Spinal cord stimulation modulates intraspinal colorectal visceroreceptive transmission in rats

Previous studies have shown that spinal cord stimulation (SCS) of upper lumbar segments decreases visceromotor responses to mechanical stimuli in a sensitized rat colon and reduces symptoms of irritable bowel syndrome in patients. SCS applied to the upper cervical spinal dorsal column reduces pain of chronic refractory angina. Further, chemical stimulation of C1-C2 propriospinal neurons in rats modulates the responses of lumbosacral spinal neurons to colorectal distension. The present study was designed to compare the effects of upper cervical and lumbar SCS on activity of lumbosacral neurons receiving noxious colorectal input. Extracellular potentials of L6-S2 spinal neurons were recorded in pentobarbital anesthetized, paralyzed and ventilated male rats. SCS (50 Hz, 0.2 ms) at low intensity (90% of motor threshold) was applied to the dorsal column of upper cervical (C1-C2) or upper lumbar (L2-L3) ipsilateral spinal segments. Colorectal distension (CRD, 20 mmHg, 40 mmHg, 60 mmHg, 20s) was produced by air inflation of a latex balloon. Results showed that SCS applied to L2-L3 and C1-C2 segments significantly reduced the excitatory responses to noxious CRD from 417.6+/-68.0 to 296.3+/-53.6 imp (P<0.05, n=24) and from 336.2+/-64.5 to 225.0+/-73.3 imp (P<0.05, n=18), respectively. Effects of L2-L3 and C1-C2 SCS lasted 10.2+/-1.9 and 8.0+/-0.9 min after offset of CRD. Effects of SCS were observed on spinal neurons with either high or low-threshold excitatory responses to CRD. However, L2-L3 or C1-C2 SCS did not significantly affect inhibitory neuronal responses to CRD. C1-C2 SCS-induced effects were abolished by cutting the C7-C8 dorsal column but not by spinal transection at cervicomedullary junction. These data demonstrated that upper cervical or lumbar SCS modulated responses of lumbosacral spinal neurons to noxious mechanical stimulation of the colon, thereby, proved two loci for a potential therapeutic effect of SCS in patients with irritable bowel syndrome and other colonic disorders.

Cellular automata and its advances to drug therapy for HIV infection

This paper gives an over view of the use of cellular automata (CA) model of drug therapy for HIV infection. Nonuniform CA is employed to simulate drug treatment of HIV infection, where each computational domain may contain different CA rules, in contrast to normal uniform CA models. Ordinary (or partial) differential equation models are insufficient to describe the two extreme time scales involved in HIV infection (days and decades), as well as the implicit spatial heterogeneity. Zorzenon and Coutinho [Phy Rev Lett, 16 (2001) 1] reported a cellular automata approach to simulate three-phase patterns of human immunodeficiency virus (HIV) infection consisting of primary response, clinical latency and onset of acquired immunodeficiency syndrome (AIDS). But here we present a related model, based on non-uniform CA to study the dynamics of drug therapy of HIV infection. The main aim in this model is to simulate the four phases (acute, chronic, drug treatment responds and onset of AIDS). The results shown here indicate that both simulations (with and without treatments) evolve to the relatively same steady state (characteristics of Wolfram's class II behavior). Different kinds of drug therapies can also be simulated in this model, which can be found useful for developing a proper drug therapy.

Surface-reconstruction-switched adsorbate photofragmentation dynamics

Energy-resolved angular distributions of neutral fragments ejected during photoinduced electron transfer reaction of CH3Br on GaAs(100) exhibit three distinct methyl-radical ejection channels. These undergo marked changes when the termination is switched from the Ga-rich c(8 x 2) to the As-rich c(2 x 8). Our observations are consistent with a strong adsorption-site dependence of the dynamics.

Hepatitis B vaccination among health care workers and students of a medical college

OBJECTIVE

To study the vaccination status against Hepatitis B among health care workers and students of a medical school.

MATERIALS AND METHODS

It is a descriptive study done at Allama Iqbal Medical College, Lahore. The participants comprised of 206 health care workers of various categories and 327 medical students. The main outcome measure was vaccination status and reasons for non-vaccination.

RESULTS

Only 49% health care workers and 42.20% medical students were vaccinated. The main reasons for non-vaccination (47.7%) among health care workers was the high cost of vaccination, while the most often cited reason (33.7%) among medical student was the belief that they were not at risk. This belief was also prevalent among nurses (36.4%), laboratory workers (38.6%) and paramedics (33.2%).

