The transcription of genes could be defined as the intricate molecular manoeuvres occurring in the nuclei of cells, which allow the translation of genetic information held in the DNA into the proteins required for life. Gene transcription is the dominant control point in the production of any protein, and is initiated and regulated through the combined activities of a highly specialised set of nuclear proteins. This review examines the role of these protein “transcription factors” in the production of messenger RNA, the information intermediary produced in the nucleus, and transferred to the cytoplasm to serve as a template for protein synthesis. In combination with RNA polymerase, an extraordinary and complex enzyme required to synthesise new RNA molecules, a multitude of transcription factors combine their activities to orchestrate and control this elegant process.,Approximately 10% of melanoma cases report a relative affected with melanoma, and a positive family history is associated with an increased risk of developing melanoma. Although the majority of genetic alterations associated with melanoma development are somatic, the underlying presence of heritable melanoma risk genes is an important component of disease occurrence. Susceptibility for some families is due to mutation in one of the known high penetrance melanoma predisposition genes: CDKN2A, CDK4, BAP1, POT1, ACD, TERF2IP and TERT. However, despite such mutations being implicated in a combined total of approximately 50% of familial melanoma cases, the underlying genetic basis is unexplained for the remainder of high-density melanoma families. Aside from the possibility of extremely rare mutations in a few additional high penetrance genes yet to be discovered, this suggests a likely polygenic component to susceptibility, and a unique level of personal melanoma risk influenced by multiple low-risk alleles and genetic modifiers. In addition to conferring a risk of cutaneous melanoma, some ‘melanoma’ predisposition genes have been linked to other cancers, with cancer clustering observed in melanoma families at rates greater than expected by chance. The most extensively documented association is between CDKN2A germ line mutations and pancreatic cancer, and a cancer syndrome including cutaneous melanoma, uveal melanoma and mesothelioma has been proposed for BAP1 germ line mutations. Other medium to high penetrance melanoma predisposition genes have been associated with renal cell carcinoma (MITF, BAP1) and glioma (POT1). These associations between melanoma and other cancers hint at the possibility of common pathways for oncogenesis, and better knowledge of these pathways may improve understanding of the genetic basis underpinning familial melanoma. It is likely that ‘melanoma’ risk genes will impact on mutation screening and genetic counselling not only for melanoma but also a range of other cancers.,The main problems in identifying Treponema pallidum in tissues are optical definition contrast, and specificity. In general, fluorochrome staining provides optical definition and contrast superior to that obtained by ordinary tinctorial staining, and in theory improved resolution. Specificity is lacking however, as with other stains. In contrast, immunofluorescence should combine the optical advantages of fluorochrome staining with the immunological advantages of specificity. Since the validity of such staining depends in part upon the integrity of the antigenic components of the micro-organisms, it is customary to avoid such drastic procedures as are involved in routine fixation and paraffin embedding. The manipulation, however, of unfixed cryostat material, in contrast with that of paraffin sections suffers from two disadvantagesnamely, friability and infectivity. Published and unpublished work has shown antigenic stability in T. pallidum to a variety of procedures, both physical and chemical. Consideration of these facts led in this work to successful immunofluorescent staining after routine formalin fixation and paraffin embedding of tissues infected with T. pallidum or Treponema pertenue. Optical definition and contrast, were superior to that obtained with silver methods, but it was not possible to differentiate between these two organisms. Nevertheless immunofluorescence applied as described to paraffin sections should supply a convenient safe, and sensitive means of reappraising the histopathology of treponemal disease in patients, necropsy material, and experimental animals.
Single lung transplantation has become a therapeutic option for end-stage interstitial lung disease and obstructive lung disease. Our group recently extended this treatment to three patients with primary pulmonary hypertension. All patients had marked decreases in pulmonary artery pressures and pulmonary vascular resistance and increases in cardiac output following single lung transplantation. Spirometry, lung volumes, and diffusion capacity were not different in comparison to preoperative studies. Quantitative ventilation-perfusion scans revealed the majority of perfusion distributed to the transplanted lung, with ventilation approximately equally divided between the native and the transplanted lung. Despite ventilation-perfusion imbalance, there was no resting hypoxemia and there was no arterial oxygen desaturation with exercise. One patient expired on the 30th postoperative day due to cytomegalovirus infection of the lungs. In the remaining two patients, maximum exercise capacity following transplantation was near normal in one recipient and reduced in the second recipient. Of note, there was no evidence of ventilatory limitation or impaired oxygenation during exercise in these two recipients. Although an exaggerated exercise ventilatory response was present, this did not limit exercise performance. This report supports the use of single lung transplantation for the treatment of primary pulmonary hypertension.
