Biomedical subjects
Publications and source records attributed to R Marotta.
Aortic transection is a frequently fatal traumatic injury. Patients who survive the initial event require rapid diagnosis and treatment. To this end, enhanced CT of the chest has been used to detect both mediastinal hematoma and direct vessel injury [1-6]. This essay shows the CT features associated with aortic transection, particularly the direct signs.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
We present seven cases of tension pneumocephalus developing after burr hole evacuation of chronic subdural haematoma. After a careful review of the literature we discuss the physiopathology, the diagnosis and the treatment of this complication of chronic subdural haematoma surgery.
Explore the source record for details and available documents.
The human immunodeficiency virus (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), directly affects the central nervous system (CNS) and often causes cognitive, motor, and behavioral changes and eventually a dementia prior to death. Suggestive evidence for the early onset of HIV-induced mental changes is derived from numerous case reports, the nature of subcortical CNS postmortem findings, and early abnormalities seen in cerebrospinal fluid, on brain computed tomography, magnetic resonance imaging, and electroencephalography, and on neuropsychological tests administered to patients with AIDS and AIDS-related complex. However, whether clinically significant cerebral impairment can precede symptoms of immunosuppression is unclear. A few studies have shown poorer performance on neuropsychological tests by asymptomatic HIV-infected subjects compared with uninfected controls, but several studies have not found this difference. To address this controversy, the current literature is reviewed, methodological problems are discussed, and recommendations are made for evaluation and treatment when early HIV-induced mental changes are suspected.
In 75 patients ultrasound (US) demonstrated fatty infiltration of the liver with diffuse increased echogenicity except for a solitary hypoechogenic area located in the quadrate lobe. The liver was also followed-up with US, computed tomography (CT), radionuclide scintigraphy, and fine needle biopsy: a skip area unaffected by steatosis was thus demonstrated. This study and further information found in literature allowed the authors to identify the particular US features which lead to a correct interpretation of these findings, which might otherwise be incorrectly diagnosed as suggestive of substitutive lesions (primary or secondary). These features are: 1) the location of skip areas, usually in the IV segment, in close relationship to a portal vessel; 2) their morphology, triangular, or inverted-V shaped; 3) the absence of mass effects upon the hepatic border and/or upon the adjacent vessels; 4) the presence of fatty liver infiltration; 5) the coexistence of a biohumoral pattern significant for diffuse hepatopathy; 6) the lack of change in US patterns during the follow-up.
The authors describe the sonographic (US) patterns of hyperplastic cholecystoses observed from January 1983 to April 1987 - 39 cases of focal extension and 12 of segmental extension--and confirm the higher sensibility of US versus oral cholecystography. Sonography (SG) allows a straight visualization of the gallbladder wall and its lesions, both in case of limited thickening of the wall (focal cholecystosis) and in case of more extensive thickening (segmental cholecystosis). To cholecystographic findings of focal lesions, SG gives additional information, adding a fundamental diagnostic element: the lack of acoustic shadowing distal to the nodular masses. Nonetheless, SG does not allow a discrimination between focal cholesterolosis and adenomyomatosis, except for particular cases, such as multiple nodular masses, and coexistence with the "comet tail" pattern--the latter due to parietal deposits of cholesterol. Furthermore, the differential diagnosis of focal cholecystoses includes some neoplasms of the gallbladder, and gallstones stuck to the wall, with no acoustic shadowing. In segmental cholecystoses, the direct evaluation of the entity and extension of the wall thickening remains a fundamental diagnostic element, even though such a morphologic detail is often integrated by the functional relieve of hypercontractility of the gallbladder wall after a fatty meal (both oral cholecystography and SG demonstrate it).
Explore the source record for details and available documents.
Labeled DNA restriction fragments excised from agarose or bisacrylylcystamine-acrylamide gels can be used for hybridization to nitrocellulose-bound DNA without eliminating the gel matrix. A gel slice containing the labeled fragment is excised, dissolved by heating at 105 degrees C (in the presence of beta-mercaptoethanol for bisacrylylcystamine-acrylamide gels), and added to the hybridization mixture. The presence of agarose or polyacrylamide in the solution does not inhibit hybridization. The method is simple, rapid, and allows complete recovery of the probe.
