Biomedical subjects
K Wilkinson
Publications and source records attributed to K Wilkinson.
Pharmacokinetic modeling of the lung burden from repeated inhalation of nickel aerosols.
The saturable nature of the clearance of soluble nickel compounds from the lung was studied by repeated exposures of rats to respirable submicron-size nickel aerosols. Using Michaelis-Menten type kinetics for removal of nickel lung burdens and a constant rate of deposition, the lung nickel burdens were simulated by computer. The computer simulation was used to design a repeated exposure regimen to test further the hypothesis of saturable clearance. Male Sprague-Dawley rats were exposed for 2 h/day to nickel chloride aerosols at either 90 or 400 micrograms Ni/m3 for up to 14 days. During the 22 h between exposures and up to 3 days post-exposure rats were kept in clean air. The particle size of the aerosol ranged from 0.7 to 0.9 micron mass median aerodynamic diameter with a geometric standard deviation of 1.2-1.4. A steady-state nickel lung burden was observed at 90 micrograms/m3, as predicted from computer modeling, while lung burdens continued to increase with repeated exposure to 400 micrograms Ni/m3. The best fit for the experimental data was obtained with a maximum clearance velocity (Vmax) of 34.6 ng Ni/g X h and a Michaelis-Menten constant for transport (Kt) of 1380 ng Ni/g. The percentage of submicron nickel chloride aerosols retained in the lung was 6.9%. These data support the hypothesis of a saturable clearance mechanism for soluble nickel and provide physiological constants useful for estimating human health risks from nickel inhalation.
Tactile orotracheal tube placement test. A bimanual tactile examination of the positioned orotracheal tube to confirm laryngeal placement.
The development of a tactile clinical test of the positioned orotracheal tube is described which allows confirmation of its location within the larynx. It was possible, after preliminary experience with the test, to confirm laryngeal placement confidently in an average of 97% of cases in two concurrent series each of which consisted of 100 patients. Inevitably, there are limitations to its usefulness but it has the advantage that no special apparatus is required for its performance. The implications of this test are discussed in relation to difficult intubation, obstetric anaesthesia, the teaching of applied anatomy and checking by their trainers of intubations performed by very junior anaesthetists. Familiarity with this test should be considered essential for its reliable implementation.
Pacemaker assessment for junior doctors.
Recent experience at the Merseyside Regional Pacemaker Centre has emphasized that many junior doctors are unfamiliar with numerous important facts regarding permanent pacemakers. It is important to detect quickly a fault in a permanent pacemaker if, for example, a patient presents with recurrent dizziness, blackouts or a cerebrovascular accident.
Comparison of vitreous carbon and elgiloy transvenous ventricular pacing leads.
In a randomized prospective study of 150 patients, we compared two porous-tipped, finned leads, one with a vitreous carbon tip (surface area = 12 mm2) and the other with an Elgiloy tip (surface area = 8 mm2). We assessed the acute and chronic stimulation thresholds and the ease of implantation of the two leads. The acute current thresholds for the vitreous carbon and Elgiloy-tipped leads were 1.7 +/- 0.5 (+/- SD) mA vs. 1.1 +/- 0.4 mA (0.25 ms pulse width), 1.3 +/- 0.5 mA vs. 0.9 +/- 0.3 mA (0.5 ms), and 1.0 +/- 0.3 mA vs. 0.8 +/- 0.3 mA (0.75 ms), respectively (P less than 0.0005). Impedance at implantation was 473 +/- 121 ohms and 716 +/- 285 ohms (P less than 0.0005) for the carbon-tipped and Elgiloy-tipped leads, respectively. The R-wave amplitudes were 10.2 +/- 5.1 volts and 6.8 +/- 3.0 volts, respectively (P less than 0.0005). Both leads were easy to implant and showed low stable chronic thresholds from 3 weeks after implantation, at which time the stimulation threshold was 1.9 +/- 1.0 volts vs. 1.5 +/- 0.6 volts with the implanted voltage-variable generators and 1.8 +/- 0.8 mA vs. 1.6 +/- 0.6 mA with the implanted current-variable generators. Reoperation for displacement was required for two of the 87 (2.3%) carbon-tipped and 2 of the 67 (3.2%) Elgiloy-tipped leads. There was no exit block nor any other lead-related complication. We conclude that both leads have similar and satisfactory performance.
