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Biomedical subjects

S Vaidyanathan

Publications and source records attributed to S Vaidyanathan.

At least 19 recordsLinked to original sources
PubMed2006

Chronic lymphocytic leukaemia, synchronous small cell carcinoma and squamous neoplasia of the urinary bladder in a paraplegic man following long-term phenoxybenzamine therapy.

STUDY DESIGN: A case report. OBJECTIVE: To raise awareness among spinal cord clinicians of the possible carcinogenic effect of phenoxybenzamine and of the rare occurrence of small cell carcinoma in the neuropathic bladder. SETTING: Regional Spinal Injuries Centre and District General Hospital, Southport, Merseyside, United Kingdom. CASE REPORT: A 28-year-old man sustained a fracture dislocation of L-1 with consequent paraplegia (ASIA impairment scale A). Phenoxybenzamine treatment enabled his indwelling catheter to be discarded in favour of a penile sheath, but it caused unacceptable dizziness and was stopped after 7 years. After 20 years, he developed chronic lymphocytic leukaemia, which was treated with chlorambucil and fludarabine. After 2 years, investigation of bilateral hydronephrosis revealed a primary small cell carcinoma of the bladder with coexistent squamous dysplasia. Uraemia supervened and, declining active treatment, the patient died 3 weeks after diagnosis. CONCLUSION: Phenoxybenzamine, a known carcinogen in rodents, is likely also to be carcinogenic in humans, and patients with spinal cord injury who have received the drug for any significant period of time, need close follow-up to allow early detection of cancer. Phenoxybenzamine should not be prescribed on a long-term basis, and should instead be replaced with a selective alpha-blocker.

Adult↗
PubMed2006

Telementoring in endocrine surgery: preliminary Indian experience.

Telemedicine is starting to play an important role in the health field in India. In this case report we describe the successful use of telementoring to remove a parathyroid tumor in a patient with residual hyperparathyroidism after two previous unsuccessful attempts in tumor excision. A 21-yr-old patient crippled with advanced hyperparathyroidism was taken up for third-time exploration at Amrita Institute of Medical Sciences (AIMS), Kochi, with guidance from the Sanjay Gandhi Postgraduate Institute of Medical Sciences (SGPGIMS), Lucknow, using telemedicine technology. These two centers are located 2,500 km apart, and telementoring from the more experienced endocrine surgeons at SGPGIMS resulted in successful tumor localization and removal. For this session both the institutions were provided with a dedicated 512 Kbps very small aperture terminal (VSAT) link and two-way video-audio connectivity. Even though two previous explorations were unsuccessful, with the help of telemedicine technology the same surgeon was successful in locating and removing the tumor. The video and audio quality was of good enough quality for the expert at SGPGIMS to guide the team at AIMS satisfactorily. The patient benefited since he did not have to travel to a far-off specialized center for surgery. This case report testifies to the usefulness of telemedicine in the field of surgery, especially in developing countries, which have few medical experts in certain specialized areas.

Adult↗
PubMed2006

Lack of pharmacokinetic interactions of aliskiren, a novel direct renin inhibitor for the treatment of hypertension, with the antihypertensives amlodipine, valsartan, hydrochlorothiazide (HCTZ) and ramipril in healthy volunteers.

Aliskiren is a novel, orally active direct renin inhibitor that lowers blood pressure alone and in combination with existing antihypertensive agents. As aliskiren does not affect cytochrome P450 enzyme activities, is minimally metabolised, and is not extensively protein bound, the potential for drug interactions is predicted to be low. Four open-label studies investigated the pharmacokinetic interactions between aliskiren 300 mg and the antihypertensive drugs amlodipine 10 mg (n = 18), valsartan 320 mg (n = 18), hydrochlorothiazide 25 mg (HCTZ, n = 22) and ramipril 10 mg (n = 17) in healthy subjects. In each study, subjects received multiple once-daily doses of aliskiren and the test antihypertensive drug alone or in combination in two dosing periods separated by a drug-free washout period. Plasma concentrations of drugs were determined by liquid chromatography and mass spectrometry methods. At steady state, relatively small changes in exposure to aliskiren were observed when aliskiren was co-administered with amlodipine (AUC(tau) increased by 29%, p = 0.032), ramipril (C(max,ss) increased by 31%, p = 0.043), valsartan (AUC(tau) decreased by 26%, p = 0.002) and HCTZ (C(max,ss) decreased by 22%, p = 0.039). Co-administration with aliskiren resulted in small changes in exposure to ramipril (AUC(tau) increased by 22%, p = 0.002), valsartan (AUC(tau) decreased by 14%, p = 0.062) and HCTZ (AUC(tau) decreased by 10% and C(max,ss) by 26%, both p < 0.001). All other changes in pharmacokinetic parameters were also small, and not statistically significant. None of the observed pharmacokinetic changes was considered clinically relevant. Aliskiren inhibited plasma renin activity (PRA) and also prevented the reactive rise in PRA induced by valsartan. The most commonly reported adverse events were headache, dizziness and gastrointestinal symptoms (all mild in severity), which were similar in frequency during antihypertensive drug treatment alone and in combination with aliskiren except for an increase in dizziness during treatment with the combination of aliskiren and HCTZ. In conclusion, aliskiren shows no clinically relevant pharmacokinetic interactions and is generally well tolerated when administered in combination with amlodipine, valsartan, HCTZ or ramipril.

