Applications of endocytosis research to drug delivery.
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Biomedical subjects
Publications and source records attributed to G Wilson.
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Plasticized polyvinylchloride film has been used in this burns unit for a long time for dressings before the ward round, before surgery, and when the burned patient is transferred from the casualty department to the burns unit. Plasticized polyvinylchloride film is easy to use, safe, and causes no pain. Most importantly, in the present financial climate, it is cheap.
The modification genes of Flavobacterium okeanokoites and Haemophilus galinarum have been cloned into the vector pBR322 and expressed in Escherichia coli cells. FokI methylase gene is contained on a 3.80 kb piece of F. okeanokoites DNA. Plasmid constructs carrying this fragment of DNA are resistant to digestion by FokI restriction endonuclease but are sensitive to cleavage by HindIII, EcoRI and PstI. Unmodified lambda DNA molecules, exposed in vitro to cell extracts prepared from cells habouring this plasmid, became resistant to digestion by FokI. The smallest HgaI methylase clone carries the pBR322 plasmid containing a 3.50 kb piece of H. galinarum DNA. This plasmid is resistant to digestion by HgaI. Neither the FokI nor the HgaI restriction endonuclease was detected in either clone. This is the first report of cloning modification genes whose protein products recognise asymmetric nucleotide sequences.
The case of a burned patient, whose fluid management was complicated by the development of toxic epidermal necrolysis, a condition which itself may mimic a burn, is presented. The possible causes, together with the diagnostic and therapeutic problems posed by this combination of ailments, are discussed.
The role of combined two-dimensional and pulsed Doppler echocardiography in the postoperative assessment of patients with total anomalous pulmonary venous connection was evaluated. Twenty-two cases with a median age of 9.5 weeks at the initial examination were evaluated. Serial ultrasound examinations were performed throughout the study period. The ultrasound results were compared with chest radiographs obtained during the same period. Of the 22 patients, 16 had normal pulmonary venous flow profiles characterized by low-velocity laminar flow. Of this group 12 had persistent radiographic postoperative pulmonary edema that cleared in all by 4 months. Six patients with pulmonary venous obstruction were identified, the diagnosis being confirmed at catheterization or autopsy. The venous flow pattern in this group was uniformly high velocity and turbulent. It was possible to localize the site of obstruction in each case. Although pulmonary edema was present in each patient, the chest radiograph did not provide reliable information as to the exact site of obstruction. Combined two-dimensional and Doppler echocardiography is a useful adjunct in the postoperative evaluation of patients with total anomalous pulmonary venous connection.
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MR images of the intratemporal portion of the facial nerve were obtained with surface coils using a 0.3-T permanent magnet whole-body imaging system. Various 2DFT spin-echo pulse sequences were used to produce 5-mm thick sections with 0.5-mm pixels on a 512 X 512 acquisition matrix. The MR images from normal volunteers were correlated with cryosection specimens of three fresh human cadavers. The seventh nerve was followed in the internal auditory and fallopian canal and through temporal bone to the stylomastoid foramen. The entire labyrinthine, tympanic, and mastoid portions, as well as the geniculate ganglion, could be shown with appropriate scan planes. MR produces excellent images of the facial nerve with high-contrast resolution. Unlike CT, no beam-hardening artifact from the temporal bone is apparent. MR should be a sensitive study for the evaluation of intratemporal facial nerve disease.
High-resolution surface-coil MR imaging reveals intricate anatomic detail of the cervical spinal canal and its neurovascular contents. Appreciation of the normal neurovascular anatomy provides a scientific foundation for the detection of disease. Sagittal, axial, and oblique MR images of normal subjects were correlated with comparable anatomic sections obtained with a cryomicrotome whole-organ sectioning technique. The anterior epidural venous plexus is a prominent structure in the cervical spinal canal and was consistently identified both with cryomicrotomy and with MR in sagittal and axial planes. Epidural veins can be displaced and distorted in patients with cervical disk disease. Nerve roots including dorsal and ventral rootlets were consistently identified on axial images coursing through the subarachnoid space. Oblique-plane imaging showed nerve roots "en face" in their respective foramina; this may be a useful imaging technique in the diagnosis of nerve root impingement.
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The flow-cytometry results of solid, human tumours are reported which were labelled with Bromodeoxyuridine in vivo. The preparation of the single cell suspension is prescribed. The S-phase percentage could be determined exactly in all cases but one. It is a rapid procedure which gives results in one day and the in vivo labelling had no adverse effects.