CONCLUSION

In a low-income country like Pakistan the health institutions should bear the cost for vaccinating their staff. Efforts should also be made to impart appropriate health education regarding hepatitis B infection.

Pulmonary function profile in chronic congestive heart failure and the effect of ipratropium bromide

Twenty-five symptomatic patients of chronic heart failure were subjected to spirometry to detect abnormalities of pulmonary function and to assess the effect of ipratropium bromide in reversing or minimising these abnormalities. All the patients exhibited abnormal pulmonary function manifesting as obstructive (15/25) or restrictive (10/25) ventilatory defect. There was overall improvement in lung functions with ipratropium bromide especially in those with obstructive ventilatory defects and mostly comprised of smokers. Forced expiratory volume in one second increased by 47.7 percent (p < 0.02), forced expiratory volume in one second/forced vital capacity ratio by 14.1 percent (p < 0.001) and maximal voluntary ventilation by 40.6 percent (p < 0.05) in these patients. It is concluded that ipratropium bromide can prove as a promising adjunctive therapeutic intervention in improving quality of life in patients of chronic congestive heart failure who are incapacitated by dyspnoea and have clearly documented ventilatory defects.

Development and evaluation of a multiple-unit oral sustained release dosage form for S(+)-ibuprofen: preparation and release kinetics

Mini-matrix tablets containing S(+)-ibuprofen have been prepared by the wet granulation method. The hydrophilic matrix was formed with either xanthan gum, karaya gum or hydroxymethylcellulose (HPMC) together with a choice of additives from lactose, Encompress(R), Avicel(R) PH101, talc and Lubritab(R). Multiple unit dosage forms (MUDFs) were subsequently obtained by encapsulating the mini-matrix tablets into hard gelatin capsules. Preparation, in vitro release profiles and release kinetics are presented.

Silent myocardial ischemia and cardiac autonomic neuropathy in diabetics

OBJECTIVE

To evaluate the association of silent myocardial ischemia (SMI) with cardiac autonomic neuropathy in asymptomatic diabetic patients.

MATERIAL AND METHODS

Two hundred asymptomatic patients of diabetes mellitus were assessed for evidence of cardiac autonomic neuropathy. Of these, 30 (15 males, 15 females; mean age 44.7 +/- 8.8 years) were found to have cardiac autonomic neuropathy. Thirty (30) age and sex matched diabetic patients (mean age 42.4 +/- 7.6 years) who had no evidence autonomic neuropathy were included in the study as control group. Both the groups of patients were evaluated for SMI by 24 hour ambulatory electrocardiographic (ECG) monitoring.

RESULTS

Incidence of SMI was significantly higher in patients with autonomic neuropathy 12/30 (40%) compared to those without 3/30 (10%) p < 0.001. Duration of diabetes was more (13 +/- 1.59 years) in patients with autonomic neuropathy compared to the control group (8.66 +/- 1.55 years) p < 0.001. Serum cholesterol and triglyceride levels were significantly higher in patients with autonomic neuropathy in comparison to control group < 0.05 and < 0.01, respectively. There was no difference in the pattern of SMI in the two groups (p = N.S).

CONCLUSION

Cardiac autonomic neuropathy predisposes patients with diabetes mellitus to SMI. Twenty four hour ambulatory ECG monitoring provides useful diagnostic information in early detection and evaluation of SMI in asymptomatic diabetic patients.

Comparative mutagenic and genotoxic effects of three antimalarial drugs, chloroquine, primaquine and amodiaquine

Comparative mutagenic and genotoxic effects of three antimalarial drugs, chloroquine, primaquine and amodiaquine, were assessed in the Ames mutagenicity assay (in strains TA97a, TA100, TA102 and TA104) and in vivo sister chromatid exchange (SCE) and chromosome aberration (CA) assays in bone marrow cells of mice. These are the most commonly used antimalarial drugs available at present throughout the world. The results of the bacterial mutagenicity assays showed a very weak mutagenic effect of all three drugs in Salmonella strains TA97a and TA100 both with and without S9 mix and in TA104 only with S9 mix. The results of the in vivo SCE and CA assays indicate that these three drugs are genotoxic in bone marrow cells of mice.

