacteraemic patients had underlying disease. All S. ohio isolates were resistant to chloramphenicol, ampicillin, cotrimoxazole, neomycin and carbenicillin, and resistance determinants were transferred to E. coli K12J53-2. It was concluded that non-typhoid salmonellas were responsible for a significant degree of morbidity during the period of this study (AU)

Risk factors for carninoma of the uterine cervix in jamaican women

Risk factors of cervical cancer include early age at coitus, multipli sexual partners and antibodies to herpes simplex virus, type 2(HSV-2). To examine the interrelationships of these risk factors, a comparison was made between 78 histologically confirmed cancer cases (stages 0-IV) and 151 control women in Jamica. The rank of order of the percentages of control women with low socieconomic status, first coitus before 20 years of age, first pregnancy before 20 years of age and more than two sexual partners were: 77,97,65, and 76 respectively. The percentage of women with cancer who had coitus before 20 years of age (77) and 2 or more partners (55) were lower than that of controls. A third factors associated with cervical cancer is the presence of HSV-2 antibodies. The age-specific prevalence of HSV-2 antibodies varied from 7% to 32% in women aged 21-69 years. An increase in prevalence of HSV-2 antibodies was observed with increasin age. The age-adjusted prevalence was 11 per cent. The age-specific occurrence of HSV-2 antibodies in cancer cases varied from 6% to 28% with a prevalence of 7.8%. The mean antibody titres in cancer cases were not statistically significant as compared with matched controls (p > 0.01). the data suggest that infection with HSV-2 is a covariable of veneral factors, and the role of the virus in the genesis of some cases of cervical cancer in Jamaican women may not be excluded