Vascular applications of Spiral CT : an initial Experience

Since the clinical introduction of computed tomography (CT) in the mid 1970s, several technological and clinical advances have improved image quality and reduced scanning time. During the past decade technological breakthroughs have ushered in an exciting advance in medical imaging : spiral CT. Spiral CT technology with its high speed and volumetric data acquisition has spawned a new vascular imaging technique - spiral CT angiography which is noninvasive, accurate, faster and less expensive than conventional angiography. We report our experience of having performed 100 CT angiographies with 3-D reconstructions of various vascular territories of the body. Details of technique of data acquisition, methods of 3-D reconstruction and clinical applications are discussed.

Inhibition of benzoyl peroxide and ultraviolet-B radiation induced oxidative stress and tumor promotion markers by cycloartenol in murine skin

The chemopreventive potential of cycloartenol on benzoyl peroxide and UVB radiation-induced cutaneous tumor promotion markers and oxidative stress in murine skin is assessed. Benzoyl peroxide treatment (20 mg/animal/0.2 ml acetone) and UVB radiation (0.420 J/m(2)/s) caused a decrease in the activities of cutaneous antioxidant enzymes namely, catalase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, phase II metabolizing enzyme such as glutathione-S-transferase and quinone reductase and depletion in the level of cutaneous glutathione. There was also enhancement in cutaneous microsomal lipid peroxidation, xanthine oxidase activity, [(14)C]-ornithine decarboxylase activity and [(3)H]-thymidine incorporation into cutaneous DNA. Cycloartenol was topically applied prior to the application of benzoyl peroxide at dose levels of 0.2 mg and 0.4 mg/kg body weight in acetone, which resulted in significant inhibition of epidermal ornithine decarboxylase activity and DNA synthesis (P < 0.001). There was also significant reduction of lipid peroxidation and xanthine oxidase activity (P < 0.001). In addition, the depleted levels of glutathione, inhibited activities of antioxidant and phase II metabolizing enzymes, were also recovered to a significant level (P < 0.001). The data indicate that cycloartenol is an effective chemopreventive agent in skin carcinogenesis.

Nerve growth factor-induced protein kinase C stimulation contributes to TrkA-dependent inhibition of p75 neurotrophin receptor sphingolipid signaling

Previous studies have established that reciprocal interactions between the low-affinity p75 nerve growth factor (NGF) receptor (p75(NTR)) and the high-affinity TrkA NGF receptor can dictate the cellular response to NGF. As the most important interaction, TrkA signaling was found to inhibit p75(NTR)-mediated sphingomyelinase (SMase) stimulation, ceramide production, and apoptosis. However, the mechanism by which TrkA counteracts p75(NTR)-coupled sphingolipid signaling is still unclear. Considering the stimulatory effect of NGF on protein kinase C (PKC) activity, we investigated the role of PKC in TrkA/p75(NTR) signaling interaction. In this study, we found that, in SK-N-BE cells, which selectively express p75(NTR), phorbol ester-induced PKC stimulation resulted in the abrogation of SMase stimulation and ceramide production induced by NGF. Moreover, in SK-N-BE neuroblastoma cells, which selectively express TrkA, NGF stimulated global PKC activity through two independent pathways involving phospholipase Cgamma (PLCgamma) and phosphoinositide-3 kinase (PI3K). In SH-SY5Y, another neuroblastoma cell line, which coexpresses TrkA and p75(NTR), NGF induced PKC stimulation through a TrkA/PI3K signaling pathway, whereas there was no ceramide production. However, in these cells, the inhibition of TrkA, PI3K, and PKC resulted in the restoration of NGF-induced ceramide production. Thus, our study demonstrates for the first time that TrkA interferes with p75(NTR) signaling through a PI3K/PKC-dependent mechanism.

Inhibition of cutaneous oxidative stress and two-stage skin carcinogenesis by Hemidesmus indicus (L.) in Swiss albino mice

Chemopreventive potential of H. indicus on 7,12-dimethyl-benz[a]anthracene (DMBA)-initiated and 12-O-tetradecanoyl 13-phorbol acetate (TPA) promoted murine skin carcinogenesis has been assessed. Topical application of H. indicus resulted in significant protection against cutaneous tumorigenesis. Topical application of plant extract prior to that of TPA resulted in significant inhibition against TPA-caused induction of epidermal ornithine decarboxylase (ODC) activity and DNA synthesis. Application of H. indicus at a dose level of 1.5 and 3.0 mg/kg body weight in acetone prior to that of TPA treatment resulted in significant inhibition of oxidative stress. The level of lipid peroxidation was significantly reduced. In addition, depleted levels of glutathione and reduced activities of antioxidant enzymes were restored respectively). The results indicate that H. indicus is a potent chemopreventive agent in skin carcinogenesis.