Clinical spectrum of infective endocarditis: 15 years experience

Four hundred and sixty-six patients (277 males, 189 females; mean age 23.2 years) diagnosed as cases of infective endocarditis during the past 15 years were retrospectively analysed. Two-thirds of patients belonged to the 15 to 35 years age group. The most common predisposing cardiac lesion was rheumatic heart disease seen in 73.4 percent patients. Mitral valve prolapse and right-sided endocarditis were infrequent, seen in four patients each. Blood culture positivity was 28.7 percent in adults and 61 percent in children. Commonest organism isolated was staphylococcus aureus in adults (39.3%) and streptococcus viridans in children (48%). Salmonella typhi was detected in 17 patients and showed excellent response to ciprofloxacin and gentamycin. Overall mortality was 13.9 percent and resistant heart failure was the leading cause of death. Our study presents the clinical spectrum of infective endocarditis and highlights the comparison with western studies.

Relationship between swelling, erosion and drug release in hydrophillic natural gum mini-matrix formulations

The swelling, erosion and solvent front penetration properties of mini-matrices containing xanthan (X), locust bean (LB) and karaya (K) gums were examined, analysed and related to the overall in vitro release kinetics of diclofenac sodium, used as a model drug. Mini-matrices were produced with drug:gum ratios of 1:1 as well as formulations of drug and X in combinations of 2:1, 2:3 and 1:2. The rank order of decreasing swelling index (SI) in both axial and radial dimensions was X?K?LB and each gum showed almost Fickian swelling behaviour. The solvent front penetration rates were consistent with the rates of swelling. However, the order of decreasing drug release and erosion rates was LB>X>K and all formulations demonstrated anomalous (non-Fickian) drug release kinetics. Therefore Fickian drug diffusion and polymer erosion were both occurring simultaneously. The dominant mechanism depended on the nature and content of the gum, as well as the stage in the dissolution time period. There was a loss of matrix integrity in formulations containing a high drug:gum ratio.

Comparative mutagenic and genotoxic effects of three propionic acid derivatives ibuprofen, ketoprofen and naproxen

The mutagenicity of three propionic acid derivatives, namely ibuprofen, ketoprofen and naproxen, was tested in the Ames mutagenicity assay (in strains TA97a, TA100 and TA102) and in vivo genotoxicity was tested by sister chromatid exchange (SCE) in bone marrow cells of mice. These are the anti-inflammatory drugs frequently used in different parts of the world. Mutagenicity results showed no mutagenic effects in strains TA97a, TA100 and TA102 for all three drugs. Results of in vivo SCE assays indicate that these three drugs are weakly genoxic in bone marrow cells of mice. This is the first report of the Ames mutagenicity assay for ketoprofen and in vivo SCE assay for three drugs.

Acetates and benzoates of alkyl catechols and evaluation of their antibacterial activity

Potential biologically active alkyl catechol esters were prepared and their antibacterial activity was determined against 12 Gram-positive and 16 Gram-negative bacteria. Esterification (acetylation and benzoylation) of mono-, di- and tetra- substituted alkyl catechols afforded the di-acetyl and di-benzoyl derivatives in each case. In the primary screening it was observed that the substitution of hydroxyl group in alkyl catechol with an acyl group generally resulted in a decrease of antibacterial activity. A number of acetyl and benzoyl derivatives inhibited the growth of Salmonella typhi. In case of Gram-positive bacteria only di-O-benzoyl-3,5,6,-tetra-(3-hexyl) catechol (26) showed a significant activity.

Comparative study of 18 gauge and 20 gauge intravenous catheters during transcranial Doppler ultrasonography with saline solution contrast

A formal technical protocol has not been established for transcranial Doppler ultrasonography in the detection of venous to arterial shunts; techniques have been adapted from contrast echocardiography. We evaluated the effect of different diameter indwelling intravenous catheters on the detection of right-to-left shunts by transcranial Doppler ultrasonography. Fifteen patients underwent transcranial Doppler sonographic evaluation with saline solution contrast using both 18 gauge and 20 gauge indwelling intravenous catheters. The larger bore intravenous catheter delivered a greater number of signals in a shorter time to the insonated middle cerebral artery. We recommend that a standardized method for transcranial Doppler sonographic contrast studies include an 18 gauge intravenous catheter.

Chemistry and biological activity of a tryptamine and beta-carboline series of bases

Twenty-six derivatives of harmaline and tetrahydroharmine were prepared and characterized by UV, IR, MS, and NMR spectroscopy. They were tested for their antimicrobial, antiplatelet aggregation and cytotoxic activity. Their effect on central nervous system was also studied.

Transcranial Doppler ultrasonography in the detection of venous to arterial shunting in acute stroke and transient ischaemic attacks

OBJECTIVES

To prospectively evaluate the prevalence of venous to arterial shunting in patients with acute stroke and transient ischaemic attacks (TIAs) using transcranial Doppler ultrasonography (TCD) with saline contrast.