Adolescent↗
PubMed2006

Evaluation of the pharmacokinetic interaction between fluvastatin XL and cyclosporine in renal transplant recipients.

OBJECTIVE: To assess the pharmacokinetic interaction between cyclosporine and extended-release fluvastatin (fluvastatin XL), 80 mg for 7 days, in stable renal transplant recipients. METHODS: This was a single-center, open-label study. 17 renal transplant recipients received their standard cyclosporine therapy (Days 1 - 9) plus a once-daily single oral dose of fluvastatin XL, 80 mg (Days 2 - 8). Blood samples were collected and cyclosporine (whole blood) and fluvastatin (plasma) concentrations determined by radioimmunoassay and HPLC fluorescence detection, respectively. Pharmacokinetic parameters were calculated using non-compartment analysis and fluvastatin results were compared with historical controls. RESULTS: Treatment with fluvastatin XL, 80 mg for 7 days, had no significant effect on either the AUC0-12 (3,644 ng x h/ml in the absence of fluvastatin vs. 3,534 ng x h/ml in the presence of fluvastatin) or the Cmax of cyclosporine (983 ng/ml in the absence of fluvastatin vs. 945 ng/ml in the presence of fluvastatin). Co-administration of fluvastatin XL also had no effect on the tmax, t1/2 or apparent clearance (CL/F) of cyclosporine in renal transplant patients. The AUC and Cmax for fluvastatin XL in the presence of cyclosporine (AUC0-24 1,192 ng. x h/ml, Cmax 271 ng/ml) were approximately 2-fold higher compared with historical data for fluvastatin XL alone in healthy volunteers (AUC0-24 630 ng x h/ml, Cmax 102 ng/ml) but lower than the historical data for fluvastatin IR, 40 mg b.i.d. alone in healthy volunteers (AUC0-24 1,340 ng x h/ml, Cmax 443 ng/ml). Tmax, t1/2 and trough levels of fluvastatin in the presence of cyclosporine were also similar to the historical controls. Concomitant administration of cyclosporine and fluvastatin XL was well tolerated by renal transplant recipients. CONCLUSIONS: Fluvastatin XL, 80 mg, and cyclosporine do not show clinically relevant pharmacokinetic interactions.

Administration, Oral↗
PubMed2005

Two case reports of cervical spinal cord injury in football (soccer) players.

STUDY DESIGN: Two case reports of male football players who sustained injury to cervical spinal cord as a direct result of the sport. OBJECTIVE: To raise the awareness that playing football (soccer), a very popular sport, may cause injury to the cervical spinal cord with dire consequences, albeit rarely. SETTING: North West Regional Spinal Injuries Centre, Southport, UK. CASE REPORT: We report two male football players, who sustained injury to the cervical spine and developed tetraplegia as a direct result of the sport. Case 1: A 21-year-old football player was tackled from behind while running with the football, he lost his balance and landed on his head resulting in burst fracture dislocation of C5/C6 associated with immediate onset of complete tetraplegia (ASIA-A). Case 2: A 24-year-old football player collided, head first, with his own team goalkeeper, causing a hyperextension of neck. He developed motor complete tetraplegia at C5 level, with some sensation sparing below the level of injury (ASIA-B). CONCLUSION: Injury to the cervical spinal cord is known to occur in some team contact sports such as rugby and American football. Over time the laws and the preparation of the athletes for these games have been changed in order to minimize the neck injuries. What might not be appreciated is that playing football (soccer), a very popular sport worldwide, may cause injury to cervical spinal cord with dire consequences.

