Primary cysts and tumors of the mediastinum

A retrospective analysis was performed on 230 patients with primary cysts and tumors of the mediastinum seen at our institution from January 1944 to April 1989. We divided these patients into two groups. Group 1 was seen before 1970 and group 2 was seen from January 1970 to April 1989. There was a significant increase in the prevalence of malignancy in group 2 (47.2% versus 17.1%; p less than 0.0001) due to an increase in the number of lymphomas (22.6% versus 3.5%; p less than 0.001) and malignant neurogenic tumors (6.8% versus 1.1%; p = 0.0528). There was a significant increase in the number of malignant tumors in the anterior (59.5% versus 30.9%; p = 0.0022) and paravertebral (28.5% versus 2.8%; p = 0.0027) compartments in group 2. More patients with these tumors were symptomatic in group 2 (63.6% versus 5%; p = 0.0422). There was an increase of ancillary diagnostic studies performed to evaluate these tumors (76.0% versus 34.5%; p = 0.0422). Logistic regression analysis identified date of presentation (p less than 0.005), symptoms (p less than 0.01), size (p less than 0.005), and the anterior mediastinal compartment (p less than 0.005) as preoperative predictors of malignancy. The surgical approach to these tumors included more median sternotomy (30.1% versus 10.7%; p = 0.0008), anterior mediastinotomy, and cervical mediastinoscopy in group 2 (1.1% versus 17.5%; p = 0.0002). Long-term results support surgical resection in benign lesions and an aggressive multimodality approach to malignant lesions.

[Acute retroviral syndrome]

A 37 year old male developed fever for 20 days, along with headache, anorexia, malaise, sweating, pharyngitis, lymphadenopathy and splenomegaly. At this stage, Ag p24 was positive and anti HIV was negative. The patient recovered fully but 6 months later positive HIV titers were demonstrated by immunofluorescence and Western-blot. A retrospective diagnosis of acute retroviral syndrome was made. The difficult differential diagnosis with infectious mononucleosis, cytomegalovirus, measles, rubella, toxoplasmosis and influenza is discussed. Thus, anti HIV antigenemia should be investigated in any patient with a mononucleosis like syndrome belonging in a high risk group for AIDS, even if Paul-Bunnell-Davidson or IgG anti VCA-EB reactions are positive.

Histoplasmosis duboisii (African histoplasmosis). An African case reported from Chile with ultrastructural study

A case of histoplasmosis duboisii in a 30 year-old engineer is presented. The diagnosis was made with the help of light microscopy, electron microscopy and cultures. Although diagnosed in Chile, the patient probably acquired the disease in the endemic African area, more precisely in the Ivory Coast. Differential diagnosis between Histoplasma capsulatum var. capsulatum and Histoplasma capsulatum var. duboisii is based primarily on the larger in-vivo yeast form size of the latter. Electron microscopy study, the first done on the duboisii variety of Histoplasma capsulatum in human material to our knowledge, was not essential for this purpose. Differential diagnosis between Histoplasma capsulatum var. duboisii and Blastomyces dermatitidis is based on morphological tissue changes and mycologic characteristics. Once more, a case of an "exotic" or geographically restricted disease is detected far from its endemic area, thanks to easier means of transportation. Earth is a shrinking planet.

Risk assessment in urgent/emergent coronary artery surgery

A statistical model has been developed to allow for prediction of individual patient prognosis following urgent/emergent coronary artery bypass grafting (CABG). None of the models previously described for use in coronary artery surgery has been tested with a prospective patient series that confirms the true predictive capacity of the model. Ideally, the predictive ability of such models should be validated with prospective trials. To examine the feasibility of statistical modeling in this clinical context, a computerized model based on the theorem of Bayes was developed to predict operative mortality for urgent coronary artery surgery. The presence or absence of 20 risk factors was determined for each of 405 consecutive patients undergoing urgent coronary artery surgery from January 1984 to January 1989. The first 100 patients were used to develop a database for the model, which was then used to prospectively evaluate the remaining 305 patients. There was good agreement between predicted and observed results. Models of this kind are particularly advantageous because of the ability to (1) accommodate multiple risk factors, (2) become tailored to a specific practice, and (3) determine individual rather than group prognosis. Validation with a prospective trial confirms the practical utility of this approach. This model has reliably predicted the risk associated with urgent coronary artery surgery and may provide important clinical information for the management of patients being evaluated for urgent revascularization.

