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Biomedical subjects

R Hull

Publications and source records attributed to R Hull.

At least 199 records · Page 11Linked to original sources
PubMed1981

Characterisation of cauliflower mosaic virus DNA sequences which encode major polyadenylated transcripts.

Cauliflower mosaic virus DNA sequences which encode two major polyadenylated RNA species, the 1.9 kb messenger RNA for the 62,000 MW virus inclusion body polypeptide and 35S RNA, were mapped using the nuclease 51 procedure. The 1.9 kb RNA has an eleven nucleotide leader sequence transcribed from alpha-strand DNA located at co-ordinate 0.72 m.u. (map units), immediately upstream of the AUG initiation codon of reading frame VI. The 3'-end of 1.9 kb RNA maps at 0.95 m.u. and is co-terminal with the 3'-end of 35S RNA, a complete transcript of the DNA alpha-strand. The 5'-end of 35S RNA maps at 0.93 m.u. and is located upstream of the discontinuity G1 (zero m.u.) in the alpha-strand and some 200 nucleotides upstream of the sequence encoding its own 3'-terminus.

Base Sequence↗
PubMed1981

Cost effectiveness of clinical diagnosis, venography, and noninvasive testing in patients with symptomatic deep-vein thrombosis.

Until the past decade, physicians were content to base therapeutic decisions on the clinical diagnosis of deep-vein thrombosis. Subsequently, numerous studies demonstrated that clinical diagnosis of this condition is nonspecific. Although many now use objective methods to diagnose venous thrombosis, their relative cost and effectiveness have not been adequately studied. We performed a cost-effectiveness analysis of 516 patients with clinically suspected venous thrombosis who were evaluated by clinical diagnosis, venography, and the less invasive combination of impedance plethysmography and leg scanning. We used this analysis to rank these alternative approaches in terms of both cost and effectiveness. The results indicate that clinical diagnosis is cost ineffective. Venography is cost effective--more so when applied as an outpatient investigation. Impedance plethysmography plus leg scanning is a practical, less invasive alternative to outpatient venography. The cost of inpatient diagnosis is likely to remain the major cost; thus, emphasis should be placed on outpatient diagnostic procedures.

Ambulatory Care↗
PubMed1981

The low specificity of postoperative perfusion lung scan defects.

Ventilation and perfusion lung scans were performed preoperatively and postoperatively in 169 patients and classified blindly according to preset criteria. Perfusion lung scan abnormalities were present in 25 (15%) of the preoperative scans and 42 (25%) of the postoperative scans; 16 (38%) of the 42 abnormal postoperative scans were identical to the preoperative scans. Perfusion defects indicating a "high probability" of pulmonary embolism (lobar or segmental defects) were present in 5 preoperative scans and 10 postoperative scans; the 10 postoperative scans were classified as showing "definite" (5), "possible" (1) or "no" (4) pulmonary embolism on the basis of the preoperative scan and the ventilation scan; none of the 10 patients had clinical evidence of pulmonary embolism. Venous thrombosis was present in 12 patients, including 4 of the patients whose lung scans showed definite pulmonary embolism. Thus, postoperative perfusion lung scan defects are potentially misleading even when large.

Adult↗
PubMed1981

Clinical validity of a negative venogram in patients with clinically suspected venous thrombosis.

Although it is generally accepted that negative venography excludes deep vein thrombosis (DVT) in patients in whom it is clinically suspected, there is no evidence to support this conclusion. To test the correctness of withholding anticoagulant therapy in these patients, we followed 160 consecutive patients who had clinically suspected DVT and negative venograms to determine the frequency of postvenographic DVT. Anticoagulant therapy was withheld in all patients. No patient died or developed pulmonary embolism during 3 months of follow-up. Two of the 160 patients (1.3%) attended the clinic on an emergency basis during follow-up with new symptoms of DVT and in both patients, DVT was confirmed by objective testing. These events developed within 5 days of venography, which suggests that they were induced by venography. Nevertheless, the findings indicate it is safe to withhold treatment in patients with clinically suspected DVT and negative venograms.

Adolescent↗
PubMed1981

Replacement of venography in suspected venous thrombosis by impedance plethysmography and 125I-fibrinogen leg scanning: a less invasive approach.

Noninvasive diagnostic testing is gaining acceptance in the evaluation of patients with clinically suspected venous thrombosis. Although clinically useful, all these tests have limitations, and the safety of basing therapeutic decisions on their outcome has not been assessed. We have done a prospective study of 322 symptomatic patients to ascertain the safety of replacing venography with impedance plethysmography and leg scanning. To provide a diagnostic reference, we did venography in all patients but withheld anticoagulants if the noninvasive tests were negative irrespective of the results of venography. None of the 163 patients with negative noninvasive tests died or developed clinical pulmonary embolism during 3 months' follow-up, confirming the safety of this approach. In two, clinically evident postvenographic venous thrombosis developed, confirmed by repetition of these objective tests. Also, the positive predictive values indicate that therapeutic decisions can be based on a positive noninvasive outcome in patients without clinical disorders known to produce false-positive results.