Adult↗
PubMed2005

Location of urethral arteries by colour Doppler ultrasound.

STUDY DESIGN: A case report. SETTING: Regional Spinal Injuries Centre, Southport, UK. CASE REPORT: A 56-year-old male with complete paraplegia at T-4 underwent visual internal urethrotomy of bulbous urethral stricture with a cold knife at 12 o'clock position. There was brisk arterial bleeding. Despite receiving antibiotics, this patient developed hypotension, tachycardia and tachypnoea. He was resuscitated and mechanical ventilation was instituted. After he recovered from this life-threatening episode of urinary tract-related sepsis, colour Doppler ultrasound imaging of bulbous urethra was performed to locate urethral arteries. In the bulbous urethra, single urethral artery was seen at 12 o'clock position. CONCLUSION: Since the sites of urethral arteries vary among patients, it is advisable to assess individually the location of urethral arteries preoperatively and plan the site of incision accordingly. Persons with injury to cervical or upper dorsal spinal cord have decreased cardiac and respiratory reserve as well as alteration in immune function. Therefore, all possible measures should be taken to prevent acute blood loss and bacteraemia in this group of patients.

Arteries↗
PubMed2005

Recurrent vesical calculi, hypercalciuria, and biochemical evidence of increased bone resorption in an adult male with paraplegia due to spinal cord injury: is there a role for intermittent oral disodium etidronate therapy for prevention of calcium phosphate bladder stones?

STUDY DESIGN: Clinical case report with comments by colleagues from Sweden, Poland, Spain, Brazil, Japan, Belgium and Switzerland. OBJECTIVES: To discuss the role of disodium etidronate therapy for prevention of calcium phosphate vesical calculi in persons with spinal cord injury, who have hypercalciuria and biochemical evidence of increased bone resorption. SETTING: Regional Spinal Injuries Centre, Southport, UK. METHODS: A 21-year-old male sustained paraplegia (T-10; ASIA scale: A) in a road traffic accident in June 2001. He had an indwelling urethral catheter until the end of August 2001, when he started self-catheterisation. He developed bladder stones and electrohydraulic lithotripsy (EHL) was performed in May 2002. All stone fragments were removed. Recurrence of vesical calculi was noted in October 2002. These stones were fragmented by lithoclast lithotripsy in two sessions, in December 2002 and February 2003; all stone fragments were removed at the end of the second session. This patient reverted to indwelling catheter drainage when vesical calculi recurred. In September 2003, X-ray of the abdomen showed recurrence of vesical calculi. By February 2004, the stones had increased in size and number. EHL of vesical calculi was again performed in April 2004. Complete clearance was achieved. RESULTS: A 24-h urinalysis detected hypercalciuria--18.7 mmol/day (reference range: 2.5-7.5). Biochemical analysis of vesical calculus revealed calcium phosphate (85%) and magnesium ammonium phosphate (15%). Plasma C-terminal telopeptide (CTX) was increased - 1.06 ng/ml (reference range: 0.1-0.5 ng/ml). Free deoxypyridinoline/creatinine ratio (fDPD/Cr) in urine was also increased - 20.2 (reference range: 2.3-5.4). In April 2004, this patient was prescribed disodium etidronate 400 mg day. Nearly 3 months after commencing therapy with etidronate, plasma CTX decreased to 0.87 ng/ml. fDPD/Cr in urine also decreased to 12.4. After 4 months of etidronate therapy, 24-h urinary calcium excretion had decreased to 6.1 mmol/day. CONCLUSION: Etidronate (400 mg daily) is a very effective inhibitor of calcium phosphate crystallisation. Etidronate decreased urinary excretion of calcium, an important factor in prevention of calcium phosphate bladder stones. Etidronate therapy is not a substitute for other well-established methods for prevention of vesical calculi in spinal cord injury patients, for example, large fluid intake, avoiding long-term catheter drainage. Intermittent therapy with etidronate may be considered in selected patients, in whom hypercalciuria persists after instituting nonpharmacological therapy for an adequate period, for example, early mobilisation, weight-bearing exercises, and functional electrical stimulation. However, possible side effects of etidronate, and the fact that etidronate is not licensed in United Kingdom for prevention of urolithiasis, should be borne in mind.