True emergency coronary artery bypass surgery

Previous reports of emergency coronary artery bypass grafting often included cases that were not true surgical emergencies, thereby creating inappropriately favorable results. To accurately investigate this important subgroup of patients, we analyzed our recent experience with truly emergent coronary artery bypass grafting. From January 1984 to January 1989, 117 patients underwent true emergency bypass grafting for acute refractory coronary artery ischemia. Clinical deterioration was associated with failure of percutaneous angioplasty in 37 patients and instability during diagnostic catheterization in 13 patients. Refractory ischemia developed in the remaining patients while on the ward or in the intensive care unit. All operations were performed within four hours of surgical consultation, most within one hour. Overall in-hospital operative mortality was 14.5% (17/117), and 76.5% of deaths (13/17) were due to cardiac-related causes. Major morbidity occurred in 35.9% (42/117). Univariate analysis isolated ejection fraction, extent of coronary artery disease, previous myocardial infarction, hypertension, need for inotropic support, use of an intraaortic balloon pump, and cardiopulmonary resuscitation as risk factors for operative mortality. Stepwise multivariate analysis confirmed that previous myocardial infarction, hypertension, cardiopulmonary resuscitation, and reoperation were independently significant risk factors. Age, sex, diabetes, left main disease, and peripheral vascular disease had no significant impact on the prognosis. The 4% operative mortality (2/50) for patients taken directly to the operating room from the catheterization suite was significantly lower than the 22.4% mortality (15/67) associated with emergencies arising on the ward or intensive care unit (p less than 0.01). A logistic risk equation developed from this population accurately modeled operative mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Three-dimensional image reconstruction for planning of a complex cardiovascular procedure

A rare left subclavian artery aneurysm associated with a congenital arch anomaly was difficult to visualize using standard radiographic techniques. Three-dimensional computer imaging produced a clear depiction of this unusual anatomy and simplified the preoperative planning.

Thoracic irradiation in Hodgkin's disease: disease control and long-term complications

A total of 590 patients with Stage IA-IIIB Hodgkin's disease received mantle irradiation at the Joint Center for Radiation Therapy between April 1969 and December 1984 as part of their initial treatment. Recurrence patterns as well as pulmonary, cardiac and thyroid complications were analyzed. Pulmonary recurrence was more frequently seen in patients with large mediastinal adenopathy (LMA); 11% of patients with LMA recurred in the lung in contrast to 3.1% with small or no mediastinal disease, p = 0.003. Hilar involvement, when corrected for size of mediastinal involvement, was not predictive of lung relapse. Patients with LMA also had a high rate of nodal relapse above the diaphragm (40%) following radiation therapy (RT) alone as compared to similarly treated patients with small or no mediastinal adenopathy (6.5%), p less than 0.0001. This risk of nodal recurrence was greatly reduced (4.7%) for LMA patients receiving combined radiation therapy and chemotherapy (CMT), p less than 0.0001. Sixty-seven patients (11%) with hilar or large mediastinal involvement received prophylactic, low dose, whole lung irradiation. No decrease in the frequency of lung recurrence was seen with the use of whole lung irradiation. Radiation pneumonitis was seen in 3% of patients receiving radiation therapy alone. In contrast, the use of whole lung irradiation was associated with a 15% risk of pneumonitis, p = 0.006. The risk of pneumonitis was also significantly increased with the use of chemotherapy (11%), p = 0.0001. Cardiac complications were uncommon with pericarditis being the most common complication (2.2%). Thyroid dysfunction was seen in 25% of patients and appeared to be age-related. These data suggest that the long-term complications of mantle irradiation are uncommon with the use of modern radiotherapeutic techniques. The use of prophylactic whole lung irradiation is no longer recommended since its use did not reduce pulmonary relapse but did increase the risk of pneumonitis. Chemotherapy is also associated with an increased risk of pneumonitis, however, its use in patients with large mediastinal adenopathy appears justified.