About half of the spontaneous petite mutants produced by wild-type Saccharomyces cerevisiae strain B (as well as by several other strains) have the same defective mitochondrial genome. Its repeat unit is a segment, 2200 base pairs (bp) long, which derives from an excision between the origins of replication ori 2 and ori 7 of the wild-type genome, and contains a hybrid ori 2-ori 7 sequence. The spontaneous petites carrying this defective ori.h genome are supersuppressive , i.e., they very rapidly compete out the wild-type genome in crosses. The main reasons for the exceptional frequency of ori.h petites are an extremely high excision frequency, due to the extended homology between the two tandemly oriented ori sequences 265 bp long and the short distance separating them. Such an excision frequency is very strongly increased in petite genomes encompassing the ori 2-ori 7 region, because of their higher concentration in these ori sequences.
Explore the source record for details and available documents.
Zein messenger RNAs from maize endosperm were purified by successive oligo(dT)-cellulose chromatography and sucrose gradient centrifugation. Polyacrylamide gel electrophoresis under denaturing conditions revealed the presence of two size classes of zein messenger RNAs of Mr 3.5 x 10(5) and 4.10 x 10(5). The mRNA was shown to synthesize the major zein polypeptides, to have a base composition characteristic of a poly(A)-containing RNA and to be transcribed by reverse transcriptase into complementary DNA. The r0t1/2 of the hybridization curve of cDNA hybridized to an excess of mRNA was shown to be 7 x 10(-2) M . s indicating that about 15 non-cross-hybridizing sequences are present in the zein mRNA preparations. The kinetics of cDNA annealing with an excess of maize DNA from 2 n cells suggest a ten-times reiteration of each mRNA sequence. This result is confirmed from saturation experiments, where in cDNA excess to DNA, the number of zein genes per haploid maize genome was estimated as about 120 copies. Similar experiments carried out on DNA from normal and mutant endosperms (3n cells) indicate the absence of large amplifications or deletions of zein genes in the tissue devoted to zein synthesis.
BACKGROUND: Many diverse pathogenic mitochondrial DNA (mtDNA) mutations have been described since 1988. The Melbourne Neuromuscular Research Institute (MNRI) has undertaken diagnostic detection of selected mtDNA mutations since 1990. MtDNA mutations screened have included point mutations associated with Leber's hereditary optic neuropathy (LHON; G3460A, G11778A and T14484C), mitochondrial encephalopathy lactic acidosis and stroke-like episodes (MELAS; A3243G), myoclonus epilepsy and ragged red fibres (MERRF; A8344G) and Leigh's syndrome/neuropathy ataxia retinitis pigmentosa (LS/NARP; T8993C/G). Samples have also been screened for deletions/ rearrangements associated with Kearns-Sayre syndrome (KSS) and chronic progressive external ophthalmoplegia (CPEO). AIMS: To present an audit of the MNRI mtDNA diagnostic service between 1990 and 2001, encompassing 1725 referred patients. METHODS: The detection techniques carried out included polymerase chain reaction amplification of mtDNA combined with restriction fragment length polymorphism analysis for mtDNA point mutation detection, supplemented with selected sequence analysis and Southern blots for the detection of deletions/ rearrangements. Tissues tested included blood, hair and skeletal muscle. RESULTS: Of the 1184 patients screened for MELAS A3243G, 6.17% were positive for the mutation, whereas for MERRF A8344G, 2.21% carried the mutation and for LS/NARP T8993C/G, 0.32% carried the mutation. The outcomes for the LHON mutations were G11778A, 6.60%, T14484C, 5.76% and G3460A, 0.29%. Of the patients referred for KSS and CPEO, 17.72% had deletions/rearrangements. CONCLUSIONS: Overall, the detection rate of mtDNA point mutations was low. The protean clinical features of mitochondrial disorders and the frequency of partial phenotypes lead to requests for tests in many patients with a relatively low likelihood of mtDNA mutations. An improved algorithm could involve mutation screening appropriate to the phenotype using sequencing of selected mtDNA regions in patients with a high likelihood of mtDNA disease. Features increasing the likelihood of mtDNA mutations include the following: (i) a typical phenotype, (ii) a maternal inheritance pattern and (iii) histochemical evidence of mitochondrial abnormality in the muscle biopsy. Efficient laboratory diagnosis of mtDNA disease involves good communication between the physician and laboratory scientists, coupled with screening of the appropriate tissue.
Explore the source record for details and available documents.
Explore the source record for details and available documents.