Quasi-Static Pull-in: an Instability in Electrostatic Actuators.

We identify a new instability in electrostatic actuators dubbed quasi-static pull-in. We report experimental evidence of the instability and study its characteristics in two types of micro actuators operating in ambient air. We found that the underlying mechanism is a fast-slow dynamic interaction between slowly-varying electrostatic excitation and fast resonator response that instigate large non-resonant oscillatory orbits and eventually disappears in a global Shilnikov bifurcation. Based on these findings, we formulate and present a new taxonomy of pull-in instabilities in electrostatic actuators.

The anti-inflammatory, analgesic and antipyretic activity of Nigella sativa.

The aqueous extract of Nigella sativa (N. sativa) was investigated for anti-inflammatory, analgesic and antipyretic activities in animal models. The extract has an anti-inflammatory effect demonstrated by its inhibitory effects on Carrageenan induced paw edema. It also produced significant increase in the hot plate reaction time in mice indicating analgesic effect. However, N. sativa crude suspension had no effect on yeast induced pyrexia. This study therefore, supports its use in folk medicine both as analgesic and anti-inflammatory agent and calls for further investigations to elucidate its mechanism of action.

Evidence of a functional role in lung inflation for the buccal pump in the agamid lizard, Uromastyx aegyptius microlepis.

This study has demonstrated that the agamid desert lizard Uromastyx aegyptius microlepis ventilates its lungs both with a triphasic, thoracic aspiratory pump and by gulping air, using a buccal pump. These two mechanisms never occur simultaneously because bouts of buccal pumping are always initiated after the passive expiration that terminates a thoracic breath. Lung inflation arising from thoracic and buccal ventilation was confirmed by direct recording of volume changes using a whole-body plethysmograph. This observation was further confirmed by mechanical separation of the inflationary pressures associated with these two breathing mechanisms, enabling the effects of lung inflation on buccal breathing to be observed. This revealed that the buccal pump is influenced by a powerful Hering-Breuer-type reflex, further confirming its role in lung inflation. Bilateral thoracic vagotomy tended to increase the variance of the amplitude and duration of the breaths associated with the aspiration pump and abolished the effects of lung inflation on the buccal pump. Uromastyx has vagal afferents from pulmonary receptors that respond to changes in lung volume and appear not to be sensitive to CO2. This study describes two lung-inflation mechanisms (an amphibian-like buccal pump and a mammalian-like aspiration pump) in a single extant amniote, both of which are subject to vagal feedback control.

Empirical treatment of uncomplicated urinary tract infection by community pharmacist in the Eastern province of Saudi Arabia.

OBJECTIVE: It is a well known phenomenon in the Kingdom of Saudi Arabia that prescription drugs are dispensed over the counter in the community pharmacies. The aim of this study is to document the attitude of community pharmacists to fulfill the concept of pharmaceutical care and to evaluate how they manage a case of acute uncomplicated lower urinary tract infection. METHODS: Eighty-eight community pharmacists in the Eastern province of Saudi Arabia were presented with a patient claiming urinary tract infection and seeking medical treatment. RESULTS: Only one attendant pharmacist refused to dispense medications without prescription. Fifteen others (17%) dispensed urinary antiseptic only and 72 (82%) gave antibacterial agents. Fluoroquinolones were the most commonly dispensed (69%) as first choice and 87% as an alternative) followed by co-trimoxazole, penicillins, cephalosporins and tetracyclines. The number of drugs dispensed ranged from a single agent at 52 (59%), 2 drugs at 31 (35%) and 3 drugs at 4 (4.5%) pharmacies. The average cost was Saudi Riyal (SR) 45.8 ($12.2) for first choice drugs and SR 31.5 ($ 8.4) for the alternatives. CONCLUSION: The heavy dispensing of fluoroquinolones over the counter could eventually lead to increased resistance of the pathogenic bacteria to these drugs. However, despite the lack of pharmacist's adherence to the pharmaceutical law, this study does not indicate that they had abused their patients. It is rather demonstrating the urgent needs for successful implementation of the pharmaceutical law taking into consideration better integration between governmental health providers and the private retail pharmacies. In addition, it supports calls to educate pharmacists to perform basic clinical assessment in the community pharmacy, as a vital tool to effectively manage their patients' health status. The Ministry of health should credit such educational activity for the renewal of pharmacist's license in the Kingdom.