Migration in a small semiperiphery: the movement of Puerto Ricans and Dominicans

"This article argues that the semiperipheral development of Puerto Rico since around 1975 has led to the creation of a relative labor surplus in the formal sectors of the economy while at the same time increasing the demand for cheap labor in the informal service sector. Thus, Puerto Ricans leave their country in search of good jobs in the United States while Dominicans migrate to Puerto Rico and find work in the informal sector. The return migration of Puerto Ricans has also been significant, but is due to their strong national culture, rather than economic reasons. The article concludes that migration to and from Puerto Rico is of a semiperipheral type because it combines characteristics of migration previously described as 'migration from the periphery to the center' and 'migration within the periphery.' A precise definition of the semiperipheral characteristics of Puerto Rico is given."

Substance misuse and HIV/AIDS risks among delinquents: a prevention challenge

In the United States, there is growing concern that adolescents are at increasing risk for HIV-1 infection due to recreational substance use and sexual activity. Self-report questionnaires from a sample of 224 incarcerated delinquents quantified associations between drug use, sex, and other behaviors which risk HIV-1 infection. High rates of substance use and HIV-risking behaviors were found. Significant correlations between levels of substance use and both behavioral and attitudinal barriers to HIV/AIDS prevention programming were observed. This evidence and other subgroup differences in denial of vulnerability and in practice of preventive behaviors indicate the need for different approaches to prevention. An integrated HIV/AIDS and substance misuse prevention program is discussed as a viable alternative to the usual knowledge-enhancing programs.

Protection by superoxide dismutase from myocardial dysfunction and attenuation of vasodilator reserve after coronary occlusion and reperfusion in dog

Previous studies indicate impairment of coronary arterial ring relaxation and loss of coronary vasodilator reserve after coronary artery occlusion and reperfusion. These changes are mediated in part through loss of endothelium-derived relaxing factor (EDRF) and/or myocardial neutrophil accumulation. To examine if superoxide dismutase (SOD), a scavenger of superoxide radicals, would modify the diminished coronary vasodilator reserve after temporary coronary occlusion in the intact animal, open-chest mongrel dogs were subjected to 1 hour of circumflex (Cx) coronary artery occlusion followed by 1 hour of reperfusion and treated with saline or SOD. Before Cx occlusion, coronary blood flow increased, and vascular resistance decreased (both p less than 0.01) in response to EDRF-dependent vasodilator acetylcholine as well as EDRF-independent vasodilator nitroglycerin. After Cx reperfusion, resting Cx coronary blood flow and vascular resistance were similar to the preocclusion values. In the saline-treated animals, there was evidence of myocardial dysfunction, which was measured by segmental shortening (-6 +/- 2% vs. 10 +/- 2%). Furthermore, increase in Cx coronary blood flow and reduction in vascular resistance in response to both vasodilators were significantly (p less than 0.01) impaired; these occurrences suggested loss of coronary vasodilator reserve. Myocardial histology showed extensive capillary plugging by neutrophils in the Cx-supplied myocardium. Myocardial myeloperoxidase activity, an index of neutrophil infiltration, was also increased in the Cx compared with the left anterior descending coronary artery region (p less than 0.02). Treatment of dogs with SOD, started at the end of Cx occlusion and continued during reperfusion, exerted significant (p less than 0.01) protective effect against reperfusion-induced attenuation of coronary vasodilator reserve in response to both acetylcholine and nitroglycerin. Loss of myocardial function (segmental shortening 5 +/- 1% vs. 10 +/- 1%) was less than in the saline-treated animals (p less than 0.01). Cx region-myocardial neutrophil accumulation and myeloperoxidase activity were also less (p less than 0.02) in the SOD-treated than in the saline-treated dogs. These observations suggest that coronary reperfusion impairs coronary vasodilator reserve in intact dogs. This impairment can be modified by treatment of animals with SOD before reperfusion. Capillary plugging by neutrophils may contribute to the altered coronary vasodilator reserve observed in the immediate postreperfusion period, and SOD modifies this reperfusion-induced impairment.