Adult↗
PubMed2005

Pharmacokinetic interactions of the oral renin inhibitor aliskiren with lovastatin, atenolol, celecoxib and cimetidine.

OBJECTIVE: Aliskiren is the first in a new class of orally effective renin inhibitors for the treatment of hypertension. This study investigated the interaction profile of aliskiren, which is of clinical importance because hypertensive patients often require concomitant drug therapy for associated comorbidities. METHODS: Four separate studies investigated the pharmacokinetic interaction between single oral doses of aliskiren and lovastatin, atenolol, celecoxib or cimetidine, respectively. All studies involved healthy male volunteers aged 18-45 years. In 3 studies, subjects (n = 15 in each study) received single doses of aliskiren 150 mg alone, the test drug alone (lovastatin 40 mg, atenolol 100 mg or celecoxib 200 mg), or both drugs in combination, according to a 3-period crossover design. In the cimetidine study (n = 12), aliskiren 150 mg was administered alone or concomitantly with cimetidine 800 mg according to a two-period crossover design. Plasma concentrations of aliskiren and test drugs were determined by liquid chromatography and mass spectrometry methods. Pharmacokinetic parameters were derived from these data. RESULTS: Mean AUC and t1/2 for aliskiren were not significantly changed by lovastatin, atenolol or celecoxib (< 10% difference between treatments). Aliskiren mean Cmax was not affected by either lovastatin or atenolol, although a non-significant 36% increase was observed with celecoxib. Modest, non-significant increases in aliskiren systemic availability followed coadministration with cimetidine (aliskiren mean AUC, Cmax and t1/2 increased by 17%, 19% and 15%, respectively). Aliskiren coadministration had no significant effect on the disposition of lovastatin, atenolol or celecoxib. CONCLUSIONS: Overall, single doses of aliskiren showed no evidence of clinically important pharmacokinetic interactions with lovastatin, atenolol, celecoxib or cimetidine.

Adolescent↗
PubMed2005

Pseudomonas sepsis with Noma: an association?

We report here a 2.5-year-old male child with community-acquired Pseudomonal sepsis showing the characteristic lesions of ecthyma gangrenosum. The child had development of gangrenous changes of the nose and face - the 'cancrum oris' or 'Noma'. We highlight the possible association of Pseudomonas sepsis and Noma, with malnutrition playing a central role in causing both the diseases.

Child Nutrition Disorders↗
PubMed2004

Calculus anuria in a spina bifida patient, who had solitary functioning kidney and recurrent renal calculi.

STUDY DESIGN: Clinical case report with comments by colleagues from Austria, Belgium, Germany, Japan, and Poland. OBJECTIVES: To discuss challenges in the management of spinal bifida patients, who have marked kyphoscoliosis and no vascular access. SETTING: Regional Spinal Injuries Centre, Southport, UK. METHODS: A female patient, who was born with spina bifida, paraplegia and solitary right kidney, had undergone ileal loop urinary diversion. Renal calculi were noted in 1986. Percutaneous nephrostolithotomy was performed in 1989 and there was no residual stone fragment. However, she developed recurrence of calculi in the lower pole of the right kidney in 1991. Intravenous urography, performed in 1995, revealed right staghorn calculus and hydronephrosis. Chest X-ray showed markedly restricted lung volume due to severe kyphoscoliosis. In 2000, she was declared unsuitable for anaesthesia due to a lack of venous access and a high likelihood of difficulty in weaning off the ventilator in the postoperative period. In June 2002, she developed anuria (urine output=18 ml/24 h) due to ball-valve-type obstruction by a renal stone at the ureteropelvic junction. Urea: 14.4 mmol/l; creatinine: 236 microl/l. Ultrasound showed right hydronephrosis. Percutaneous nephrostomy was performed. RESULTS: Following relief of urinary tract obstruction, there was postobstructive diuresis (3765 ml/24 h). However, the patient expired 19 days later due to progressive respiratory failure. CONCLUSION: In this spina bifida patient, who had reached the age of 35 years, severe kyphoscoliosis and lack of vascular access presented insurmountable challenges to implement the desired surgical procedure for removal of stones from a solitary kidney.

Adult↗