This month in J Lab Clin Med
2001; Elsevier BV; Volume: 138; Issue: 5 Linguagem: Inglês
10.1067/mlc.2001.119662
ISSN1532-6543
Autores Tópico(s)Economic and Financial Impacts of Cancer
ResumoA wide variety of viral and bacterial pathogens may be implicated in otitis media and in sinusitis. The ones of greatest interest are the ones for which one can intervene to clinical benefit; particular attention has focused on Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhali. It's been difficult to study these organisms in human disease, because the site of infection isn't that easily sampled, and because the normal flora of the pharynx may overgrow the pathogens of interest if one samples from an alternative site. This becomes particularly problematic in studies of asymptomatic carriage of the organisms; in that circumstance, the number of pathogenic organisms may be low and there is no inflammatory fluid to sample more selectively (eg, by tympanocentesis). An ongoing study of upper respiratory infections at the University of Virginia afforded an opportunity to compare strategies for detecting the presence of the three organisms mentioned above. Eighteen children were already having weekly nasopharyngeal washings taken; Sharon Dudley and her colleagues placed samples of these washings on nonselective and selective culture media (see page 338). The two nonselective media were sheep blood agar and “chocolate” agar. The three selective media were blood with gentamicin (to select for S pneumoniae ); chocolate agar with vancomycin, bacitracin, and clindamycin (to select for H influenzae ); and blood with amphotericin B, vancomycin, trimethoprim, and acetazolamide (to select for M catarrhali ). For each organism, the selective agar yielded more positive cultures than did the nonselective agar. S pneumoniae was found in 44% of samples on selective agar versus 25% on standard agar; H influenzae was found in 31% of samples on selective agar versus 9% on standard agar; M catarrhali was found in 56% of samples on selective medium versus 37% on nonselective medium. Eighty percent of samples had one or more pathogens detected with selective agars as compared with 58% with standard agars. Thus the use of standard culture techniques substantially underestimates the incidence of colonization with these organisms. Liver transplantation is a huge and morbid surgical procedure; although outcomes are good for many indications, the limited supply of donor organs means that many good candidates are denied this therapy; moreover, it can be offered only to patients who are likely to survive its rigors. The ability to transplant isolated hepatocytes (or hepatocyte precursors) could provide an answer to several of the problems with transplantation of the whole organ. Cells could be banked more readily than can whole organs; the surgical procedure would be less expensive and less dangerous. To date, there have been only a few reports of successful liver cell transplantation, generally in the context of bridging the gap in time between life-threatening hepatic failure and the availability of a suitable organ for transplantation. The practical development of this approach has been limited by several factors. For example, it is hard to identify patients for whom an attempt at liver cell transplantation would not be denying them or delaying the standard therapy of whole-organ liver transplantation. For another, the highest quality liver cells are presumably in the livers that are the best ones for transplantation as whole organs—the source is largely self-extinguishing. A technique for growing liver cells in tissue culture, expanding a small sample to a potentially useful inoculum, could broaden the potential applications of the technique and could enable the studies needed to learn how to make it work. The current state of research in this area is reviewed for us this month by Drs K. J. Allen of the Royal Children's Hospital of Melbourne and H. E. Soriano of the Chicago Children's Memorial Hospital (see page 298). In the last 20 years, much has been learned concerning the regulation of pressure in the pulmonary vascular circuit. The most important factor is the calcium balance of the vascular smooth muscle cells; this in turn is responsive to nitric oxide status, prostanoid metabolism, an endothelially derived hyperpolarizing factor, and the presence or absence of hypoxia. The picture is complete enough to allow one to start thinking about primary pulmonary hypertension in a more pathophysiologic way and thus to start moving toward a more pathophysiologic approach to its prevention and treatment. This body of knowledge has been reviewed for our readers in two essays by Dr Horst Olschewski and several of his associates from the Justus-Liebig University in Giessen, Germany. The first of those essays stresses the underlying pathophysiology and appears in the current issue (page 287). The second of the essays explores in more detail the possible therapeutic implications of recent developments and will be presented in next month's issue. Sudden ischemic injury to a