Use of artificial intelligence for the preoperative diagnosis of pulmonary lesions

The relatively new field of artificial intelligence has spawned a variety of techniques associated with computer-assisted diagnosis. These techniques have been applied to the diagnosis of pulmonary lesions, but previous reports have focused on medical rather than surgical populations and the results have been evaluated using only retrospective patient surveys. We used a Bayesian algorithm to develop a diagnostic computer model for prospectively evaluating patients undergoing thoracotomy for suspected pulmonary malignancy. Patients who had a preoperative diagnosis were not included. Preoperative clinical and radiographic parameters for 100 consecutive patients were prospectively entered into the diagnostic model, which then categorized the lesion as benign or malignant. The computer predictions agreed with the final histological diagnosis in 95 of the 100 patients. The sensitivity was 96% and the specificity was 89% for this prospective series. These results indicate that the computer-assisted diagnosis of pulmonary lesions may have a role in this clinical setting.

Regional localization of human ecto-5' nucleotidase to chromosome 6q14-q21

Human and mouse hybrids that contain fragments of human chromosome 6 as translocations were analysed for expression of ecto-5' nucleotidase enzymic activity measured by the conversion of AMP to adenosine and for antigenicity recognized by a monoclonal antibody specific for the human isozyme. Both methods allow a regional assignment of ecto-5'nucleotidase to 6q14-q21.

Summary of complementation groups of UV-sensitive CHO cell mutants isolated by large-scale screening

A summary is given for the lineage and complementation group assignments of 153 UV-sensitive mutants of the CHO AA8 cell line. The distribution of mutants among six complementation groups was highly non-random, with the great majority of the isolates belonging to groups 1 and 2. This asymmetry is consistent with the known hemizygosity of these two linked loci in CHO cells. The relative numbers of mutants induced in group 2 was found to depend greatly on the type of mutagen used. Mutagenesis with UV radiation, ethyl methanesulfonate (EMS), N-methyl-N'-nitro-N-nitrosoguanidine and 7-bromomethylbenz[a]anthracene produced high frequencies of group 2 mutants. In contrast, ICR170 and ICR191, which are thought to produce mostly frameshift mutations, yielded very few mutants in group 2. These results are of particular importance in light of the recent finding that the human ERCC2 gene, which corrects group 2 mutants, has very strong homology with the yeast gene RAD3. RAD3 is an essential gene for viability in yeast, and the low recovery of group 2 mutants using the frameshift agents strongly suggests that frameshift mutations tend to be lethal in the hamster ERCC2 locus. Several mutagen-sensitive double mutants were isolated in two-step selections from EMS-, mitomycin C- or UV-sensitive parental cells, including the line UVU1, the first mammalian line with two mutations that affect UV sensitivity. The first mutation inactivated excision repair, and the second mutation appears to have affected some other recovery process. UVU1 should be useful for studying recovery processes that are separate from nucleotide excision repair.

The reservoir for HIV-1 in human peripheral blood is a T cell that maintains expression of CD4

Human immunodeficiency virus type 1 (HIV-1) selectively infects cells expressing the CD4 molecule, resulting in substantial quantitative and qualitative defects in CD4+ T lymphocyte function in patients with acquired immunodeficiency syndrome (AIDS). However, only a very small number of cells in the peripheral blood of HIV-1-infected individuals are expressing virus at any given time. Previous studies have demonstrated that in vitro infection of CD4+ T cells with HIV-1 results in downregulation of CD4 expression such that CD4 protein is no longer detectable on the surface of the infected cells. In the present study, highly purified subpopulations of peripheral blood mononuclear cells (PBMCs) from AIDS patients were obtained and purified by fluorescence-automated cell sorting. They were examined with the methodologies of virus isolation by limiting dilution analysis, in situ hybridization, immunofluorescence, and gene amplification. Within PBMCs, HIV-1 was expressed in vivo predominantly in the T cell subpopulation which, in contrast to the in vitro observations, continued to express CD4. The precursor frequency of these HIV-1-expressing cells was about 1/1000 CD4+ T cells. The CD4+ T cell population contained HIV-1 DNA in all HIV-1-infected individuals studied and the frequency in AIDS patients was at least 1/100 cells. This high level of infection may be the primary cause for the progressive decline in number and function of CD4+ T cells in patients with AIDS.