METHODS

A consecutive series of patients with stroke or TIA underwent contrast TCD. Patients were subsequently divided into groups according to causative factors for stroke or TIA. The prevalence of right to left shunt was assessed within these groups.

RESULTS

A total of 210 patients underwent contrast TCD. A right to left shunt was detected in 28.6% of patients (60 of 210). Among the patients with cryptogenic stroke or TIA, 37.1% (43 of 116) had a positive contrast TCD whereas only 18% (17 of 94) with another identifiable cause had a positive test (P = 0.0024). When age was used to further classify those patients with cryptogenic stroke, TCD was positive in 59.3% patients (16 of 27) of < or = 50 years of age versus 30.3% of patients (27 of 89) > 50 years of age (P = 0.0058).

CONCLUSIONS

There was a significantly higher prevalence of venous to arterial shunting in patients with stroke or TIA of undetermined cause than in stroke patients with identifiable aetiologies, as detected by contrast TCD. The prevalence of a venous to arterial shunt was significantly higher in the younger group with cryptogenic stroke. Saline contrast TCD is a relatively non-invasive bedside procedure useful in the detection of venous to arterial shunting.

Comparative genotoxicity of six salicylic acid derivatives in bone marrow cells of mice

In vivo sister chromatid exchange (SCE) and chromosome aberrations (CA) were carried out for six salicylic acid derivatives in bone marrow cells of mice. Six salicylic acid derivatives, namely acetyl salicylic acid (aspirin), salicylic acid, salicylamide, sodium salicylate, diflunisal and niclosamide, were used for these experiments. Drugs were administered both intraperitoneally (i.p.) and orally by gavage. Out of these six salicylic acid derivatives tested, only diflunisal and niclosamide showed genotoxicity as measured by both SCE and CA assays. Acetyl salicylic acid and sodium salicylate showed weak genotoxicity as measured by SCE and CA, respectively, only at the highest dose tested.

A randomized double-blind comparative study of terbinafine for 1, 2 and 4 weeks in tinea capitis

We report a randomized, double-blind study, comparing the relative efficacy and tolerability of oral terbinafine, given for 1, 2 or 4 weeks, in tinea capitis. Of 161 evaluable patients, 53 were treated with terbinafine for 1 week, 51 for 2 weeks and 57 for 4 weeks. Isolated pathogens included Trichophyton violaceum (71.5%), T. tonsurans (14.9%), T. verrucosum (4.3%), Microsporum audouinii (4.3%), M. canis (2.5%), T. schoenleinii (1.9%) and T. mentagrophytes (0.6%). The final evaluation, at 12 weeks, showed cure rates of 73.6, 80.4 and 85.9%, in the respective groups. The adverse effects noted, were not drug related. In our opinion, terbinafine given for 1, 2 or 4 weeks, is equally effective for most cases of tinea capitis.

In vitro studies of the loss of antibacterial activity of oxytetracycline in presence of Ca(II) or Mg(II) ions

The results of a comparative study, which evaluated the in vitro effect on the antibacterial activity of oxytetracycline (OTC, CAS 79-57-2) in presence of Ca(II)/Mg(II) ions suggest that susceptibility of Staphylococcus aureus, Bacillus pumilis and Bacillus subtilis to OTC is reduced in presence of Ca(II)/Mg(II) ions. As the ratio of concentration of Ca(II)/Mg(II) to OTC was increased, antibacterial activity of OTC declined. In addition to the difference observed between the antibacterial effect of pure OTC and its Ca(II)/Mg(II) complexes, it was found that decline in antibacterial activity is greater for Mg(II)-OTC complex than Ca(II)-OTC complex for the same concentration of Ca(II)/Mg(II) ions.

Transcranial Doppler ultrasonography and transesophageal echocardiography in the investigation of pulmonary arteriovenous malformation in a patient with hereditary hemorrhagic telangiectasia presenting with stroke

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is associated with a high incidence of pulmonary arteriovenous malformations (PAVMs), which can be the underlying cause for cerebral ischemia or brain abscess. The diagnosis of these malformations may be difficult, as clinical or radiological findings may be absent. Transcranial Doppler ultrasound (TCD) with saline contrast and transesophageal echocardiography (TEE) with saline contrast are useful in identifying patients with right-to-left shunts and may help identify PAVMs.