Flow cytometric DNA analysis was performed on both fresh and on paraffin embedded samples obtained by gastroscopic biopsies in 5 patients with histologically normal gastric mucosa (20 specimens) and by radical gastrectomies in 9 cases of human gastric cancer (36 specimens). Ploidy and the distribution of cells in the different cell cycle phases were estimated. Results from fresh tissue were compared with those from paraffin embedded material. All the samples of normal mucosa showed a diploid modal DNA content. Unimodal DNA distribution was found both in fresh and paraffin embedded material of 3 well differentiated gastric adenocarcinomas, whereas the remaining 6 tumors (1 moderately differentiated, 4 poorly differentiated and 1 undifferentiated adenocarcinomas) showed aneuploidy. The percentage of cells in S phase in normal tissue and in tumors were respectively 9.0% and 11.9% in the fresh material, and 10.0% and 15.0% in the paraffin embedded material. No statistically significant differences were found between fresh and paraffin embedded samples, whereas the proliferative activity was, in both cases, statistically higher in tumors than in normal mucosa (p less than .01 and p less than .001 respectively). The quality of DNA flow cytometry from paraffin embedded material was comparable with that from fresh samples.
DdeI, a Type II restriction-modification system from the gram-negative anaerobic bacterium Desulfovibrio desulfuricans, recognizes the sequence CTNAG. The system has been cloned into E. coli in two steps. First the methylase gene was cloned into pBR322 and a derivative expressing higher levels was constructed. Then the endonuclease gene was located by Southern blot analyses; BamHI fragments large enough to contain the gene were cloned into pACYC184, introduced into a host containing the methylase gene, and screened for endonuclease activity. Both genes are stably maintained in E. coli on separate but compatible plasmids. The DdeI methylase is shown to be a cytosine methylase. DdeI methylase clones decrease in viability as methylation activity increases in E. coli RR1 (our original cloning strain). Therefore the DdeI system has been cloned and maintained in ER1467, a new E. coli cloning strain engineered to accept cytosine methylases. Finally, it has been demonstrated that a very high level of methylation was necessary in the DdeI system for successful introduction of the active endonuclease gene into E. coli.
A study was performed evaluating magnetic resonance imaging (MRI) in 35 patients with intractable complex partial seizures in whom computed tomographic (CT) scans showed no focal abnormalities. These results were correlated with positron emission tomography evaluation (PET), the electroencephalographic ictal onset, and findings during pathological examination. Seven patients had structural lesions that were epileptogenic, detected by MRI; the lesions were tuberous sclerosis, astrocytomas, or hamartomas. Three of these 7 patients underwent PET scanning, which was normal in all. Of 18 patients with mesial temporal sclerosis, 10 were shown by PET to have temporal lobe hypometabolism, though all 18 had normal MRI findings. The results indicate that MRI contributes information to that provided by CT and PET, by detecting nonsclerotic epileptogenic lesions of the temporal lobe.
We have observed that plasmids containing certain cloned modification methylase genes of type II restriction-modification systems cannot be transformed into many laboratory strains of Escherichia coli K-12. The investigation of this phenomenon, reported here, has revealed (i) DNA containing 5-methylcytosine is biologically restricted by these strains, while DNA containing 6-methyladenine is not; (ii) restriction is due to two genetically distinct systems that differ in their sequence specificities, which we have named mcrA and mcrB (for modified cytosine restriction). Since 5-methylcytosine containing DNA is widespread in nature, the Mcr systems probably have a broad biological role. Mcr restriction may seriously interfere with molecular cloning of 5-methylcytosine-containing foreign DNAs. The Mcr phenotypes of some commonly used strains of E. coli K-12 are reported.
Utilization of physician services by initial subscribers to a Canadian consumer-sponsored medical care plan was examined for the period 1965-1979. After stratification by sex and age, 1,046 individuals aged 18-44 years were sampled and their records abstracted to yield the annual number of in-plan physician visits. The most frequently attending 10% of patients generated almost 30% of all visits. Moreover, those who initially made most frequent use of physician services persisted in doing so over the 15-year period. Utilization patterns differed between the sexes. Women, with a median of 40 visits, made more frequent use of services than men, with a median of 27 visits. Among men, the group that was oldest at enrollment utilized services more heavily than their younger counterparts, and this increased relative utilization became more pronounced with time. Corresponding effects were not seen in women, even after adjustment for prenatal visits. Adjustment for prenatal visits also had only a minimal effect on the frequency and duration of nonattendance. Ascertainment of out-of-plan utilization indicated that for the most recent year of follow-up, 20% of the patients made at least one out-of-plan visit. Although this had little effect on patients' relative utilization status, it had a substantial effect on the identification of nonattenders.
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