Acquired immunodeficiency syndrome (AIDS) is associated with various cardiovascular disorders, such as impaired heart function; accumulation of fluid in the membrane surrounding the heart; cancer; and opportunistic infections. Four cases are described consisting of two patients with AIDS, and two patients with human immunodeficiency virus (HIV) infection. The patients developed high pressure (hypertension) in the pulmonary artery, the major blood vessel supplying the lungs, and were diagnosed as having primary pulmonary hypertension. This disorder is characterized by increased pulmonary arterial pressure resulting from structural abnormalities in the blood vessels due to some unknown cause. Two of the patients died, and the diagnosis of pulmonary hypertension was confirmed by autopsy. Primary pulmonary hypertension is associated with three pathologic characteristics: disease of the pulmonary arteries; recurrent blood clot formation in the pulmonary arteries; and obstruction of the pulmonary veins. Structural changes in the blood vessels include enlargement of the muscle layer, followed by cell overgrowth in the inner layer. There have been nine reports of HIV-infected patients with primary pulmonary hypertension. The mechanisms underlying the development of pulmonary hypertension associated with HIV infection are not clear, but may be related to a reaction of the lungs to HIV; the production of abnormal growth factors; or impaired function of the right heart ventricle due to opportunistic infection with Pneumocystis carinii. (Consumer Summary produced by Reliance Medical Information, Inc.)
After pulmonary thromboendarterectomy, performed for relief of chronic thromboembolic pulmonary hypertension, perfusion lung scans have frequently disclosed new perfusion defects in segments served by undissected pulmonary arteries. Our hypotheses were that these new postoperative defects occurred with great frequency and did not represent postoperative vessel occlusion. We retrospectively reviewed the preoperative and postoperative perfusion scans of 33 consecutive patients undergoing pulmonary thromboendarterectomy. New postoperative perfusion defects were noted in 23 of 33 patients. The incidence of new defects was increased tenfold in segments that had (1) normal preoperative angiographic findings, (2) normal preoperative radionuclide perfusion, and (3) not been entered at the time of surgery. Postoperative angiograms, available in 15 of 33 patients, documented the nonembolic, nonocclusive nature of the new perfusion scan defects. The most plausible alternate explanation for this previously undescribed finding is a redistribution of pulmonary arterial resistance induced by the thromboendarterectomy, namely, a pulmonary vascular “steal.”
Eight patients who developed pulmonary artery hypertension during the adult respiratory distress syndrome (ARDS) were treated with an infusion of prostacyclin (PGI2, 12.5-35.0 ng.kg-1.min-1) for 45 min. We examined whether reducing the right ventricular (RV) outflow pressures by PGI2 infusion would increase the right ventricular ejection fraction (RVEF) measured by thermodilution. PGI2 reduced the pulmonary artery pressure (PAP) from 35.6 to 29.1 mmHg (p less than 0.01). The cardiac index (CI) increased from 4.2 to 5.81.min-1.m-2 (p less than 0.01) partly due to an increased stroke volume. The decreased PAP together with the increased CI resulted in a fall of the calculated pulmonary vascular resistance index (PVRI, from 5.1 to 2.5 mmHg.min.m2.1-1, p less than 0.01). In the patients with subnormal baseline RVEF the increased stroke volume was associated with an increased RVEF (from 47.6% to 51.8%, p less than 0.05) suggesting improved RV function. This result was underscored by a significant relationship between the changes in PVRI and RVEF (r = 0.789, delta % RVEF = 2.11.delta PVRI-1.45). Despite an increased venous admixture from 27.8% to 36.9% (p less than 0.05) the arterial PO2 remained constant resulting in an increased oxygen delivery from 657 to 894 ml.min-1.m-2 (p less than 0.01). We conclude that short term infusions of PGI2 increased CI concomitant to improved RV function parameters when baseline RVEF was depressed. Since improved oxygen availability should be a major goal in the management of patients with ARDS PGI2 may be useful to lower pulmonary artery pressure in ARDS.
A case is described of a 37-year-old man with human immunodeficiency virus (HIV) infection who developed pulmonary hypertension, high blood pressure within the lung. The patient was admitted with symptoms of difficult breathing upon exertion and Raynaud's phenomenon, which is characterized by blood vessel constriction in the extremities upon exposure to cold temperatures or emotional stress. Weight loss, distention of the neck veins, liver enlargement, abnormal sounds in the heart and lungs, and abnormalities of the right ventricle and atrium of the heart were also observed. The patient was diagnosed with pulmonary hypertension, although no known cause could be identified. Additional laboratory tests showed that he was infected with HIV. The patient was not a homosexual or intravenous drug abuser, but reported sexual intercourse with prostitutes. The incidence of pulmonary hypertension is low, and it is unlikely that pulmonary hypertension and HIV infection developed together by chance. Thus, it is suggested that HIV infection may have caused the development of pulmonary hypertension. (Consumer Summary produced by Reliance Medical Information, Inc.)