Continuing pharmaceutical education for community pharmacists in the eastern province of saudi arabia.

BACKGROUND: Community pharmacists in Saudi Arabia very often make decisions that affect patient outcome. Previous studies have indicated that they have access to limited sources of information. Therefore, structured continuing pharmaceutical education (CPE) is necessary to improve their standards and attitudes. AIMS: Identify the most important topics for CPE as well as the most significant barriers to conducting CPE successfully. METHODS: A questionnaire was distributed to 120 pharmacists working in 88 community pharmacies in the Eastern Province of Saudi Arabia. The survey contained five sections: general background, topics for CPE that could be of great interest to community pharmacists, possible obstacles to attending CPE, method of instruction, and the most suitable time and day of the week for conducting CPE. RESULTS: One hundred and five (87.5%) pharmacists answered the survey questionnaire. The rank order of the five most selected topics for CPE were: drug interaction (81.9%), drug use during pregnancy (77.1%), use of anti-microbial agents (62.5%), pharmaceutical ethics (53.3%), geriatric and pediatric pharmacology (45.7%). For pharmacists, the most important obstacles to attending CPE were lack of time (96.2%), distance from practice (74.2%), and lack of programs or information about these programs (54.3%). Interestingly, 47.6% of the pharmacists recommended credentialing CPE and stated that knowing the lecturer was not considered an important factor. CONCLUSION AND RECOMMENDATIONS: The findings of this study demonstrated that pharmacists are willing to participate in CPE programs. However, the working conditions of pharmacists would be a major barrier to their attendance. Therefore, improvement of the working conditions of community pharmacists, development of credited CPE programs in each region, as well as improving communication between the Saudi Pharmaceutical Association and community pharmacists are highly recommended.

Residues of tetracycline compounds in poultry products in the eastern province of Saudi Arabia.

Chicken muscle, liver and egg samples were collected from 33 broiler and 5 layer farms in the eastern province of Saudi Arabia over a period of two years starting from January 1996. Antibiotic-residue positive samples were identified in the products of 23 (69.7%) broiler and 3 (60%) layer poultry farms. 87% and 100.0% of the antibiotic-residue positive broiler farms were positive for at least one tetracycline compound in raw muscle and liver respectively, while 73.9% and 95.5% were positive for 2 or more tetracyclines in these two tissues, respectively. Furthermore, 82.6% and 95.5% of the antibiotic-residue-positive farms had mean concentrations of at least one tetracycline compound in excess of the permissible maximum residue limit (MRL) in raw muscle and liver, respectively. These compounds also remained chemically detectable after cooking. Tetracycline levels exceeded MRL in 14.4% of antibiotic-positive raw eggs but the overall mean tetracycline concentration in each farm was below MRL. This study confirmed widespread misuse of tetracycline agents including multiple use of drugs belonging to the same pharmacological group and lack of implementation of recommended withdrawal times. This may be contributing to the high resistance rates to tetracyclines in both chicken and human microbial isolates observed in the region. This study, therefore, stresses the need for stricter regulations for the use of antimicrobial drugs in the poultry industry as well as the inspection of chicken for drug residues prior to marketing.

Use of norfloxacin in poultry production in the eastern province of Saudi Arabia and its possible impact on public health.

Samples of market-ready chicken muscle and liver from 32 local broiler farms were first screened for antibiotic residues by microbiological assay. The antibiotic-residue-positive muscles and livers from 22 farms were further analysed for norfloxacin (NFX) residues by high performance liquid chromatography. NFX was detected in 35.0% and 56.7% of raw antibiotic-residue-positive muscles and livers, respectively. The NFX-positive muscles and livers were respectively obtained from 11 (50.0%) and 14 (63.6%) of the 22 antibiotic-residue-positive farms. Since the maximum residue limit (MRL) for NFX has not yet been fixed, the MRL for enrofloxacin was used in the study. All NFX-positive farms had mean raw tissue levels, which were 2.7- to 34.3-fold higher than the MRL. Although cooking markedly reduced NFX tissue concentrations, mean detectable levels remained above MRL in large proportions of NFX-positive samples and farms. Susceptibility patterns of Enterobacteriaceae isolates from chicken and human patients to NFX showed alarmingly high rates of resistance in chicken isolates especially among Escherichia coli (45.9%) and Pseudomonas spp. (70.6%) compared with patients' isolates (10.5% and 18.2%, respectively). The study reveals widespread misuse of NFX in the local poultry industry, which may pose a major risk to public health including possible stimulation of bacterial resistance and hypersensitivity reactions to fluoroquinolones. More prudent use of fluoroquinolones in food-producing animals is therefore recommended. Further, there is a need to establish MRL values for NFX.

