SA Heart consensus statement on closure of patent foramen ovale 2021

A patent foramen ovale (PFO) is associated with numerous clinical conditions. The most severe of these is cryptogenic stroke. This consensus statement aims to provide a clinical guideline on which patients should be offered PFO closure.

Renal function in patients with significant tricuspid regurgitation: pathophysiological mechanisms and prognostic implications

BACKGROUND

The pathophysiological mechanisms linking tricuspid regurgitation (TR) and chronic kidney disease (CKD) remain unknown. This study aimed to determine which pathophysiological mechanisms related to TR are independently associated with renal dysfunction and to evaluate the impact of renal impairment on long-term prognosis in patients with significant (≥ moderate) secondary TR.

METHODS

A total of 1234 individuals (72 [IQR 63-78] years, 50% male) with significant secondary TR were followed up for the occurrence of all-cause mortality and the presence of significant renal impairment (eGFR of <60 mL min-1  1.73 m-2 ) at the time of baseline echocardiography.

RESULTS

Multivariable analysis demonstrated that severe right ventricular (RV) dysfunction (TAPSE < 14 mm) was independently associated with the presence of significant renal impairment (OR 1.49, 95% CI 1.11 to 1.99, P = 0.008). Worse renal function was associated with a significant reduction in survival at 1 and 5 years (85% vs. 87% vs. 68% vs. 58% at 1 year, and 72% vs. 64% vs. 39% vs. 19% at 5 years, for stage 1, 2, 3 and 4-5 CKD groups, respectively, P < 0.001). The presence of severe RV dysfunction was associated with reduced overall survival in stage 1-3 CKD groups, but not in stage 4-5 CKD groups.

CONCLUSIONS

Of the pathophysiological mechanisms identified by echocardiography that are associated with significant secondary TR, only severe RV dysfunction was independently associated with the presence of significant renal impairment. In addition, worse renal function according to CKD group was associated with a significant reduction in survival.

Dietary supplements containing prohibited substances

Dietary supplement use among athletes to enhance performance is proliferating as more individuals strive for obtaining that chemical competitive edge. As a result the concomitant use of dietary supplements containing performance-enhancing substances of those falling in the categories outlined in the current review, can also be expected to rise. This despite ever-increasing sophisticated analytical methodology techniques being used to assay dietary supplement and urine samples in doping laboratories. The reasons for this include that a variety of these chemical entities, many of them on the prohibited drug list of the WADA, are being produced on commercial scales in factories around the world (ephedrine and pseudoephedrine, sibutramine, methylhexaneamine, prohormones, 'classic' anabolic steroids, clenbuterol, peptide hormones etc.), aggressive marketing strategies are being employed by companies and these supplements can be easily ordered via e.g. the internet. It can also be anticipated that there will be an increase in the number of supplements containing 'designer' steroids and other 'newer' molecules. Chromatographic techniques combined with mass spectrometry leading to identification of molecular fragments and productions will assist in determining these substances. To prevent accidental doping, information regarding dietary supplements must be provided to athletes, coaches and sports doctors at all levels of competition. The risks of accidental doping via dietary supplement ingestion can be minimized by using 'safe' products listed on databases, e.g. such as those available in The Netherlands and Germany.

QTc prolongation prior to angiography predicts poor outcome and associates significantly with lower left ventricular ejection fractions and higher left ventricular end-diastolic pressures

Background

QT prolongation on the surface ECG is associated with sudden cardiac death. The cause of QT prolongation in ischaemic heart disease (IHD) patients remains unknown, but may be due to a complex interplay between genetic factors and impaired systolic and/or diastolic function through as yet unexplained mechanisms. It was hypothesised that QT prolongation before elective coronary angiography is associated with an increased mortality at six months.

Methods

Complete records of 321 patients who underwent coronary angiography were examined for QT interval corrected for heart rate (QTc), left ventricular ejection fraction (LVEF), left ventricular end-diastolic pressure (LVEDP) and known ischaemic heart disease risk factors. Patients were designated long QTc (LQTc) when they had prolonged QTc intervals or normal QTc (NQTc) when the QTc interval was normal. Patients with atrial fibrillation, bundle branch blocks, no ECG in the 24 hours before angiography, or a creatinine level > 200 μmol/l were excluded. Survival was determined telephonically at six months.

Results

Twenty-eight per cent of the total population had LQTc. During follow up, 15 patients (4.7%) died suddenly, 73% of whom had a LQTc. LQTc was significantly associated with mortality (LQTc 12% vs NQTc 1.7%; p < 0.01), and with lower but normal LVEF (LQTc 52.9 ± 15.4% vs NQTc 61.6 ± 13.6%; p < 0.01), higher LVEDP at LVEF > 45% (LQTc 19.2 ± 9.0 mmHg vs NQTc 15.95 ± 7.5 mmHg; p < 0.05), hypercholesterolaemia and a negative family history of IHD.

Conclusion

In patients with sinus rhythm and normal QRS width, QTc prolongation before coronary angiography predicted increased mortality at six months. QTc also associated strongly with left ventricular systolic and diastolic dysfunction, hypercholesterolaemia and a negative family history of IHD.

Efficacy, safety and potential clinical roles of the COX-2-specific inhibitors

About three decades ago, the primary mechanism of action of the non-steroidal anti-inflammatory drugs (NSAIDs) was elucidated when their inhibitory action on the production of prostaglandins was discovered. It was found that their action is centred on the inhibition of the cyclooxygenase (COX) enzyme responsible for converting arachidonic acid to prostaglandins. More recently, it was discovered that at least two isoforms of the enzyme exist. While the COX-1 isoenzyme is mainly constitutive, the COX-2 form is inducible. The constitutive form is principally associated with physiological/homeostatic functions while the inducible form is involved in inflammatory responses. Because many of the unwanted effects of the NSAIDs have been associated with COX-1 inhibition, specific drugs with a high inhibitory activity toward the COX-2 isoenzyme have been developed in recent years. The efficacy, safety and potential clinical roles of these COX-2-specific inhibitors are addressed in this review article.