The illusory home, or the 24 percent fallacy

Although many elderly people live for years in nursing homes, death certificates routinely obliterate nursing home residence. Data gathered from records of one proprietary nursing home show that of 128 residents, from 45 percent to 66 percent could be classified as "permanent," depending on the definition. Nevertheless, the death certificates for those 128 residents list the nursing home as the residence for only 24 percent. This article explores that bias.

Effect of melatonin on jet lag after long haul flights

OBJECTIVE

To determine whether doses of the pineal hormone melatonin alleviate jet lag.

DESIGN

Double blind, placebo controlled crossover trial.

SETTING

Long haul return flights from Auckland, New Zealand, to London and back.

SUBJECTS

Twenty volunteers with experience of transcontinental flights (eight women and 12 men aged 28 to 68).

INTERVENTIONS

Melatonin (or placebo) 5 mg three days before flight, during flight, and once a day for three days after arrival.

END POINT

Symptoms of jet lag.

MEASUREMENTS AND MAIN RESULTS

Visual analogue scale for feelings of jet lag and tiredness; profile of moods states questionnaire for vigour-activity and fatigue-inertia; and retrospective ratings 10 days after arrival of sleep pattern, energy, and daytime tiredness. Feelings of jet lag were less for subjects taking melatonin (mean score 2.15 v 3.4); these subjects took fewer days than the placebo group to establish a normal sleep pattern (2.85 v 4.15), to not feel tired during the day (3.0 v 4.6), and to reach normal energy levels (3.25 v 4.7). Results for fatigue-inertia and vigour-activity were similar. For all subjects jet lag was more severe on the return (westward) than the outward (eastward) journey.

CONCLUSIONS

Melatonin can alleviate jet lag and tiredness after long haul flights.

Cryopreservation of innervation, endothelial and vascular smooth muscle function of a rabbit muscular and resistance artery

The extent of preservation of endothelial, neurogenic and vascular function following frozen storage was studied using the rabbit central ear artery and a resistance artery branch. Fresh and frozen-stored artery segments were placed in tissue baths containing a physiological buffer solution and attached to a wire myograph apparatus for measurement of isometric force. Responses to cumulative additions of norepinephrine, histamine, acetylcholine and sodium nitroprusside were compared between fresh arteries and adjacent segments that had been stored frozen for 2-8 days at -70 degrees C. Responses to transmural nerve stimulation were measured in central ear artery segments that were fresh or stored frozen for 13-26 days. Large and small artery segments were frozen in ampules containing newborn calf serum and 1.8 M dimethylsulfoxide used as a cryoprotective agent. Following frozen storage, the vascular sensitivity of large and resistance arteries to norepinephrine and histamine were unaltered although maximal contractile responses were significantly reduced. Agonist affinity (KA values) to norepinephrine was also unchanged following frozen storage of large artery segments. Constrictor responses to varied frequencies of transmural nerve stimulation were similar between fresh and frozen-stored large arteries, suggesting that adrenergic nerve function is well preserved. In resistance arteries, vascular sensitivity and maximal relaxation to acetylcholine and sodium nitroprusside were unchanged. Similarly, relaxation of large arteries to sodium nitroprusside was well preserved. Although vascular sensitivity to acetylcholine was reduced in large arteries following frozen storage, much of the endothelial function was still preserved as indicated by only a 10% decrease in maximal relaxation.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction in coronary vasodilator reserve following coronary occlusion and reperfusion in anesthetized dog: role of endothelium-derived relaxing factor, myocardial neutrophil infiltration and prostaglandins