previously well kidney is a major clinical problem, especially in organ transplantation. That is, the donor kidney being explanted is predictably exposed to a period of ischemia, and delayed recovery of function after implantation into the recipient is a common event. Although most recipients recover good function after a period of acute kindey failure, the occurrence of kidney failure in the early post-transplant phase predicts a higher risk of eventual graft failure. Understanding the process of ischemic injury and the process of recovery could enable one more reliably to prevent the former and hasten the latter. Moreover, it could be important to recognize which parts of the injury sequence might be beneficial—by ensuring the removal of irreparably damaged cells—and which parts might be interrupted to clinical benefit. Dr Rainer Oberbauer —working with several associates from the University of Vienna, Stanford University, and the University of Innsbruck—examined apoptotic markers in rats subjected to a 30-minute ischemic insult to a single kidney (the other kidney having been removed earlier in the same procedure). At each of several time points thereafter (up to 20 weeks), 5 experimental animals and 5 sham-operated controls were killed, and the kidneys were examined. As described beginning on page 343, a bit over 8% of tubular cells in the kidneys subjected to ischemia showed DNA fragmentation by TUNEL staining on the first post-insult day, while control animals had too few to enter into a 1000-cell count. A modest increase was still pres-ent a week after the ischemia. At that time, mRNA expression for some apoptosis regulators was also measured in whole kidney extracts: expression for the apoptosis inhibitory genes bcl-xL and bcl-2 as well as the apoptosis promoter bax was significantly reduced. The authors also used immunohistochemistry to look for locally selective expression of apoptotic regulators; they found that bcl-2 was underexpressed in the distal tubule, whereas it was up-regulated in the proximal tubule. The apoptosis promoter bax showed the opposite pattern, with its strongest expression in the distal tubule. After clearance of the apoptotic cells, a phase of cellular proliferation ensued. Unlike the human transplant recipients, the rats did not recover and retain good kidney function. Proliferation continued until tubular dilation and kidney failure supervened (by 20 weeks). The authors conclude that activation of apoptosis is an important mechanism for the elimination of cells injured by transient renal ischemia and that the state of activation reflects differential regulation of pro- and anti-apoptotic regulators. Learning to understand and regulate this process better may one day be of clinical use in transplantation. “Alcoholic liver disease” has long been on the textbook list of causes for macrocytosis and anisocytosis. Indeed, the patient with alcoholic liver disease is likely to have several clinical problems that may be associated with red blood cell abnormalities, ranging from altered cholesterol/phospholipid balance to nutritional insufficiencies. But “alcoholic liver disease” is a pretty nonspecific category, and one needs to be able to decide which alcoholic patients with liver disease need further work-up if they are found to be macrocytic. Of course, one may clinically have a number of clues that suggest more is going on, so the decision is sometimes easy. Dr Shigeo Maruyama and several associates from the Saiseikai Gotsu General Hospital (Shimane, Japan) evaluated red blood cell indices and vitamin status in 423 consecutive patients with liver disease (see page 332). As one would expect, they found that many of the patients had red cell macrocytosis and many of them had folic acid deficiency. They found further that mean cell volume and red blood cell distribution width index were higher in patients with alcoholic liver disease than in patients with non-alcoholic liver disease and were higher in patients with cirrhosis than in patients without cirrhosis. Actual macrocytic anemia was common only in cirrhotic patients, in whom its incidence and severity correlated with the severity of the liver disease (Child-Pugh score). Perhaps the most interesting observation was that macrocytosis correlated with alcohol consumption; although it also correlated inversely with the serum folic acid level, a high ethanol intake was often associated with macrocytosis even in the face of a normal serum folate. Folic acid levels rose and mean cell volumes declined in patients who became abstinent. These findings fit with many previous observations and with many observers' biases, but they bring larger numbers to some of the questions than have previous studies. They support the notion that alcohol's direct marrow toxicity is great enough to cause macrocytosis, even in the absence of vitamin deficiency, and that liver disease may predispose to macrocytosis when it is severe enough and of long enough duration to have produced cirrhosis. For many years it has been possible for a protein to be “identified” by a reagent antibody