Enhancing effect of temperature on the transmucosal penetration kinetics of 17 beta-estradiol

Human vaginal mucosa may be used as a model of buccal mucosa for in vitro permeability studies using various chemical compounds. Rectilinear temperature dependence of water flux across vaginal mucosa between 25 degrees C and 41 degrees C has been shown. The objective of this study was to examine the behaviour of the above barrier on fluxes of 17 beta-estradiol at various temperatures. Frozen vaginal mucosa specimens from a single patient were used (snap-frozen in liquid nitrogen and stored at -85 degrees C). The permeability to tritiated 17 beta-estradiol was determined using a continous flow-through perfusion system at temperatures of 20 degrees C, 25 degrees C, 30 degrees C, 37 degrees C and 41 degrees C. Histological examinations were performed before and after permeability experiments. Estimated steady state flux values were used at 20 degrees C, 25 degrees C and 30 degrees C. Estimated and true mean 17 beta-estradiol steady state flux rates (20-24 h) were found to be 415 +/- 27 standard error of the Mean (SEM), 848 +/- 60 SEM, 1355 +/- 77 SEM, 1436 +/- 37 SEM and 1482 +/- 35 SEM cpm.cm-2.min-1, at temperatures of 20 degrees C, 25 degrees C, 30 degrees C, 37 degrees C and 41 degrees C, respectively. A non-linear regression analysis and plot (R2 = 0.9941) displayed a curvilinear flux-temperature relationship. The results from this study showed that, notwithstanding cellular damage, the principal physical permeability barrier governing permeation kinetics was non-linearly temperature-dependent between the temperatures studied, providing further support for the concept that this barrier is lipoidal in nature.

Enhancement of transmucosal permeation of cyclosporine by benzalkonium chloride

OBJECTIVES

Permeation of cyclosporin A (CsA) through intact and de-epithelialized human vaginal mucosa in the presence and absence of benzalkonium chloride (BZCl) was tested.

MATERIALS AND METHODS

Human vaginal mucosa (snap-frozen in liquid nitrogen, stored at -85 degrees C) had been used for permeability experiments. CsA permeation through thawed frozen intact and de-epithelialized vaginal mucosa was determined using a flow-through diffusion apparatus (20 degrees C, 24 h). Flux rates for CsA across these two mucosae were determined in the presence and absence of 0.01% BZCl. ANOVA and Duncan's multiple range test were used to test for steady-state and an unpaired t-test with Welch's correction was used to test for differences between the mean flux values at each time point (significance level of 5%). A piece of thawed tissue from each patient, before and after de-epithelialization, was placed in formalin and histologically examined.

RESULTS

Flux rates of CsA across intact vaginal mucosa tended to increase by 28-46% in the presence of 0.01% BZCl, and CsA across de-epithelialized mucosa by approximately 28%. The latter differences were statistically significantly higher after 10 h. Flux rates across de-epithelialized mucosa were 52-140% higher in the presence of 0.01% BZCl (statistically significantly higher after 12 h).

CONCLUSIONS

The permeation of CsA through intact and de-epithelialized human vaginal mucosa can be enhanced by 0.01% BZCl.

The effect of betel nut extract on cell growth and prostaglandin endoperoxide synthase in human epidermoid carcinoma cells

The objective of this study was to find out whether prostaglandin endoperoxide synthase (PHS) involves the action of betel nut extract (BNE) on the growth of oral cancers. Therefore, growth and PHS activity were examined in two human oral carcinoma cell lines (OEC-M1 and KB) and one normal fibroblast cell line (NF) in the presence of increasing BNE concentration. BNE at concentrations above 50 microg/ml significantly inhibited the cell growth of OEC-M1 after 72 h in culture, of KB and NF after 48 h in culture. The IC50 of BNE in OEC-M1, KB and NF at 24 h in culture was about 406, 37.5 and 140 microg/ml respectively. PHS activity in OEC-M1 was significantly increased by low BNE concentrations (50 microg/ml, 114%; 100 microg/ml, 33%; 150 microg/ml, 30%) but significantly reduced at higher BNE concentrations (300 microg/ml, 33%; 500 microg/ml, 61%). The PHS activity in KB was significantly inhibited by BNE and this effect was intensified as concentrations increased (50 microg/ml, 31%; 100 microg/ml, 24%; 150 microg/ml, 43%; 300 microg/ml, 60%; 500 microg/ml, 92%). Similar to that in OEC-M1, the PHS activity in NF was significantly increased at low BNE concentrations (50 microg/ml, 139%; 100 microg/ml, 87%;150 microg/ml, 77%) but reduced at higher concentrations (300 microg/ml, 55%; 500 microg/ml, 72%). The PHS activity in all cell lines was almost completely blocked by indomethacin (5 x 10(-6) M). We conclude that these findings suggest that PHS may be an important biochemical mediator of the effect of BNE on the growth of two human oral carcinoma cell lines.

The effect of radiation on the permeability of human saphenous vein to 17 beta-oestradiol

Radiation therapy is an effective way of treating many forms of cancer, however, there are some indications that it may facilitate the development of metastasis. The question arises whether radiation therapy during cancer treatment might result in an alteration of the permeability of the tissues being treated. This alteration in the permeability might lead to metastatic cells escaping from the irradiated tissue, leading to the spread of cancer to other sites in the body. Because of the above implication, we determined the diffusion kinetics of a radioactive marker, 17 beta-oestradiol, through human saphenous vein before and after a single half hour exposure to 60 Gy of 60Co gamma-irradiation. Six clinically healthy saphenous vein specimens (mean patient age +/- standard deviation 57 +/- 13 years; age range 41-77 years) were obtained during cardiac surgery. In vitro flux rates of 17 beta-oestradiol were determined through use of a flow-through diffusion apparatus immediately after irradiation for a period of 24 hours. No statistically significant differences could be demonstrated for the flux rates of 17 beta-oestradiol through the non-irradiated and 60 Gy irradiated saphenous vein tissue. These findings strongly suggest that irradiation at 2 Gy/min and a total dose of 60 Gy would not alter the permeability of the venous wall. We have demonstrated that the in vitro flow-through diffusion method is capable of measuring permeability aspects of endothelial cell layers in saphenous vein biopsies under conditions resembling clinical reality.