Experience with 407 transvenous, finned pacing leads with a sintered porous-surfaced electrode.
Experience with 407 transvenous ventricular finned pacing leads with a sintered porous-surfaced electrode is reported. A low complication rate was encountered: 97% of patients were free from lead-related complications. Four patients (1%) required re-operation: two for lead displacement, one for failure to sense spontaneous ventricular activity and one for exit block. A further patient developed exit block which resolved spontaneously. The vast majority of patients had low chronic stimulation thresholds; for example at six months after implantation, the mean threshold for a group of pacemakers with a pulse duration of 0.5 ms was 1.4 +/- 0.7 V and for another group with a pulse duration of 0.8 ms it was 1.9 +/- 0.7 mA. However, six patients developed a transient high stimulation threshold during the month after implantation, and a high threshold developed in another patient at five months and persisted. Mean acute stimulation and sensing thresholds were satisfactory: 0.7 +/- 0.2 V at 0.5 ms pulse duration and 7.6 +/- 2.4 mV, respectively.
Rapid assay of fibrinogen chromatograms in syndromes of intravascular coagulation.
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Lysozymuria in diabetes.
A reversible lysozymuria indicative of proximal tubular damage to the kidney was found in three out of five patients with diabetic ketosis, and a persistent lysozymuria was found in many patients with diabetic nephropathy. There was no relation between lysozymuria and the degree of proteinuria, and lysozymuria was not due to urinary tract infection. The degree of lysozymuria could be used to assess the severity of diabetic nephropathy.
Free phenols in chronic renal failure.
Serum total free phenols are elevated in chronic renal failure, acute renal failure and hepatic coma. Being partly protein-bound, phenols behave during dialysis in a similar manner to considerably larger molecules which are not protein-bound. In view of their potential toxicity they should be considered as an alternative to 'middle molecules'. Patients on regular hemodialysis have retention of phenols if their post-dialysis serum creatinine is above 6-7 mg/dl. Patients on short time dialysis have high pre-dialysis neutral phenol levels. Such levels are sufficiently high to suggest a role in the genesis of neurological symptoms, anemia and bone disease. Certainly pre-dialysis free phenols reflect adequacy of dialysis.
Renal responses of the cow to alteration of the dietary intake of nitrogen and sodium chloride.
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Pakistani women's perceptions and experiences of incontinence.
AIM: To investigate the perceptions and experience of Pakistani women who have urinary incontinence problems. METHOD: Data were collected from a sample group of six Pakistani women with incontinence problems. A female Miripuri Punjabi speaker conducted and recorded semi-structured interviews with the women. The interviewer interpreted these recordings onto another tape. Data were then analysed and categorised. RESULTS: The women had low self-esteem and also felt sinful because of their incontinence. Muslim women are obliged to perform ritual cleansing and prayer five times a day. If they pass urine or faeces, or experience incontinence, they become unclean and prayer is denied until the act of ritual cleansing is repeated. The women used prayer to relieve stress caused by incontinence, but being unclean denied them this comfort, thus increasing stress. Some participants had become secretive and isolated. The women had developed three strategies to help them live with incontinence: risk reduction to reduce the number of incidents; management, which focused on coping with incontinent episodes; and problem-sharing with other women. Their inhibitions and language limitations prevented them from disclosing their problems clearly to health professionals and fully understanding advice they received. These inhibitions were reduced when they were treated by a female health professional. Having an interpreter present also increased satisfaction with treatment. CONCLUSION: To provide an effective continence service to Pakistani women with incontinence, it is necessary for healthcare professionals to understand their cultural and religious identities.
Arsenic trioxide.
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Irinotecan hydrochloride.
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A dental health project for 10-11 year olds.
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The road to conversion.
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Apply sparingly.
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