3-D Spiral Computerised Tomographic Angiography in Evaluation of Potential Renal Donors

A total of 30 potential renal donors aged between 35 and 50 years were subjected to pre-operative 3-Dimensional Spiral Computerised Tomography (CT) angiography with the aim to assess its efficacy in the evaluation of renal vasculature. The investigations were carried out on a Philips Tomoscan AV Spiral CT scanner. Scan parameters included a collimation of 3 mm and table speed of 4 mm/sec. A total of 120 ml of non-ionic contrast was injected at a rate of 4 ml per second using a power injector. The axial images obtained were reconstructed at 2mm intervals and 3-D reconstruction was done using Surface Shaded Display (SSD) and Maximum Intensity Projection (MIP) protocols. CT angiography and its correlation with per-operative findings revealed 97 to 100% sensitivity and specificity in identifying the main and accessory renal arteries and veins. The angiogram also excluded the presence of pathologies like polycystic kidney, horse shoe kidney with a thick isthmus and occult renal cell carcinoma that would prevent the patient from being a donor. 3-D spiral CT angiography allows the radiologist to provide the transplant surgeon with precise pre-operative anatomy of the renal vasculature thus reducing the risks and complications associated with the harvesting procedure and increasing the chances of a successful outcome. Thus it is a fast, accurate, inexpensive and minimally invasive procedure that is becoming the modality of choice for the pre-operative evaluation of potential renal transplant donors.

Modulation of biochemical parameters by Hemidesmus indicus in cumene hydroperoxide-induced murine skin: possible role in protection against free radicals-induced cutaneous oxidative stress and tumor promotion

Hemidesmus indicus has been shown to possess significant activity against immunotoxicity and other pharmacological and physiological disorders. In this communication, we have shown the modulating effect of H. indicus on cumene hydroperoxide-mediated cutaneous oxidative stress and tumor promotion response in murine skin. Cumene hydroperoxide treatment (30 mg per animal) increased cutaneous microsomal lipid peroxidation and induction of xanthine oxidase activity which are accompanied by decrease in the activities of cutaneous antioxidant enzymes and depletion in the level of glutathione. Parallel to these changes a sharp decrease in the activities of phase II metabolizing enzymes was observed. Cumene hydroperoxide treatment also induced the ornithine decarboxylase activity and enhanced the [3H]-thymidine uptake in DNA synthesis in murine skin. Application of ethanolic extract of H. indicus at a dose level of 1.5 and 3.0mg/kg body weight in acetone prior to that of cumene hydroperoxide treatment resulted in significant inhibition of cumene hydroperoxide-induced cutaneous oxidative stress, epidermal ornithine decarboxylase activity and enhanced DNA synthesis in a dose-dependent manner. Enhanced susceptibility of cutaneous microsomal membrane for lipid peroxidation and xanthine oxidase activity were significantly reduced (P<0.01). In addition the depleted level of glutathione, inhibited activities of antioxidants and phase II metabolizing enzymes were recovered to significant level (P<0.05). In summary, our data suggest that H. indicus is an effective chemopreventive agent in skin and capable of ameliorating hydroperoxide-induced cutaneous oxidative stress and tumor promotion.

Distribution of T4 TSH values in children--the Shifa experience

OBJECTIVE

To evaluate the distribution of Thyroxin (T4) and Thyroid Stimulating Hormone (TSH) values in children of various age groups attending our hospital.

METHOD

We have retrospectively reviewed the T4, TSH levels recorded at our hospital in children from birth to 5 years and evaluated the reference intervals for T4 TSH amongst different ages. Non parametric methods were used to establish a 97.5th, 95th, 50th, 5th and 2.5th centiles.

RESULTS

In T4 (n=1148) and TSH (n=1142) samples reviewed a TSH surge following delivery showed a sharp decline in the first 4 days of life. This was followed by a more gradual downward trend. Data on T4 estimations showed a similar but more gradual downward trend in advancing age groups. The 5th-95th centile reference range for TSH showed values between 1.7-22.5 (0-4 days; n=992), 0.6-13.3 (5-7 days; n=38), 0.9-14.0 (1 week-1 month; n=38), 0.5-13.6 (1 month-1 year, n=38) and 0.4-12.8 (1-5 years; n=38) microlU/mL. The 5th-95th centile reference range for T4 showed values between 10.7-25.0 (0-4 days; n=995), 6.5-20.4 (5-7 days; n=35), 8.0-18.1 (1 week-1 month; n=38), 6.0-16.1 (1 month-1 year; n=41), 6.9-15.3 (1-5 years; n=39) micro gm/dl.