Effects of two barrier creams on the diffusion of benzo[a]pyrene across human skin

Barrier hand creams, often containing antiseptic agents, may provide a form of protection not only for health care professionals, but also for workers in the chemical and pharmaceutical industries. To evaluate the efficacy of two such barrier creams available on the South African market, the in vitro diffusion of a model compound, benzo[a]pyrene, through human skin at 20 degrees and 37 degrees C was studied. Treated (10 min) and untreated human skin disks (4 mm in diameter) were mounted in flow cells of a continuous flow-through diffusion apparatus. Buffer/tritiated benzo[a]pyrene was collected from the acceptor chambers at 2-hour intervals for a total of 24 hours and counted in a liquid scintillation counter. At 20 degrees C no significant differences could be detected between the flux rates of benzo[a]pyrene across barrier cream treated and untreated skin. However, at 37 degrees C Skinguard significantly increased flux rates of this carcinogen. Skin barrier creams therefore need to be carefully scrutinised with respect to their protective effects because the latter may vary for molecules with different chemical properties.

A comparative light-microscopic, electron-microscopic and chemical study of human vaginal and buccal epithelium

The scarcity of sizeable specimens of normal oral mucosa for experimental purposes has hampered research on oral epithelium. Because large specimens of viable human vaginal mucosa are readily available and because vaginal and buccal epithelia are microscopically similar, vaginal mucosa has been used successfully to establish a human cyst model in experimental animals. The ultrastructure and distribution of keratin filaments in these epithelia are also similar, as is their permeability to water and a number of chemical substances. Therefore, if vaginal mucosa could be substituted for buccal mucosa it would expedite research on the epithelium of buccal mucosa. To strengthen further the concept that vaginal epithelium could replace buccal epithelium in certain experimental studies, the thickness of these epithelia, their patterns of surface keratinization, the presence or absence of intercellular lipid lamellae and their lipid contents were now compared. Thirty-three specimens of vaginal mucosa from postmenopausal women and 36 of buccal mucosa were investigated. To compare the thickness of the epithelial layers the number of cell layers in sections of 20 vaginal and 20 buccal mucosal specimens were counted in the three thickest and three thinnest regions of each specimen. Surface keratinization was evaluated on sections stained with the Picro-Mallory method. To demonstrate lipid lamellae two vaginal and two buccal mucosa specimens were examined electron microscopically after normal fixation and postfixation in ruthenium tetroxide. Following solvent extraction of 11 vaginal and 14 buccal epithelia, quantitative lipid analyses were performed using thin-layer chromatography. No statistically significant differences were found between the maximum and minimum number of epithelial cell layers. The patterns of surface keratinization and the distribution and appearance of the lipid lamellae in the intercellular spaces were similar. The lipid composition of the two epithelia corresponded, except for the cholesterol esters and glycosylceramides, which were higher in buccal epithelium. Ceramides for vaginal epithelium and triglycerides for buccal epithelium were not determined. Based on structural similarities, a similar lipid composition and earlier findings, it is concluded that vaginal epithelium can be used as a substitute for buccal epithelium in certain in vitro, and possibly for in vivo, studies.

Areca nut extract lowers the permeability of vaginal mucosa to reduced arecoline and arecaidine

Areca nut chewing has been implicated in the development of oral cancer and oral submucous fibrosis. Arecoline and arecaidine, which are alkaloids present in the areca nut, are thought to play a major role in the development of adverse effects resulting from this chewing habit. Because these alkaloids appear to be associated with the development of the above diseases, we determined their diffusion kinetics through human vaginal mucosa in the presence and absence of a 1% areca nut extract. Seven clinically healthy vaginal mucosa specimens (mean patient age+/-standard deviation, 52+/-13 years; age range, 38-74 years) were obtained during surgery. In vitro flux values of reduced arecoline and arecaidine (r-arecoline and r-arecaidine) were determined through use of a flow-through diffusion apparatus. Analysis of variance, a Duncan multiple range test, and an unpaired t-test were used to determine steady state kinetics and flux differences over time intervals. The flux values across vaginal mucosa of r-arecoline and r-arecaidine were decreased in the presence of 1% areca nut extract. For r-arecoline, these flux values were significantly lower statistically when compared to those obtained in the absence of areca nut extract. These findings concur with results previously obtained for water, where the astringent action of the tannins present in the areca nut extract was thought to alter the barrier properties of the epithelium, resulting in decreased permeability.

A literature review and pilot study to characterise the treatment of burning mouth syndrome

Although the definition of burning mouth syndrome (BMS) can vary, the most commonly accepted is that of a burning sensation of normal appearing oral mucosa with no apparent underlying local or systemic contributing factors. The condition can be classified according to the patterns of burning experienced, the severity of the burning, as well as the pattern of onset. The management of these patients is difficult, since they are often seen by numerous clinicians and many unnecessary tests are performed in the hope of finding an underlying physical cause for the burning. No precise information pertaining to the natural history of BMS could be found. This paper consists of a selective review of the literature on BMS as well as a pilot study involving the standardised collection of data on 10 patients (9 women and 1 man) with BMS. These patients will be followed up in the long term in order to gather information pertaining to the natural history of this condition. No detectable local or systemic cause for the burning sensation could be found for any of the 10 subjects. The role of somatisation as a mechanism for burning sensation was investigated and certain proposals have been put forward regarding the management of such patients.

Effects of three penetration enhancers on transcorneal permeation of cyclosporine

PURPOSE

To investigate the permeation of cyclosporin A (CsA) through fresh and frozen human corneas in the presence and absence of three penetration enhancers: benzalkonium chloride (BZCl), dimethylsulfoxide (DMSO), and Cremophor-EL.