To examine the effects of acute myocardial ischemia and reperfusion on regional coronary vasodilator (or flow) reserve, peak reactive hyperemic blood flow following a 10 s occlusion was obtained in dogs subjected to circumflex (Cx) coronary artery occlusion for 1 h followed by reperfusion for 1 h. Acute myocardial ischemia resulting from Cx artery occlusion-reperfusion caused an attenuation in peak reactive hyperemic Cx flow (mean +/- S.E., from 215 +/- 29% to 87 +/- 17%, P less than or equal to 0.001). Acetylcholine-induced increase in Cx flow was also significantly (P less than or equal to 0.01) attenuated following Cx occlusion-reperfusion. These alterations were not observed in the left anterior descending (LAD) coronary artery, which was not subjected to occlusion. Pre-treatment of four dogs with indomethacin inhibited prostaglandin release (P less than or equal to 0.01), but did not affect peak reactive hyperemic coronary flow or acetylcholine-induced increase in coronary flow before or after occlusion-reperfusion. Histopathology revealed extensive myocardial neutrophil infiltration in the Cx-supplied region compared to the LAD-supplied region. Myocardial myeloperoxidase activity, an index of neutrophil infiltration, was also increased in the Cx compared to the LAD region (P less than or equal to 0.02). Myocardial neutrophil accumulation and myeloperoxidase activity were similar in the control and indomethacin-treated animals. These observations suggest that acute myocardial ischemia resulting from coronary artery occlusion-reperfusion impairs coronary vasodilator reserve in anesthetized dogs. This impairment, which was not modified by prostaglandin inhibition, may be related to the loss of endothelium-derived relaxing factor and/or decreased microvascular cross-sectional area resulting from capillary plugging by neutrophils.

The effects of acute sleep deprivation during residency training

Verbal and symbol concentration, learning, problem solving, clear thinking, manual skills, and memory were tested in 42 surgical residents to assess the effects of acute sleep deprivation on specific neuropsychological parameters. A series of eight neuropsychological tests--digit symbols, digit vigilance, story memory, trail making, PASAT, Raven matrices, delayed story, and pegboard--and a questionnaire on mood states were completed by the residents both when fatigued (less than 4 hours of sleep: mean, 2.0 +/- 1.5 hours) and when rested (more than 4 hours of sleep: mean, 6.5 +/- 1.0 hours), with at least 7 days between tests. In order to eliminate the effects of learning from the first test series, randomization of residents was performed so that one half were first evaluated when rested and one half when fatigued. ANOVA, multiple regression analysis, and the Student t test were used to assess differences. In the acute sleep-deprived state, residents were less vigorous and more fatigued, depressed, tense, confused, and angry (p less than 0.05) than they were in rested state. Despite these changes in mood, however, the responses on all of the functional tests were no different statistically in those who were rested and those who were fatigued (even in those with less than 2 hours' sleep). We conclude that acute sleep deprivation of less than 4 hours alters mood state but does not change performance in test situations in which concentration, clear thinking, and problem solving are important.

Synergistic effects of LTC4 and TxA2 on coronary flow and myocardial function

Accumulation of leukocytes and platelets in the injured myocardium may influence coronary arteriolar resistance via release of peptidoleukotrienes and thromboxane A2 (TxA2). Although leukotriene C4 (LTC4) and TxA2 individually reduce coronary blood flow, the effects of their simultaneous administration are not known. Accordingly, the combined effects of intracoronary administration of synthetic LTC4 and thromboxane "mimic" U 46619 on coronary blood flow in patent and severely narrowed coronary arteries and myocardial segmental function were examined in eight anesthetized dogs. Administration of LTC4 and U 46619 (0.3-3 micrograms) showed concentration-dependent reductions in coronary blood flow and myocardial segment shortening. When these eicosanoids (3 micrograms each) were administered in close sequence, coronary blood flow decreased 33% in the patent artery and 47% in the narrowed artery. This reduction in coronary blood flow in the narrowed coronary artery produced a 26% decrease in myocardial segment shortening. Reductions in narrowed coronary artery blood flow and myocardial segment shortening were greater than the sum of changes caused by LTC4 and U 46619 administered separately (P less than 0.05). The histopathology of the narrowed coronary artery revealed endothelial disruption at the site of occlusion and an in vivo thrombus just distal to the site of occlusion. These data suggest marked synergism between the actions of LTC4 and TxA2, which may be released locally at the site of coronary thrombus, on blood flow in a severely narrowed coronary artery, and on segmental function in the region supplied by this vessel.