Antibiotic resistance of Escherichia coli isolated from poultry workers, patients and chicken in the eastern province of Saudi Arabia.

The prevalence of antibiotic-resistant Escherichia coli isolates from faecal samples from 117 poultry industry workers, 100 patients and119 healthy chicken were compared. Resistance of E. coli chicken isolates to ampicillin, chloramphenicol, gentamicin, spectinomycin, tetracycline and trimethoprim + sulphamethoxazole (TMP + SMX) (range 57% - 99.1%) were significantly higher than those isolated from patients (range 21.9% - 71.4%) and workers (range 35% - 71.8%). However, for drugs not used in poultry, such as amoxicillin + cluvalanate (AMX + CLV), ceftazidime and nitrofurantoin, resistance rates of chicken isolates (range 0% - 2.6%) were significantly lower than those of patient isolates (range 8.7% - 30%). Resistance to spectinomycin reached 96% in E. coli chicken isolates and 71% in organisms isolated from humans. Use of this drug in Saudi Arabia is mostly limited to veterinary purposes. Multidrug resistance is alarmingly high in all groups but was highest in chicken isolates (77.4%). Serotyping of E. coli isolates showed that 27% of the organisms isolated from patients were overlapping with 10.9% of the chicken isolates, indicating the possibility of chicken being a source of the resistance pool for humans. We therefore call for the banning of antibiotics in the poultry industry as growth promoters and recommend that their use be restricted to treating infections.

Patterns of resistance to antibiotics at king fahd hospital of the university.

INTRODUCTION AND AIM: A sharp worldwide rise in bacterial resistance to antimicrobial agents in both nosocomial and community acquired pathogens has recently been observed. This may complicate treatment of infectious disease or increase the cost of its management. It is, therefore, important to regularly investigate the patterns of resistance to antimicrobial agents at both local and national levels. METHODS: The antibiograms of organisms isolated over a one-year period in King Fahd Hospital of the University were analyzed. RESULTS: Of the 3679 microbial isolates of 35 types of organisms identified, the most common were Streptococcous spp (25.5%), S. aureus (16.1%), E. Coli (12.7%), Psueudomonas spp (9.3%) and Klebsiella spp (7%) High resistance rates (>50%) to ampicillin and to amoxycillin + clavulanate (AMX+CLV) were encountered in Enterobacter spp., and H. influenzae while in E. coli, the resistance was higher to ampicillin (60.0%) than to AMX+CLV (38.1%). With regard to S. aureus, 98.3%, 91.1% and 25.5% of isolates were resistant to penicillin, AMX+CLV and methicillin respectively but all were sensitive to vancomycin. High resistance (53% of 2830 isolates) to tetracycline was also observed especially in H. influenzae (80.5%), Streptococcous spp (72.9%) and E. Coli (54.5%). The same organisms were also highly resistant to trimethoprim/sulphamethoxazole with rates of 75.5%, 80.4% and 48.1% respectively. Moderate resistance (26% of 1567 isolates) to gentamicin was noted but the drug remained very effective against most tested gram-negative organisms. In addition, multiple resistance to gentamicin and AMX+CLV was also detected in 24.3% of 839 isolates. CONCLUSIONS AND RECOMMENDATIONS: It is concluded that the alarmingly high pattern of bacterial resistance to antibiotics may reflect the extent of use of each antibiotic in the eastern province of Saudi Arabia. It is recommended that hospital antibiotic policies (purchasing, prescribing and dispensing) be based on, and regularly reviewed in accordance with hospital antibiogram results. A center for infectious disease control should also be established in each region of the Kingdom to disseminate information and coordinate antibiotic policies among hospitals.

Utilization of digoxin and theophylline assays in the eastern province.