METHODS

Human corneas, unsuitable for transplantation, were either freshly used for permeability experiments or snap-frozen in liquid nitrogen and stored at -85 degrees C. CsA permeation through either fresh or thawed frozen corneal tissue was determined using a flow-through diffusion apparatus (20 degrees C for 24 hours). Flux rates for CsA were determined in the presence and absence of the penetration enhancers 0.01% BZCl, 20% DMSO, and Cremophor-EL (10% and 20%). Analysis of variance and Duncan's multiple-range test were used to test for steady state, and an unpaired Student t test with Welch's correction was used to test for differences between the mean flux values at each time point. A significance level of 5% was used for all of the statistical tests.

RESULTS

No statistically significant differences in flux values of CsA could be detected between fresh and frozen corneas. In the presence of Cremophor-EL (10% and 20%) and 0.01% BZCl, statistically significant increases in flux values of CsA before 16 hours and after 16 hours, respectively, could be observed. In the presence of 20% DMSO, no statistically significant increases in flux values could be detected.

CONCLUSIONS

The permeation of CsA through human corneas appeared to be enhanced by the presence of BZCl and Cremophor-EL. Additionally, it was shown that the flux rate of CsA across fresh and frozen corneas was not significantly different.

Permeability of vaginal mucosa to water at normal and elevated temperatures

A number of studies have clearly demonstrated that human vaginal mucosa may be used as a model of buccal mucosa for a variety of in vitro permeability studies on drugs and other chemical compounds. Furthermore, at between 25 degrees and 37 degrees C, a linear temperature-dependence of water flux across this mucosa, which was attributed to an increased fluidity of the principal lipoidal permeability barrier, was found to exist. The objective of the present study was to examine the behaviour of the above barrier on water fluxes at normal and elevated temperatures. Clinically healthy human vaginal mucosa specimens were obtained from excess tissue removed during a vaginal hysterectomy from a single patient, snap-frozen in liquid nitrogen and stored for 6 months at -85 degrees C. Seven sections from the mucosa were thawed in phosphate-buffered saline (PBS) and mounted in flow-through diffusion cells (exposed area 0.039 cm2). Their permeability to tritiated water was determined using a continuous flow-through perfusion system at temperatures of 37 degrees, 39 degrees and 41 degrees C. Three permeability experiments were performed at each temperature setting. Specimens were subjected to histological examination before and after permeability experiments. Mean water flux rates at steady state (10-24 h) were found to be 2,356 +/- 71 SEM, 3,020 +/- 38 SEM and 3,659 +/- 116 SEM cpm. cm-2.min-1, at temperatures of 37 degrees, 39 degrees and 41 degrees C, respectively. A linear regression analysis and plot (r2 = 0.99) displayed a slope of 325 +/- 4 SEM cpm.cm-2.min-1/degree C. The results of this study showed that, notwithstanding cellular damage, the principal physical permeability barrier was linearly temperature-dependent between the temperatures studied, providing further support for the concept that this barrier is lipoidal in nature.

Namibian chewing stick, Diospyros lycioides, contains antibacterial compounds against oral pathogens

The twigs of Diospyros lycioides, a plant commonly known as "muthala", are frequently used as chewing sticks for the cleaning of teeth by rural and urban people in Namibia. Preliminary studies showed that a methanol extract of D. lycioides inhibited growth of selected oral pathogens. Subsequent bioassay-guided fractionation led to the isolation of four novel bioactive naphthalene glycosides, diospyrosides A, B, C, and D (1-4), and two known bioactive naphthoquinones, juglone (5) and 7-methyljuglone (6). The structures of the new compounds were elucidated using spectroscopic techniques including 1D and 2D NMR. These compounds inhibited the growth of oral cariogenic bacteria (Streptococcus mutans and Streptococcus sanguis) and periodontal pathogens (Porphyromonas gingivalis and Prevotella intermedia) at minimum inhibitory concentrations ranging from 0.019 to 1.25 mg/mL. Juglone exhibited the strongest inhibitory activity among these compounds.

Permeation of sumatriptan through human vaginal and buccal mucosa

Continued interest in the various routes by which sumatriptan may be administered prompted us to investigate its passage through buccal mucosa. Because human buccal mucosa is scarce, we proposed using the relatively abundant vaginal mucosa, which has been shown to have comparable diffusion rates for a number of widely varying molecules, as a model of buccal mucosa. In addition, by comparing these two tissues with respect to their permeability to sumatriptan, the human vaginal/buccal mucosa model could be further evaluated. Clinically healthy human vaginal and buccal mucosa specimens were used in the permeability studies. Permeability to sumatriptan was determined using a continuous flow-through diffusion system in the presence and absence of permeation enhancers. No statistically significant differences in permeability could be demonstrated for both mucosae toward sumatriptan. Flux values obtained in the absence and presence of glycodeoxycholate and lauric acid (1:1 molar ratio) to sumatriptan of buccal and vaginal mucosa, respectively, were not significantly different. The results obtained further support the hypothesis of the vaginal/buccal mucosal in vitro permeability model and suggest that this model may be used in conjunction with various absorption enhancers. Further studies on the buccal route of absorption of sumatriptan are thus warranted.

Penetration of benzo[a]pyrene through human buccal and vaginal mucosa

OBJECTIVE

The aim of this study was to compare buccal and vaginal mucosa with respect to their permeability to a potent carcinogen, benzo[a]pyrene.

STUDY DESIGN

Six clinically healthy vaginal mucosa specimens (mean patient age +/- standard deviation, 52+/-13.4 years; age range, 37-69 years) and 6 buccal mucosa specimens (from 5 male patients and 1 female patient: mean patient age +/- standard deviation, 32+/-5.2 years; age range, 24-39 years) were obtained during surgery. In vitro flux rates of benzo[a]pyrene across specimens were determined through use of a flow-through diffusion apparatus. Analysis of variance, a Duncan multiple range test, and an unpaired t test were used to determine steady state kinetics and flux differences over time intervals.

RESULTS

No statistically significant differences were observed between the overall mean flux values of benzo[a]pyrene across the 2 kinds of mucosa.

CONCLUSIONS

The findings further support the hypothesis that human vaginal mucosa can be used as a model for buccal mucosa in studies of permeability to various chemical compounds.