without one having a lot of information about it. With the development of monoclonal reagent antibodies, it became common to be able to identify cell types quite confidently, even though one sometimes knew nothing about the target antigen other than the cellular specificity of its distribution. As the techniques for the study and amplification of nucleic acids have advanced, it has become possible more readily to ask questions about the target antigen. One may gain information about conformation, amino acid sequence, and similarity to other known and reported antigens. An example of such an exercise appears in this month's Journal. Dr A. N. Solovey and colleagues at the University of Minnesota sought information about the target of a monoclonal antibody designated P1H12, which has been found to identify endothelial cells from all sizes of blood vessels, as well as circulating endothelial cells. They worked with a human umbilical vein endothelial cell cDNA library, expressing the components in Chinese hamster ovary cells. They then selected the cells that were positive when screened by P1H12 and sequenced the cDNA in them. This DNA sequence was then compared with known sequences, and it was found to be virtually identical with that for a melanoma cell surface antigen (CD146). A number of experiments then sought to characterize the function of the antigen by using both CD146 and P1H12 antibodies. The antigen was important in a number of cell-to-cell adhesive interactions as well as in the phosphorylation of FAK and NFκB distribution; the density of the antigen differed among types of endothelial cells. This report may be found beginning on page 322. Bacterial pathogens of otitis media and sinusitis: Detection in the nasopharynx with selective agar mediaThe Journal of Laboratory and Clinical MedicineVol. 138Issue 5PreviewCarriage rates for the bacterial pathogens associated with otitis media (Streptococcus pneumoniae [SP], Hemophilus influenzae [HI], and Moraxella catarrhalis [MC]) are of interest. Culture on three selective agars was compared with culture on two standard agars to determine the more accurate method for detection of these species in the nasopharynx of healthy children. Weekly samples were obtained in winter from 18 healthy children (ages 1 through 9 years) as part of a longitudinal study. A 0.1-mL sample of 116 nasopharyngeal aspirate/washes was inoculated onto each of five agars. Full-Text PDF Liver cell transplantation: The road to clinical applicationThe Journal of Laboratory and Clinical MedicineVol. 138Issue 5PreviewJ Lab Clin Med 2001;138:298-312. Full-Text PDF Physiologic basis for the treatment of pulmonary hypertensionThe Journal of Laboratory and Clinical MedicineVol. 138Issue 5PreviewJ Lab Clin Med 2001;138:287-97 Full-Text PDF Regulation of renal tubular cell apoptosis and proliferation after ischemic injury to a solitary kidneyThe Journal of Laboratory and Clinical MedicineVol. 138Issue 5PreviewThe time course and regulation of apoptosis and cellular regeneration after 30 minutes of acute ischemic injury to a single kidney was elucidated in rats at five time points over 20 weeks. The fraction of apoptotic cells was most prominent at 1 day after the insult in the distal tubule (8% ± 4% vs 0% ± 0%, acute renal failure [ARF] vs sham, respectively) and was still elevated at 7 days (2% ± 2% vs 0% ± 0%). At that time, the whole kidney mRNA expression of the apoptosis inhibitory genes bcl-xL and bcl-2, as well as that of the apoptosis promotor bax, was significantly reduced. Full-Text PDF Red blood cell status in alcoholic and non-alcoholic liver diseaseThe Journal of Laboratory and Clinical MedicineVol. 138Issue 5PreviewMacrocytosis is most commonly associated with vitamin B12 and folic acid deficiency, followed by alcoholism, liver disease, and other pathologic conditions. We studied the red cell and vitamin status in 423 consecutive patients with various liver diseases, including 31 with acute viral hepatitis (AVH), 105 with chronic hepatitis (CH), and 134 with alcoholic liver disease (ALD), who consisted of 84 with non-cirrhotic alcoholic liver disease (NCALD) and 50 with alcoholic liver cirrhosis (ALC), 60 with non-alcoholic liver cirrhosis (NALC), and 93 with hepatocellular carcinoma (HCC). Full-Text PDF Identification and functional assessment of endothelial P1H12The Journal of Laboratory and Clinical MedicineVol. 138Issue 5PreviewMonoclonal antibody P1H12 recognizes circulating endothelial cells and endothelia of all sizes of blood vessels. To identify the protein recognized by P1H12, we expressed a cDNA library in CHO cells and sequenced the cDNA from positive cells. The P1H12 sequence was identical, except at several bases, to that reported for melanoma cell surface antigen MUC18/CD146. Aggregation assays demonstrated that CD146 mediates Ca++-independent homotypic endothelial cell adhesion. P1H12 mAb abrogated interactions between human microvascular endothelial cells (HMVECs) but not between human umbilical vein endothelial cells (HUVECs). Full-Text PDF
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