The utilization of therapeutic drug monitoring (TDM) for serum digoxin and theophylline was assessed with respect to the indication, time of sample collection and contribution to patient care. A total of 585 serum drug level determinations of digoxin (275) and theophylline (328) were done in a four month period. Reasons for requests were subtherapeutic response (27.5%), suspected toxicity (3.8%), baseline data (26.7%), patients at risk for toxicity (7.7%), and for the remaining 34.4% of orders, no reason was stated. The highest number of requests 246 (42.1%) were from the inpatient ward (INP), followed by emergency room (ER) 32.6%, outpatient department (OPD) 13% and intensive care unit (ICU) 12.3%. Repeated assays accounted for 363 determinations of which 55.9% had levels similar to the previous ones. In this study, we found a high incidence of inappropriateness in patient selection (34.4%), time of serum sample collection (28.4%), and dosage adjustment (46.8%). However, when these audit criteria were analyzed together, the overall appropriateness was as low as 33.5%. This indicated that serum drug monitoring was poorly utilized and did not contribute much to the patient's care. This results in an estimated financial loss per year (for inappropriate use of digoxin and theophylline levels) of about 37,344 Saudi Riyals (US $9,956.00). Corrective educational programs for the staff, based on standard guidelines for TDM, have been initiated and this study is a baseline for future prospective audits.

The effect of haemodialysis on the pharmacokinetics of tenoxicam in patients with end-stage renal disease.

We have studied the pharmacokinetics of tenoxicam after single and multiple oral doses of 20 mg in five patients (2 men and 3 women) with end-stage renal disease undergoing haemodialysis. After a single dose, tenoxicam had a half-life (t1/2) of 33 h, an apparent clearance (CL.f-1) of 4.3 ml.min-1, and an apparent volume of distribution (Vz.f-1) of 11.81. The maximum tenoxicam concentration (Cmax) was 4.3 mg.l-1 at a median tmax of 1.7 h. There were no significant differences between the values calculated from the pre- or post-dialyser port plasma samples. Tenoxicam plasma concentrations measured during once daily dosing before and after haemodialysis showed that tenoxicam does not accumulate. Our findings suggest that dosage adjustment may not be required in patients with end-stage renal disease on haemodialysis taking tenoxicam.

Antiemetic efficacy of cimetidine randomized, double-blind, crossover study with dexamethasone in cancer patients receiving emetogenic chemotherapy.

In a randomized, double-blind, crossover study the antiemetic effect of cimetidine was compared with that of dexamethasone in cancer patients receiving emetogenic chemotherapy. Thirty-two patients were evaluable and all were chemotherapy-naive. Eight patients (25%) received high doses of cisplatin, 17 (53%) had cyclophosphamide in combination treatment, 2 (6%) received adriamycin, and 1 another chemotherapy of less emetogenic potential. Complete protection (CR) rates of 59.4% and 62.5% were achieved with cimetidine and dexamethasone, respectively. In addition, three (9.4%) and 1 (3%) patients attained partial protection with cimetidine and dexamethasone, respectively. No significant difference was noted between the two antiemetic therapies (p = 0.07). Although CR has not been achieved in any of those patients who received cisplatin, a comparable antiemetic effect was attained. Both antiemetic regimens were well tolerated with minimal side effects. We conclude that the antiemetic potential of cimetidine and its safety deserve further investigation in a larger study, perhaps in combination with other antiemetic agents.

Tenoxicam-induced gastropathy in the rat: a comparison with piroxicam and diclofenac sodium, and the inhibitory effects of ranitidine and sucralfate.

The ulcer-inducing potential, indicated by the oral dose that induced gastric ulcers in 50% of rats, was higher for tenoxicam (10.2 mg/kg) than for diclofenac sodium (34 mg/kg, equivalent to 6.8 mg/kg tenoxicam) or piroxicam (6.2 mg/kg). The mean lesion scores, a measure of the intensity of ulceration, using 16 and 32 mg/kg tenoxicam given orally were 3.6 +/- 3.4 and 8.7 +/- 7.3, respectively, compared with 9.6 +/- 6.4 and 24.7 +/- 10.5, respectively, for similar oral doses of piroxicam; the differences were statistically significant (P less than 0.05 and P less than 0.001, respectively). The mean lesion score for 32 mg/kg tenoxicam was also significantly (P less than 0.05) less than that for 160 mg/kg diclofenac sodium: 8.7 +/- 7.3 compared with 14.8 +/- 8.1. Ranitidine (20 40 mg/kg) and 260-520 mg/kg sucralfate but not 4 mg/kg ranitidine strongly inhibited ulceration induced by 32 mg/kg tenoxicam.