Effect of temperature on permeability of mucosa to water

In previous studies it has been demonstrated that frozen human vaginal mucosa can be used as a model of buccal mucosa for in vitro permeability studies on a variety of chemical compounds, including drugs. However, most of the latter studies have, for the sake of convenience, been conducted at room temperature (+/- 20 degrees C). The objective of the present study was to determine the effects of increased temperature on steady state flux rates of water through vaginal mucosa. Specimens of clinically healthy human vaginal mucosa were obtained from excess tissue removed during a vaginal hysterectomy from a single patient, snap-frozen in liquid nitrogen at -85 degrees C and banked for 8 months. After thawing in PBS buffer, seven sections from the vaginal mucosa were mounted in flow-through diffusion cells (exposed area 0.039 cm2) and their permeability to tritiated water determined using a continuous flow-through perfusion system at temperatures of 25 degrees, 30 degrees and 37 degrees C. Permeability experiments were performed in triplicate at each temperature setting. Specimens were examined histologically before and after permeability experiments. Mean water flux rates at steady state (16-24 h) were found to be 1760 +/- 22 SEM, 2623 +/- 63 SEM and 4155 +/- 70 SEM cpm. cm-2.min-1, at temperatures of 25 degrees, 30 degrees and 37 degrees C, respectively. A linear regression analysis and plot (r2 = 0.99) displayed a slope of 200 +/- 13 SEM cpm. cm-2.min-1/degree C. The results of this study clearly demonstrated the temperature-dependency of flux rates of water across vaginal mucosa, and this should be taken into account whenever the in vitro vaginal/buccal model is used at room temperature for predicting in vivo buccal drug absorption kinetics.

The culture of human buccal and vaginal epithelial cells for permeability studies

The objective of the present study was to develop a single improved technique to culture human vaginal and buccal epithelial cells, whereby the cultured cells can be used in drug permeability studies. Cells were obtained from healthy human vaginal and buccal mucosa following vaginal hysterectomies and various oral surgical procedures. Tissue obtained was washed extensively in phosphate buffered saline (PBS, pH 7.3) containing antibiotics and amphotericin-B. Tissue specimens were cut into small pieces and plated out in 24-well plates. After drying, the full medium was added. Cell growth occurred within 4-6 days from primary explants and confluency was reached within 2-3 weeks. Primary explants yielded epithelial cells with minimal fibroblast contamination. After trypsinization, cells were seeded into collagen-coated wells and onto Transwell membranes. Trypsinized cells grew best on collagen-coated surfaces yielding more than one layer. The average steady state flux for the collagen-coated membranes (ccm's) containing either buccal or vaginal epithelial layers towards water was 6-10 times lower than that found for the cell-free ccm's. Fluxes for cultured cells on ccm's were 3x higher than those obtained for intact buccal and vaginal mucosa. Growth and permeability to water of the vaginal and buccal epithelial cells were comparable, confirming the similarity of these two tissues and the suitability of using the former as a model for the latter in permeability to tritiated water.

The suitability of five liquid scintillation cocktails for use with a continuous flow-through mucosal perfusion system

Continuous flow-through perfusion systems can be successfully used to study the permeability of small mucosal samples to various permeants. The latter often need to be radiolabelled to enable detection by means of liquid scintillation counting. However, the efficacy of the latter is dependent on the liquid scintillation cocktail used. The present study was conducted to evaluate five liquid scintillation cocktails commercially available in South Africa. Although four out of the five cocktails had similar efficacies in the concentration range 0.05 to 50 nCi, this was not the case in the low range (0.01 to 0.5 nCi). Overall Ready Protein+ was the most efficacious and has the added advantage that this cocktail has protein solubilising properties. The latter is important when we extend our permeability studies to include small proteins.

Permeability of lichen planus lesions and healthy buccal mucosa to water

The resurgence of interest in the oral mucosa as a route for drug delivery requires a thorough understanding of the permeability of this tissue in health and disease. Previous work has indicated that non-keratinized oral mucosa is more permeable than its keratinized counterpart. It has been suggested that pathological hyperkeratotic mucosa, which was previously non-keratinized, would be more permeable than healthy tissue. Equivocal results obtained from animal studies in which chemical or mechanical irritation was used to induce a hyperplastic and hyperkeratotic epithelium, prompted us to conduct a study on the comparison of the permeability to water of lichen planus lesions and healthy buccal mucosa. Buccal mucosa was obtained from six patients with previously confirmed lichen planus and from six clinically healthy patients. Thawed biopsies from each specimen were mounted in flow-through diffusion cells and their permeability to tritiated water determined using a continuous flow-through perfusion system. Specimens were examined histologically before and after permeability experiments. No statistically significant differences between mean steady state flux values (10-20 h) for lichen planus tissue and healthy buccal mucosa were found. These results warrant further studies with other oral conditions associated with hyperkeratosis to establish whether the nature and course of the condition are determinants for the retention or loss of the epithelium's permeability characteristics.

Diffusion rates of vasopressin through human vaginal and buccal mucosa

The permeability to several chemical compounds and the histology of vaginal and buccal mucosa are very similar. Because vaginal mucosa is more abundant, it may be used as a model for the latter. To further develop the vaginal/buccal mucosa model, the objective of the present study was to evaluate the passage of a small polypeptide, vasopressin, across fresh and frozen specimens of these two mucosae. Specimens of fresh buccal and vaginal mucosa were taken from excised tissue obtained following vaginal hysterectomies and various oral surgical procedures. Pieces of buccal and vaginal tissue specimens obtained were used fresh or were snap-frozen and stored at -85 degrees C for periods of up to 10 months. Biopsies from fresh and thawed specimens were mounted in flow-through diffusion cells and their permeability to tritiated vasopressin was determined using a continuous flow-through perfusion system. Specimens were examined histologically before and after freezing as well as before and after permeability experiments and similarities between vaginal and buccal tissues verified. No statistically significant differences between flux values for fresh and frozen vaginal and buccal mucosa, respectively, were found. These results demonstrate that the permeation of vasopressin across fresh and frozen human vaginal and buccal mucosa is for practical purposes similar. These results further support the human vaginal/buccal mucosa model for in vitro permeability studies on therapeutically active compounds.