CASE DESCRIPTION

A 68-year-old woman with HHT presented with two strokes over a 1-year period. After the first stroke, a transthoracic echocardiogram with saline contrast demonstrated significant right-to-left shunt that was interpreted as a patent foramen ovale. After the second stroke, a TCD contrast study confirmed this right-to-left shunt; however, a TEE contrast study discovered an extracardiac shunt. Pulmonary angiography revealed a left lower lobe PAVM and three telangiectasias involving the right lung. The PAVM was subsequently embolized. Postembolization radiographic imaging showed complete occlusion of the feeding vessel to the PAVM. However, repeated contrast TCD and TEE demonstrated persistent right-to-left shunting.

CONCLUSIONS

In our patient, stroke may have resulted from peripheral venous emboli passing through the PAVM or from endogenous thromboemboli originating within the PAVM. TCD and TEE contrast studies were helpful in judging the efficacy of catheter embolization therapy of PAVM. TCD and TEE with saline contrast may be clinically useful follow-up examinations for recurrence or development of new PAVMs.

Pattern of cancer in Madina Al-Munawara region

This is a retrospective study of 2237 histologically proven cases of cancer over a 12 year period from 1981 to 1993. There were 1687 (75.4%) Saudi and 550 (24.6%) non-Saudi patients. Among both sexes, the most common malignancies were from the gastrointestinal tract (29.3%), lymphoma/leukemia (18.4%), head and neck (8.8%) and breast (8.5%). The most common malignancies among males were lymphoma/leukemia, hepatoma, skin and stomach. Among females, the order of frequency of malignancy was breast, lymphoma/leukemia, esophagus, colon and thyroid. Comparison with other leading studies of the Kingdom has been made. The most common malignancies were discussed with the possible etiological factors.

Atypical case of cystic fibrosis

A patient of cystic fibrosis is hereby reported. He had no family history and presented with chest symptoms, only. There was no evidence of hepatic or pancreatic involvement. To our knowledge this represents the first case of its kind from this part of country.

In vitro studies of the antibacterial and antifungal activity of oxine and its derivatives

Twenty-one derivatives of 8-hydroxyquinoline (oxine, 8H, CAS 148-24-3) were prepared and characterized by UV, IR, MS and NMR spectroscopy. Four of these derivatives, N-butyl, 8-butyloxyquinolinium bromide (HBD), 8-pentyloxyquinoline (HPEM), N-pentyl, 8-pentyloxyquinolinium bromide (HPED) and N-benzyl, 8-benzyloxy quinolinium chloride (HBED) are new and reported for the first time. The antimicrobial activity of these compounds was carried out in vitro against 11 Gram positive and 18 Gram negative bacteria, and 18 fungi including 9 dermatophytes, 7 other filamentous fungi and 2 Candida species. Three compounds namely, HPRD, HPED and HBED were found to possess significant antibacterial activity in order of HPED > HPRD > HBED, whereas 4 were found to possess significant antifungal activity in order of 8H > HT > HPEM > 8B.

Synthesis of alkyl catechols and evaluation of their antibacterial and cyfotoxic activity

A series of potential biologically active mono-, di- and tetra- alkyl catechols were prepared through Friedel- Crafts alkylation of catechol, and evaluated for their antibacterial and cytotoxic activity. The mono-substituted alkyl derivatives showed maximum antibacterial activity in vitro which increased with the increasing length of the alkyl chains. Primary screening results indicated that all the monoalkyl derivatives except 4- (2-octyl) catechol inhibited the growth of B. bronchoseptica and maximum zones of inhibition were observed in case of monohexyl catechols (both n- and 2-hexyl) and monobenzyl derivative. In case of Gram-negative organisms growth of Kl. pneumoniae and A. calcoaceticus was inhibited by several derivatives. Mono-3-octyl-, monononyl- and monobenzyl catechols markedly inhibited the growth of Kl. pneumoniae. Mono-2-heptyl catechol inhibited the growth of six Gram-negative bacteria. Minimum inhibitory concentration of six most active compounds of the series was determined against Gram-positive and Gram-negative organisms; it ranged from < 100 mug/ml to l0 mug/ml. The antibacterial activity of catechol was not significant. Cytotoxicity test done by brine shrimp assays showed that the order of cytotoxicity decreases in going from mono- to tetra- alkyl catechols, and among the mono- alkyl products, a decrease in order of cytotoxicity was noted in going from mono-methyl catechol (LD(50) = 59) to monopentyl catechol (LD(50) = 173) after which the order of cytotoxicity gradually increased upto the largest alkyl substituent tested i.e. monononyl catechol (LD(50) = 114). Methyl and ethyl catechol, which were almost inactive in respect of their antibacterial activity possessed prononounced cytotoxicity as compared to higher homologues. Catechol itself did not show significant cytotoxicity (LD(50) = 393.27).