CONCLUSION

We recommend using separate T4 and TSH reference values for children in different age groups. Further large-scale studies should be done in Pakistan to establish these reference values within age groups. A national center for neonatal thyroid screening is highly recommended.

Chemopreventive effect of Vitis vinifera extract on 12-O-tetradecanoyl-13-phorbol acetate-induced cutaneous oxidative stress and tumor promotion in murine skin

Vitis vinifera (grapes) is used as a fruit worldwide and known for its pharmacological properties. The present paper assesses the chemopreventive potential of Vitis vinifera against 12-O-tetradecanoyl-13-phorbol acetate (TPA)-mediated tumor promotion in 7,12-dimethyl-benz[a]anthracene (DMBA) initiated mice skin. Skin tumor initiation was achieved by a single topical application of DMBA (40 microg/animal/0.20 ml acetone) to mice. Two weeks after the initiation, promoting agent, TPA (5.0 microg/animal/0.2 ml acetone) was applied two times a week for 20 weeks. Pretreatment of Vitis vinifera 1h prior to each application of TPA resulted in protection against cutaneous tumorigenesis in dose-dependent manner. This inhibition was evident when tumor data was considered as the percentage of mice with tumor and the number of tumors per mouse. We have shown that typical application of Vitis vinifera prior to that of TPA resulted in significant inhibition against TPA-caused induction of epidermal ODC activity (P<0.001) and DNA synthesis. Application of Vitis vinifera at a dose level of 5.0 mg and 10.0 mg kg(-1) body weight in acetone prior to that of TPA treatment resulted in partial significant inhibition of oxidative stress in dose-dependent manner. The concomitant increase in the microsomal lipid peroxidation and xanthine oxidase activities were significantly reduced (P<0.001). In addition, the depleted level of glutathione and inhibited activities of antioxidant enzymes were recovered to the partial significant level. Hence, it can be suggested that Vitis vinifera can be used as a chemopreventive agent against oxidative stress and carcinogenesis.

HIV-1 protease processes procaspase 8 to cause mitochondrial release of cytochrome c, caspase cleavage and nuclear fragmentation

Infection of T cells with HIV-1 induces apoptosis and modulates apoptosis regulatory molecules. Similar effects occur following treatment of cells with individual HIV-1 encoded proteins. While HIV-1 protease is known to be cytotoxic, little is known of its effect on apoptosis and apoptosis regulatory molecules. The ability of HIV-1 protease to kill cells, coupled with the degenerate substrate specificity of HIV-1 protease, suggests that HIV-1 protease may activate cellular factor(s) which, in turn, induce apoptosis. We demonstrate that HIV-1 protease directly cleaves and activates procaspase 8 in T cells which is associated with cleavage of BID, mitochondrial release of cytochrome c, activation of the downstream caspases 9 and 3, cleavage of DFF and PARP and, eventually, to nuclear condensation and DNA fragmentation that are characteristic of apoptosis. The effect of HIV-1 protease is not seen in T cell extracts which have undetectable levels of procaspase 8, indicating a specificity and requirement for procaspase 8.

Correlation of Helicobacter pylori in dental plaque and gastric mucosa of dyspeptic patients

OBJECTIVE

To establish the prevalence of Helicobacter pylori colonization of dental plaque and its correlation with Helicobacter pylori infection of the antral mucosa in patients with symptomatic dyspepsia.

METHODS

Seventy eight adult dyspeptic patients undergoing upper gastrointestinal tract endoscopy were prospectively enrolled. Four air dried dental plaque cytology slides and four gastric antral mucosal biopsies were stained with Giemsa stain. CLO test was used for detection of urease activity of Helicobacter pylori in the dental plaque specimens and antral mucosal biopsies. Data on endoscopic findings and orodental hygiene were recorded.

RESULTS

Dental plaque colonization using CLO test and cytology was found to be 100% and 88% respectively. Antral biopsy for H. pylori was positive in 61% cases by CLO test and 57% cases on histopathology. Forty four out of 69 patients (63%) had both dental plaque and antral biopsy positive for H. pylori. No patient with negative dental plaque cytology was positive for H. pylori in gastric mucosa. A statistically significant correlation was found between H. pylori colonization of dental plaque and gastric antrum. The sensitivity and specificity of dental plaque cytology in diagnosing H. pylori antral colonization was 100% and 26% while the positive and negative predictive values were 64% and 100% respectively.