Binaphthalenone glycosides from African chewing sticks, Diospyros lycioides

Our laboratory has engaged in the exploration of active antimicrobial principles present in chewing sticks commonly used by the African and Middle Eastern countries as a mechanical oral hygiene aid in place of tooth brushing. During this investigation, a methanol extract from the twigs of Diospyros lycioides, a Namibia tooth cleaning stick, demonstrated antimicrobial activity against common oral pathogens including Streptococcus mutans and Porphyromonas gingivalis (MICs 2.5 and 0.156 mg/mL). Subsequent fractionation and purification of this extract led to the identification of two novel binaphathalenone glycosides: 1', 2-binaphthalen-4-one-2',3-dimethyl-1,8'-epoxy-1,4',5,5',8, 8'-hexahydroxy-8-O-beta-glucopyranosyl-5'-O-beta-xylopyranosyl(1-- >6) -beta-glucopyranoside (1) and 1',2-binaphthalen-4-one-2', 3-dimethyl-1,8'-epoxy-1,4',5,5',8,8'-hexahydroxy-5', 8-di-O-beta-xylopyranosyl(1-->6)-beta-glucopyranoside (2). Their structures were established using spectroscopic techniques. Examination of the antimicrobial activity of these two compounds revealed positive but only marginal growth inhibition against the test cariogenic pathogens, S. sanguis and Streptococcus mutans.

Penetration of human vaginal and buccal mucosa by 4.4-kd and 12-kd fluorescein-isothiocyanate-labeled dextrans

In a previous study we demonstrated that human vaginal mucosa was as permeable to water as was buccal mucosa. Water, however, is a very small molecule with a molecular weight of 18 d. To further explore similarities between these two types of mucosa with respect to permeability, it was decided to investigate the passage of two large, hydrophilic molecules across these epithelia. Specimens of fresh, clinically healthy human vaginal and buccal mucosa were taken from excised tissue obtained during vaginal hysterectomies and various oral surgical procedures. Seven biopsy materials from each specimen were mounted in flow-through diffusion cells (exposed area, 0.039 cm2), and their permeability to 4.4- and 12-kd fluorescein-isothiocyanate-labeled dextrans was determined through use of a continuous flow-through perfusion system. Dextran was detected by means of a fluorospectrophotometric method at excitation and emission wave lengths of 498 and 520 nm, respectively. Specimens were examined histologically before and after permeability experiments, and similarities between vaginal and buccal tissues were verified. No statistically significant differences between the flux values of the 4.4-kd dextran across vaginal and buccal mucosa were found. However, for the 12-kd dextran the flux rate across buccal mucosa was significantly higher than the rate across vaginal mucosa. These results demonstrate that human vaginal mucosa is for practical purposes as permeable as buccal mucosa to 4.4-kd hydrophilic molecules. This further supports the hypothesis that vaginal mucosa may be a useful model for studying the passage across buccal mucosa of chemical compounds and therapeutic agents that are less than approximately 4.4 kd in molecular mass. For a 12-kd dextran the flux rate across buccal mucosa is significantly higher than the flux rate across vaginal mucosa, and the model becomes inaccurate.

Permeation of 17beta-estradiol through human vaginal and buccal mucosa

Because of the relative scarcity of fresh human oral mucosa specimens for permeability studies, we investigated the use of human vaginal mucosa as a model of the former. In a previous study we demonstrated the comparable diffusion rate of water across human vaginal and buccal mucosa and proposed the use of the former as a suitable model of the latter for in vitro drug permeability studies. To further evaluate the human vaginal/buccal mucosa model, we decided to compare these two tissues with respect to their permeability to 17beta-estradiol. Clinically healthy human vaginal and buccal mucosa specimens were obtained during vaginal hysterectomies and different oral surgical procedures. The permeability of each tissue specimen to 17beta-estradiol was determined through the use of a continuous flow-through diffusion system. Specimens were examined histologically before and after experiments. Mean flux values for 17beta-estradiol across human buccal mucosa tended to be slightly higher than those observed for vaginal tissue, but no statistically significant differences could be demonstrated. The results from this study further support our hypothesis that human vaginal mucosa may be a suitable model of human buccal mucosa for in vitro drug permeability studies.

Comparative permeability of human vaginal and buccal mucosa to water

There is currently a resurgence of interest in the oral mucosa as a route for drug delivery. The relative scarcity of human oral mucosa for in vitro permeability studies, and the fact that vaginal mucosa is histologically similar and more abundant than the former, caused us to compare these 2 tissues with respect to their barrier properties to water. Specimens of fresh, clinically-healthy human vaginal and buccal mucosa from non-smokers were taken from excised tissue obtained during vaginal hysterectomies and various oral surgical procedures. Biopsies from each specimen were mounted in flow-through diffusion cells and their permeability to tritiated water determined using a continuous flow-through perfusion system. Specimens were examined histologically before and after permeability experiments and similarities between vaginal and buccal tissues verified. No statistically significant differences between mean steady state flux values (10-16 h) for vaginal and buccal mucosa, respectively, were found. Human vaginal mucosa is therefore as permeable as buccal mucosa to water, and these results warrant further investigation with other compounds to establish whether vaginal mucosa may be a useful model for buccal mucosa for drug permeability studies.

Synthesis of sphingomyelin by oligodendrocytes--how and where?

Sphingomyelin (SM) biosynthesis in cultured oligodendrocytes (OC) was evaluated: (i) with [14C] tracers (choline, ethanolamine, serine) to pinpoint the major metabolic routes; (ii) with fluorescent and truncated, radiolabeled ceramide analogs to determine the relative activities of SM-synthase in intra-and extra-Golgi compartments of OC. In contrast to a general contention in the literature that SM synthase is absent from the brain, our data show that (choline-->CDP-choline-->phosphatidylcholine (PC)-->SM) is the major anabolic route with only a minor contribution to PC via methylation of phosphatidylethanolamine (PE). SM synthase activity was found to be equally divided between intra- and extra-Golgi compartments of OC. Moreover, significant SM-synthase activity was recovered in purified myelin preparations. Our results shed new light on the possible involvement of sphingolipid-derived mediators in myelination.