Adolescent↗
PubMed1979

Warfarin sodium versus low-dose heparin in the long-term treatment of venous thrombosis.

Acute deep-vein thrombosis is usually treated with intravenous heparin for a number of days, then with oral anticoagulants for weeks to months. We have compared adjusted-dose warfarin sodium with fixed low-dose subcutaneous heparin in the prevention of recurrent deep-vein thrombosis. Sixty-eight patients with acute deep-vein thrombosis confirmed by venography were treated with intravenous heparin and then randomized to secondary prophylaxis. Nine of 35 patients receiving subcutaneous heparin, but none of 33 receiving warfarin sodium, had new episodes of objectively documented venous thromboembolism (P = 0.001). Seven patients on warfarin sodium experienced bleeding complications (of which four were major), as compared with no patients receiving subcutaneous heparin (P less than 0.005). Thus, adjusted-dose warfarin sodium is more effective than low-dose subcutaneous heparin in preventing recurrent venous thromboembolism, but its use is accompanied by a significant risk of bleeding.

Acute Disease↗
PubMed1979

The polarity of the cauliflower mosaic virus genome.

We have demonstrated that the 5' termini of the DNAs of cauliflower mosaic virus (CaMV) isolates CM4-184 and Cabb B-JI have free hydroxyl groups accessible for phosphorylation using polynucleotide kinase. This has enabled us, using the Cabb B-JI isolate, to label and identify the 5' nucleotides. Digestion of 5' terminally labelled DNA with EcoRI restriction endonuclease revealed that only three of the eleven single-stranded EcoRI fragments were labelled, those situated adjacent to the three known gaps in the double-stranded genome. Identification of the labelled fragments indicated the polarity of the genome. Hybridization experiments using RNA transcripts from infected leaves gave results consistent with the polarity data and confirmed the direction of transcription. Transcription on the largest DNA strand (alpha strand) is initiated between map units 0.24 and 0.30 and terminates between map units 0.0 and 0.24.

DNA Restriction Enzymes↗
PubMed1979

Rhabdoviridae. Report of the Rhabdovirus Study Group, International Committee on Taxonomy of Viruses.

The family Rhabdoviridae comprises approximately 75 viruses infecting vertebrates, invertebrates and plants. The main characteristics of the member viruses are: (i) the viruses infecting vertebrates and invertebrates are bullet-shaped and the viruses infecting plants are usually bacilliform; (ii) the viruses have particle lengths varying from 130 to 380 nm and widths varying from 60 to 95 nm; (iii) the viruses possess unit-membrane envelopes from which protrude spikes 5 to 10 nm long; (iv) the viruses have precisely coiled helical nuecleocapsids with a diameter of approx. 50 nm; (v) most of the viruses which have been studied contain 5 proteins; the prototype, vesicular stomatitis virus, contains proteins designated L (large), G (glycoprotein), N (nucleoprotein), NS (nonstructural) and M (matrix); N or NS is phosphorylated in most members which have been studied; (vi) the viruses contain single-stranded RNA which is transcribed into several messenger RNA species with sizes corresponding to the structural proteins; (vii) the nucleocapsid contains the RNA-dependent RNA polymerase and is infectious; and (viii) many of the viruses produce morphologically distinct defective-interfering (T) particles.

RNA, Viral↗
PubMed1978

Impedance plethysmography: the relationship between venous filling and sensitivity and specificity for proximal vein thrombosis.

We investigated the hypothesis that the diagnostic accuracy of impedance plethysmography (IPG) for thrombosis of the popliteal or more proximal veins increases with enhanced venous filling. Venous filling was increased by prolonging cuff occlusion and by sequential testing. IPG and vengography were performed on 169 legs with and 317 legs without proximal vein thrombosis. The sensitivity and specificity of IPG rose significantly with increased venous filling. Changes in venous filling were associated with corresponding changes in emptying in normal legs, but not those with proximal vein thrombosis, so that the regression lines relating venous filling and emptying in normal and abnormal legs diverged significantly (P less than 0.001). If the IPG sequence had been terminated after only a single 45 second occlusion time test, sensitivity would have deteriorated by 10% and specificity by 20%. These observations indicate that the accuracy of IPG can be significantly enhanced if optimal venous filling is obtained.

Evaluation Studies as Topic↗