CONCLUSION

The prevalence of H. pylori in dental plaque of patients with dyspepsia was very high in our patients indicating it to be a major reservoir of infection.

Carpal tunnel syndrome despite negative neurophysiological studies

The purpose of the present study was to compare the results of conservative and operative treatment for patients with carpal tunnel syndrome having normal neurophysiological studies. We studied 125 patients with normal neurophysiological studies and analysed eight symptoms and signs as "prognostic factors". Ninety-six patients were treated conservatively (splintage, steroid injection, antiinflammatory medications, activity modification) and 29 were treated surgically (open decompression). One year after initiation of treatment we assessed the outcome and statistically analysed (chi-square test) the differences between the two groups. We did not find any statistically significant correlation between "prognostic factors" and outcome. Twenty four percent of the group treated non-operatively had a good or excellent outcome, whereas 90% of the group treated operatively had a good or excellent outcome. This difference was statistically significant (p < 0.0001). Our study supports the view that the diagnosis of carpal tunnel syndrome is clinical and not neurophysiological. We now recommend operative treatment for these patients.

Neonatal thyroid screening--the Shifa experience

OBJECTIVE

To evaluate the results of T4, TSH analysis and pattern of presentation in babies born at our hospital.

METHOD

We retrospectively reviewed the data collected from T4, TSH screening on all babies delivered at our Hospital, where the blood was drawn within the first 4 days of life. Period under evaluation was from October 1995 to October 1998. Shifa Reference values were used.

RESULTS

Blood sample were collected from 997 babies within 4 days of birth. Nine hundred and forty nine (95.2%) were evaluated after 24 hours. and 48(4.8%) in less than 24 hours of age. A high TSH was reported on 166 (16.8%) babies and a low T4 was reported on 78 (7.9%) babies. Statistical analysis showed a similar sensitivity for T4 and TSH (100%) but a higher specificity for T4 (93.1%) as compared to TSH (86%). A high-TSH with a low T4 was reported in 5 (0.5%) babies out of which 1 case was confirmed as congenital hypothyroidism requiring permanent thyroxin replacement and one case manifested a picture consistent with transient hypothyroidism. A low TSH with a low T4 was seen in 2 cases, however, they were all premature babies on antibiotics.

CONCLUSION

Congenital hypothyroidism may be more frequent in our population and for the purpose of screening babies T4 values would carry a higher positive predictive value than TSH. Combining T4 TSH assays would however reduce the call back rate quite significantly but may prove to be a bit more expensive.

A method for measuring particle number emissions from vehicles driving on the road

Earlier research has demonstrated that the conditions of dilution of engine exhaust gases profoundly influence the size distribution and total number of particles emitted. Since real world dilution conditions are variable and therefore difficult to simulate, this research has sought to develop and validate a method for measuring particle number emissions from vehicles driving past on a road. This has been achieved successfully using carbon dioxide as a tracer of exhaust gas dilution. By subsequent adjustment of data to a constant dilution factor, it is possible to compare emissions from different vehicles using different technologies and fuels based upon real world emission data. Whilst further optimisation of the technique, especially in terms of matching the instrument response times is desirable, the measurements offer useful insights into emissions from gasoline and diesel vehicles, and the substantial proportion of particles emitted in the 3-7 nanometre size range.

Comparison of PCR method with the culture method for identification of gonococci from endocervical swabs

Gonococcal infection remains still a major cause of morbidity among sexually active individuals. Diagnosis of the infection in a female case is more difficult than that in a male. This was a prospective study among 269 female commercial sex workers (CSWs) to screen them for gonococcal infection, comparing the rapid method of identification of gonococci by polymerase chain reaction (PCR) with the selective culture method. A total of 92 (34.2%) CSWs were identified positive for Neisseria gonorrhoeae by combination of the two methods. The PCR method identified 87 of the specimens to harbour cppB gene of N. gonorrhoeae, whereas culture method identified 83 specimens showing colonies of gonococci. Taking into consideration of the total positive cases (92), the PCR method showed a sensitivity of 94.57%, whereas sensitivity of culture method was 90.22%. The selective culture method appears to be the most applicable in the identification of gonococci from clinical specimens, particularly in the less resourceful countries like Bangladesh.