Synthesis of non-hydroxy-galactosylceramides and galactosyldiglycerides by hydroxy-ceramide galactosyltransferase

Galactosylceramide (GalCer) is the major glycolipid in brain. In order to characterize the activity of brain UDPgalactose: ceramide galactosyltransferase (CGalT), it has been stably expressed in CGalT-negative Chinese hamster ovary (CHO) cells. After fractionation of transfected cells, CHO-CGT, on sucrose gradients, the activity resides at the density of endoplasmic reticulum and not of Golgi. A lipid chromatogram from CHO-CGT cells revealed two new iodine-staining spots identified as GalCer, since they comigrate with GalCer standards, can be metabolically labelled with [3H]galactose, are recognized by anti-GalCer antibodies, and are resistant to alkaline hydrolysis. A third [3H]galactose lipid was identified as galactosyldiglyceride. In the homogenate CGalT displays a 25-fold preference for hydroxy fatty acid-containing ceramides. Remarkably, endogenous GalCer of transfected cells contains exclusively non-hydroxy fatty acids: fast atom bombardment and collision-induced dissociation mass spectrometric analysis revealed mainly C16:0 in the lower GalCer band on TLC and mainly C22:0 and C24:0 in the upper band. Our results suggest that CGalT galactosylates both hydroxy- and non-hydroxy fatty acid-containing ceramides and diglycerides, depending on their local availability. Thus, CGalT alone may be responsible for the synthesis of hydroxy- and non-hydroxy-GalCer, and galactosyldiglyceride in myelin.

Fluctuation of the volume of distribution of amikacin and its effect on once-daily dosage and clearance in a seriously ill patient

OBJECTIVE

The main aim of the trial was to determine the extent to which the volume of distribution of amikacin fluctuates in a seriously ill patient receiving copious quantities of i.v. fluid over an extended term of treatment. The impact of the volume fluctuation on amikacin therapeutic peak concentrations was also assessed.

DESIGN AND SETTING

The case report describes a young, previously healthy male adult admitted to the surgical ICU of a teaching hospital following trauma to the head and central nervous system.

INTERVENTION

The patient received 1 g of amikacin once-daily i.v. for 35 consecutive days as part of an antimicrobial regimen. Blood samples were drawn for routine amikacin concentration determinations on 14 occasions, extending over the entire term of treatment, from which the required pharmacokinetic parameters were determined.

RESULTS

The volume of distribution of amikacin varied extensively from 0.27 to 0.61 l/kg (normal range 0.27 +/- 0.06 1/kg) notwithstanding the fact that amikacin clearance remained satisfactorily high throughout the term of treatment.

CONCLUSIONS

Once-daily therapeutic amikacin concentrations fluctuate extensively and rapidly in the seriously ill patient receiving copious quantities of i.v. fluids, despite competent renal function. The volume expansion seen in our patient is difficult to account for in terms of the extracellular fluid compartment only.

RECOMMENDATIONS

(a) Once-daily regimen amikacin peak concentrations should be frequently monitored in the seriously ill patient; (b) once-daily amikacin regimens are best monitored using blood specimens drawn at 1 and 6-8 h post administration.

An antiglycolipid antibody inhibits Madin-Darby canine kidney cell adhesion to laminin and interferes with basolateral polarization and tight junction formation

Epithelial cells polarize not only in response to cell-cell contacts, but also to contacts with a substratum composed of extracellular matrix molecules. To probe the role of specific matrix constituents in epithelial cell polarization, we investigated the effects of an adhesion-blocking mAb, 12B12, on initial polarization of MDCK cells. The 12B12 antibody, raised against whole MDCK cells, blocks adhesion to laminin by 65% but has no effect on adhesion of cells to collagen type I. Taking advantage of this antibody's function-blocking activity, as well as the fact that MDCK cells secrete laminin, the role of endogenous laminin in polarization was examined by plating cells on collagen-coated substrata in the presence of the antibody. Under these conditions, cell spreading was reduced 1.5h after plating, and cells were flatter and had fewer microvilli after 24 h. Even though lateral cell membranes were closely apposed, transepithelial resistance in the presence of the antibody was significantly reduced relative to controls. When the polarization of specific apical and basolateral markers was examined both biochemically and immunocytochemically in the presence of the antibody, we observed that the apical marker polarized at normal rates while basolateral markers did not. Surprisingly, the 12B12 antibody was not directed against any known cell adhesion protein but reacted specifically with Forssman antigen, a glycosphingolipid. These results suggest that glycolipids may play a significant role in cell adhesion via laminin and in epithelial cell polarization.

Topology of sphingolipid galactosyltransferases in ER and Golgi: transbilayer movement of monohexosyl sphingolipids is required for higher glycosphingolipid biosynthesis

Glucosylceramide (GlcCer) is synthesized at the cytosolic surface of the Golgi complex while enzymes acting in late steps of glycosphingolipid biosynthesis have their active centers in the Golgi lumen. However, the topology of the "early" galactose-transferring enzymes is largely unknown. We used short-chain ceramides with either an 2-hydroxy fatty acid (HFA) or a normal fatty acid (NFA) to determine the topology of the galactosyltransferases involved in the formation of HFA- and NFA-galactosylceramide (GalCer), lactosylceramide (LacCer), and galabiosylceramide (Ga2Cer). Although the HFA-GalCer synthesizing activity colocalized with an ER marker, the other enzyme activities fractionated at the Golgi density of a sucrose gradient. In cell homogenates and permeabilized cells, newly synthesized short-chain GlcCer and GalCer were accessible to serum albumin, whereas LacCer and Ga2Cer were protected. From this and from the results obtained after protease treatment, and after interfering with UDP-Gal import into the Golgi, we conclude that (a) GlcCer and NFA-GalCer are synthesized in the cytosolic leaflet, while LacCer and Ga2Cer are synthesized in the lumenal leaflet of the Golgi. (b) HFA-GalCer is synthesized in the lumenal leaflet of the ER, but has rapid access to the cytosolic leaflet. (c) GlcCer, NFA-GalCer, and HFA-GalCer translocate from the cytosolic to the lumenal leaflet of the Golgi membrane. The transbilayer movement of GlcCer and NFA-GalCer in the Golgi complex is an absolute requirement for higher glycosphingolipid biosynthesis and for the cell surface expression of these monohexosyl sphingolipids.

