Electrode Configurations for a Respiratory Impedance Measurement Suitable for Rate Responsive Pacing

A rate responsive cardiac pacemaker will benefit the patient only if the input parameter is a reliable indicator of exercise, Part of the reliability is dependent upon selection of the best physiological parameter and part is dependent upon the measurement technique. Twenty-six patients have been studied in order to ascertain the best measurement configuration for an intravascular impedance respiratory monitor. Four electrode configurations have been examined at rest and during exercise. The results have been compared using measures of sensitivity and specificity. The ideal configuration requires that a current field be established between the right ventricular blood and the pacemaker case. And, that voltage sensing be done between an electrode in the SVC and the pacemaker case.     

MUTATION OF THE VHL GENE IS ASSOCIATED EXCLUSIVELY WITH THE DEVELOPMENT OF NON-PAPILLARY RENAL CELL CARCINOMAS

To define the possible role of the VHL gene in the development of sporadic renal cell carcinomas, 91 different parenchymal tumours of the kidney have been investigated for mutation of the VHL gene by single strand conformation polymorphism (SSCP) and/or heteroduplex (HD) techniques. Chromosome 3p deletion was detected in 98 per cent of non-papillary renal cell carcinomas and in 25 per cent of chromophobe renal cell carcinomas. In 22 of the 43 non-papillary renal cell carcinomas, abnormally migrating DNA bands were detected by SSCP and/or HD analysis. No mobility shift was seen in any of the 23 chromophobe renal cell carcinomas. In addition, 15 papillary renal cell tumours and ten renal oncocytomas, which are characterized by genetic changes other than loss of chromosome 3p sequences, were analysed for mutation of the VHL gene. None of these tumours showed abnormal migration patterns. The results indicate that mutation of the VHL gene is associated exclusively with the development of non-papillary renal cell carcinoma.     

Phosphate Partition in the Erythrocytes of Normal Newborn Infants and Infants with Erythroblastosis Fetalis. III. P32 Uptake and Incorporation

The uptake and incorporation of P³²O₄ by the cord blood erythrocytes ofnormal and erythroblastotic infants and the erythrocytes of adults was studiedby incubating specimens in ACD at 37 C. in air. The uptake of p³² from theplasma was slower in the infants than in the adults. It was possible to demonstrate an initial "fast" phase followed by a "slow" phase in all the plasma p³²uptake experiments. The half-value time and the percentage turnover perminute indicated greater activity in the adults compared to the infants. Thebalance of movement of phosphorus was from red cells to plasma in all theexperiments. No striking differences in phosphate metabolism were demonstrated between the normal and erythroblastotic newborns, except for thelarge turnover in µM of P per minute by the red cells of the latter during thefirst 20 minutes of incubation.

Labeling of intraerythrocytic inorganic phosphorus (P_i), adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG) proceeded more slowlyin the infants than in the adults. The labeling of the erythrocyte 2,3-DPG of allthe infants lagged far behind P_i and ATP whereas in the adults the r.s.a. of2,3-DPG had equalled or exceeded the r.s.a. of P_i and ATP in four hours. Itis suggested that there is decreased synthesis of phosphoglycerates by theerythrocytes of the newborn which may be due to a lower level of glyceraldehyde-3-phosphate dehydrogenase activity.

Accepted on January 11, 1962     

Increased Thymic Size and Thymocyte Interleukin 2 Production in Androgen-Resistant Mice

The functional significance of androgen receptors in thymocytes is unknown. To investigate whether such receptors might mediate androgen-induced effects on thymocyte proliferation or differentiation we examined mice bearing a known defect in the gene coding for the androgen receptor. This mutation, termed testicular feminization (Tfm/Y), renders these mice resistant to the action of androgenic hormones. Testicular feminization mice were found to have large thymuses that were an average of 2.8 times as heavy as those of their unaffected male litter mates, and contained up to 36 times as many thymocytes. Similar findings were observed when Tfm mice were compared with C57Bl/6 control mice. Thymocytes from androgen-resistant mice produced several times more interleukin 2 in culture than did thymocytes from control mice. A small but significant reduction in the population of cells bearing neither CD4 nor CD8 surface markers ('double negatives') was observed in the androgen-resistant mice. These data indicate that androgen resistance is associated in the Tfm/Y mouse with alterations in thymocyte number, phenotype, and function that may be attributable to lack of androgen action during thymic development.     

A pilot study of central venous catheter survival in cancer patients using low-molecular-weight heparin (dalteparin) and warfarin without catheter removal for the treatment of upper extremity deep vein thrombosis (The Catheter Study)

BACKGROUND: Central venous catheters in patients with cancer are associated with development of deep vein thrombosis (DVT); however, there is no accepted standard treatment. OBJECTIVES: To assess the safety and effectiveness of a management strategy for central venous catheter-related DVT in cancer patients consisting of dalteparin and warfarin without the need for line removal. PATIENTS/METHODS: Patients older than 18 years of age with an active malignancy and who had symptomatic, acute, objectively documented UEDVT were eligible. Patients were treated with dalteparin 200 IU kg(-1) per day for 5-7 days and warfarin with a target International Normalized Ratio of 2.0-3.0. Patients were followed for 3 months for recurrent venous thromboembolism, major hemorrhage and survival of the central venous catheter. RESULTS: There were 74 patients (48 males). The average age was 58 years. There were no episodes of recurrent venous thromboembolism and three (4%) major bleeds. No lines were removed because of infusion failure or recurrence/extension of DVT. CONCLUSION: Treatment of UEDVTs secondary to central catheters in cancer patients with standard dalteparin/warfarin can allow the central line to remain in situ with little risk of line failure or recurrence/extension of the DVT.     

Nifedipine in the treatment of Raynaud''s phenomenon in patients with systemic sclerosis

A double-blind, placebo-controlled, cross-over trial of nifedipine 10 mg three times daily for 6 weeks, in 10 patients with Raynaud's phenomenon secondary to systemic sclerosis, is reported. A significant reduction in the duration of attacks of Raynaud's phenomenon was observed. Nifedipine therapy also reduced the number and severity of attacks of Raynaud's phenomenon and the development of new digital ulcers, and increased the digital blood flow, but none of these changes was statistically significant. No alteration in red blood cell deformability or leukocyte chemiluminescence was observed during nifedipine treatment.