Role of positive charge of lysine residue on ribosome-inactivating property of gelonin

The report that gelonin cross-linked with monoclonal antibodies with the use of 2-iminothiolane (2-IT) exhibited higher cytotoxicity than the conjugates prepared with the use of N-succinimidyl-3-(2-pyridylthio) propionate (SPDP) alone, has prompted us to investigate the effect of epsilon-NH2 group modification with 2-IT on the ribosome-inactivating property (RIP) of gelonin. The purified gelonin was modified with 2-IT at a different molar ratio and their effects on immunoreactivity and ribosome-inactivating property were compared with those of N-succinimidyl 6-[3-(2-pyridyldithio) propionamido] hexanoate (long chain-SPDP) and SPDP modified gelonin derivatives. Modification of single amino group with 2-IT results in about 25-50% inhibition of immunoreactivity and 60-70% loss of protein synthesis inhibition activity. Modification of 2-3 amino groups further hampers both immunoreactivity and protein synthesis inhibition property of gelonin. Both the long chain-SPDP with SPDP modifications showed more pronounced effects on immunoreactivity and RIP activity as compared to the similar ratio of 2-IT modification(s). It may, therefore, be concluded that the positive charge plays an important role in the immunological as well as the protein synthesis inhibitory effect of gelonin.

Dialyzer reuse impact on dialyzer efficiency, patient morbidity and mortality and cost effectiveness

Since the introduction of dialyzer reuse more than three decades ago, several studies have reported its safety, efficacy and cost effectiveness. Reuse of hemodialyzer was prospectively studied in ten chronic hemodialysis (HD) patients recruited from the renal unit, the King Khalid University Hospital, Riyadh, Saudi Arabia, for three months. During the study period, 66 dialyzers were used for 408 sessions of HD, with a mean reuse of 6.2 +/- 5.3 episodes per dialyser, the mean of maximum reuse episodes being 13.7 +/- 8.0. The urea reduction ratio was maintained between 73 +/- 5% at baseline to 71.2 +/- 9.03% (p=0.53) at the maximum reuse. Similarly phosphate reduction with each HD session was maintained; mean decrease in phosphate levels was 0.67 mmol/L. Significant increase in heparin requirement was noted; however, the risk of bleeding was not increased. Hematocrit levels increased from 30.4 +/- 4.1% to 33.2 +/- 3.6% at the end of the study (p=0.6). Albumin leak in dialysate decreased with each reuse; baseline 8.27 +/- 7.93 mg/L to 2.8 +/- 0.4 mg/L at maximum reuse (p=0.04). Serum albumin levels remained stable. No short-term adverse effects on patients' morbidity and mortality were noted. Total cost savings of 53% was achieved with the reuse of dialyzers, excluding capital equipment used for preparation for reuse. In conclusion, dialyzer reuse seems to be safe and may provide an economical and efficient dialysis. Studies involving larger number of patients is required to validate this observation.

Tephrosia purpurea ameliorates N-diethylnitrosamine and potassium bromate-mediated renal oxidative stress and toxicity in Wistar rats

In an earlier communication, we have shown that Tephrosia purpurea ameliorates benzoyl peroxide-induced oxidative stress in murine skin (Saleem et al. 1999). The present study was designed to investigate a chemopreventive efficacy of T purpurea against N-diethylnitrosamine-initiated and potassium bromate-mediated oxidative stress and toxicity in rat kidney. A single intraperitoneal dose of N-diethylnitrosamine (200 mg/kg body weight) one hr prior to the dose of KBrO3 (125 mg/kg body weight) increases microsomal lipid peroxidation and the activity of xanthine oxidase and decreases the activities of renal antioxidant enzymes viz., catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase, phase II metabolizing enzymes such as glutathione-S-transferase and quinone reductase and causes depletion in the level of renal glutathione content. A sharp increase in blood urea nitrogen and serum creatinine has also been observed. Prophylactic treatment of rats with T. purpurea at doses of 5 mg/kg body weight and 10 mg/kg body weight prevented N-diethylnitrosamine-initiated and KBrO3 promoted renal oxidative stress and toxicity. The susceptibility of renal microsomal membrane for iron ascorbate-induced lipid peroxidation and xanthine oxidase activities were significantly reduced (P<0.01). The depleted levels of glutathione, the inhibited activities of antioxidant enzymes, phase II metabolizing enzymes and the enhanced levels of serum creatinine and blood urea nitrogen were recovered to a significant level (P<0.01). All the antioxidant enzymes were recovered dose-dependently. Our data indicate that T purpurea besides a skin antioxidant can be a potent chemopreventive agent against renal oxidative stress and carcinogenesis induced by N-diethylnitrosamine and KBrO3.