Sorting of newly synthesized galactosphingolipids to the two surface domains of epithelial cells

The high concentration of glycosphingolipids on the apical surface of epithelial cells may be generated by selective transport from their site of synthesis to the cell surface. Previously, we showed that canine kidney MDCK and human intestinal Caco-2 cells converted a ceramide carrying the short fluorescent fatty acid C6-NBD to glucosylceramide (GlcCer) and sphingomyelin (SM), and that GlcCer was preferentially transported to the apical surface as compared to SM. Here, we address the point that not all glycosphingolipid classes are apically enriched in epithelia. We show that a ceramide containing the 2-hydroxy fatty acid C6OH was preferentially converted by MDCK and Caco-2 cells to galactosylceramide (GalCer) and its derivatives galabiosylceramide (Ga2Cer) and sulfatide (SGalCer) as compared to SM and GlcCer--all endogenous lipid classes of these cells. Transport to the apical and basolateral cell surface was monitored by a BSA-depletion assay. In MDCK cells, GalCer reached the cell surface with two- to sixfold lower apical/basolateral polarity than GlcCer. Remarkably, in Caco-2 cells GalCer and GlcCer displayed the same apical/basolateral polarity, but it was sixfold lower for lipids with a C6OH chain than for C6-NBD lipids. Therefore, the sorting of a sphingolipid appears to depend on lipid structure and cell type. We propose that the different ratios of gluco- and galactosphingolipid synthesis in the various epithelial tissues govern lipid sorting in the membrane of the trans Golgi network by dictating the composition of the domains from where vesicles bud to the apical and basolateral cell surface.

Rigidity of dental local anaesthetic injection needles

The objective of this study was to determine the rigidity of 11 different types (4 brands) of dental local anaesthetic injection needles available in South Africa. Twenty needles of each type were attached to a Zwick material testing apparatus and subjected to pressure testing. Stress vs deformation curves were obtained for each needle. The data obtained was logarithmically converted and subjected to an analysis of covariance. The results from this study showed that there were statistically significant differences in the rigidity of dental needles available on the South African market.

The effect of baked areca nut extract on the growth of buccal mucosa fibroblasts from healthy non-areca nut chewers

Oral submucous fibrosis is a serious oral disease associated with the habit of chewing areca nut. The habit is relatively common among South Africans of Indian descent. The aim of this study was to observe the effect on growth of buccal mucosa fibroblasts derived from healthy individuals not practising the areca nut habit when the cells are exposed to nut extract. Fibroblast cell-lines from 6 individuals were grown in medium without extract and medium containing 50 and 100 [symbol: see text] g/ml extract of baked nut for 8 days. Cells not exposed to the nut extract behaved homogeneously. Reaction to the nut extracts, however, was dissimilar. The cells of 5 individuals showed no discernable reaction to the extracts while in one instance, the cells of a healthy adult male with no physical disabilities, showed marked growth inhibition. Thus, the finding indicates that when the effect of the nut or its constituents are tested on cells, it is necessary to use several cell-lines of the same cell type or a cell-line of which the growth parameters are standardized.

Prolonged diplopia following a mandibular block injection

A case is presented in which a 14-yr-old girl developed diplopia after injection of the local anesthetic Xylotox E 80 A (2% lidocaine with 1:80,000 epinephrine). Since the complication had a relatively slow onset and lasted for 24 hr, the commonly suggested explanations based on vascular, lymphatic, and neural route theories do not adequately fit the observations. No treatment, other than reassurance, was necessary, and the patient recovered fully.

The UDP-galactose:ceramide galactosyltransferase: expression pattern in oligodendrocytes and Schwann cells during myelination and substrate preference for hydroxyceramide

Galactosylceramide ("galactocerebroside"; GalC) is a major glycolipid in the myelin sheath of the CNS and the PNS. The enzyme UDP-galactose:ceramide galactosyltransferase (CGalT) catalyzes the final step of the synthesis of GalC: the transfer of galactose to ceramide. By a differential screening approach, we have isolated a cDNA, the sequence of which is identical to the recently isolated cDNA clones for CGalT. By nothern analysis and in situ hybridization we demonstrated that CGalT mRNA is expressed at birth in oligodendrocytes and Schwann cells, an expression pattern corresponding to the onset of myelination. In addition to the high expression levels of CGalT in oligodendrocytes and Schwann cells, in situ hybridization also showed expression in subtypes of neurons in spinal cord, cerebellum, and brain-stem in the adult CNS, but at a much lower level than in oligodendrocytes. Expression of CGalT in COS cells demonstrated that CGalT has a preference for hydroxyceramide as a substrate. CGalT-expressing COS cells synthesize and transport GalC to their cell surface as shown by immunofluorescence and by lipid analysis of living cells. Our results suggested that the CGalT specifically uses hydroxyceramide for the synthesis of GalC and that separate (co)enzymes are not needed.

Injection needles for dental local anesthesia

The implication of the physical characteristsof single-use disposable dental needles for administration local anesthetics, and the role of these properties in causing breakage, pain on injection, and morbidity in patients are reviewed in this article.

Sphingomyelin is synthesized at the plasma membrane of oligodendrocytes and by purified myelin membranes: a study with fluorescent- and radio-labelled ceramide analogues

In most cell types sphingomyelin is synthesized predominantly in the cis-medial compartments of the Golgi stacks whereas the contribution of the plasma membrane is much lower. The aim of this study was to assess the contribution of both compartments to the synthesis of sphingomyelin in myelinating cells. Therefore, oligodendrocytes from rat spinal cord were incubated in culture with fluorescently- or radiolabelled ceramides, and the effects of a block in the vesicular flow (monensin, brefeldin A, low temperature) on surface synthesis of sphingomyelin were evaluated. The results indicate that approximately 50% of the sphingomyelin synthase is present at the plasma and myelin membranes of oligodendrocytes.