Human T lymphotropic virus type III infection of human alveolar macrophages

The human T-cell lymphotropic virus type III (HTLV-III) is the etiologic agent of the acquired immunodeficiency syndrome (AIDS) and preferentially infects T4 lymphocytes. Other cell types, notably B lymphocytes and other nonlymphoid cells, also have been reported to be infected in vitro by HTLV-III. We now report on the susceptibility of human pulmonary macrophages to infection with HTLV-III in vitro. Alveolar macrophages infected with HTLV-III produced low levels of virus that could be transferred to allogeneic human peripheral blood mononuclear leukocytes as long as 2 weeks after initiation of infection. Unlike HTLV-III infection of T lymphocytes, macrophages appeared more resistant to viral-mediated cytopathic effects. Primary cultures of pulmonary macrophages from two of four patients with AIDS spontaneously produced low levels of virus detected as precipitable reverse transcriptase activity, suggesting that these cells were infected in vivo. Because tissue macrophages are long-lived cells, they may act as a reservoir of HTLV-III, capable of transmitting the virus to other susceptible cells such as T lymphocytes, causing periodic low-level viremia. Macrophage infection with HTLV-III may be one mechanism for the establishment of viral persistence in infected hosts.

Endobronchial involvement with non-Hodgkin's lymphoma. A clinical-radiologic analysis

Based on experience with three cases of endobronchial non-Hodgkin's lymphoma and a review of cases previously reported, two patterns of lymphomatous involvement of airways are described. The Type 1 pattern is characterized by diffuse submucosal infiltrates occurring in the presence of intra- and extrathoracic lymphoma. In Type 2 cases, central airways are involved by a solitary mass in the absence of clinically apparent systemic lymphoma. The clinical-radiologic picture is characterized by signs of pneumonitis in Type 1 cases, while in Type 2 cases, signs of airway obstruction uniformly occur.

Platelet MAO concentration and molecular activity: II. Comparison of normal and schizophrenic populations

Platelet monoamine oxidase (MAO B) in 59 normal and 57 RDC-diagnosed medicated and unmedicated schizophrenic subjects was analyzed for whole platelet and extracted activities, specific concentration, and molecular activity. A novel radioimmunoassay using a monoclonal antibody elicited to human platelet MAO was used. Female schizophrenics showed no differences from female normals in MAO measures; however, these data could not be clearly evaluated because of confounding effects of age and drugs. Male schizophrenics treated with neuroleptics expressed significantly reduced whole platelet MAO activity, compared to untreated male patients. Compared with normal males, male schizophrenics showed significantly lowered molecular activities, along with elevated specific concentrations, which did not appear to be explained solely by drug usage. Additional mechanisms explaining the diminished molecular activity in male schizophrenics may be the presence of an endogenous irreversible inhibitor or a genetically determined, possibly structural, variant of MAO B.

An acidic lymphokine distinct from interferon-gamma inhibits the replication of herpes simplex virus in human pulmonary macrophages

Supernatants from concanavalin A-stimulated human peripheral blood mononuclear cells were fractionated by gel filtration and isoelectric focusing. A fraction with an isoelectric point of 2.2-3.3 containing macrophage migration inhibition factor activity inhibited the replication of herpes simplex virus type 1 in human pulmonary macrophages and U937 cells. This fraction did not inhibit the replication of herpes simplex virus in human fibroblasts. Moreover, the ability of this lymphokine fraction to inhibit viral growth in macrophages was not neutralized by antibody against interferon-gamma. These findings identify a macrophage specific antiviral lymphokine which is distinct biochemically and immunologically from interferon-gamma.

Platelet MAO concentration and molecular activity: I. New methods using an MAO B-specific monoclonal antibody in a radioimmunoassay

New methods for determination of specific concentration and molecular activity of monoamine oxidase (MAO) in platelets are described and evaluated in parallel with specific activity measures, performed in whole platelets and platelet extracts. Platelet MAO specific concentration is determined in platelet extracts by a radioimmunoassay, using a monoclonal antibody that recognizes human MAO B, the form that occurs in platelets, but not MAO A. All four platelet MAO measures are found to be reliable and stable, and thus are suitable for long-term comparisons of normal and clinical populations, such as those reported in Part II of this report. The new measures of enzyme concentration and molecular activity make available important information about the state of MAO B molecules in a given individual that reflects the genetic expression and control of the enzyme.

Solitary nodular sarcoidosis

Three patients, each with a solitary lung nodule consisting of sarcoid tissue, are described. With the exception of one case where a submandibular lymph node was palpable, clinical and pathological involvement was limited to the thorax and the prognosis was highly favourable. In spite of atypical features, the absence of other causes of granulomatous inflammation suggests that these patients had sarcoidosis. What factors account for limited granulomatous reaction in this form of sarcoidosis are unknown. Previous use of corticosteroids and an age of over 40 years are two possible causes suggested by these cases.

Distinct monoamine oxidase A and B populations in primate brain

Monoclonal antibodies specific for monoamine oxidase (MAO) A and MAO B, respectively, were used to localize these enzymes in primate brain. The reagents recognized different populations of neurons: those that recognized MAO A were located in cell groups containing catecholamines, including the substantia nigra, nucleus locus coeruleus, nucleus subcoeruleus, and the periventricular region of the hypothalamus, whereas those that recognized MAO B were observed in serotonin regions, including the nucleus raphe dorsalis and nucleus centralis superior. These data illustrate the physiological independence of MAO A and B and show that neurons may be specialized for their degradative as well as their synthetic functions.

A model of a thalamic neuron

We modify our recent three equilibrium-point model of neuronal bursting by a means of a small deformation of the nullclines in the x-y phase plane to give a model that can have as many as five equilibrium points. In this model the middle stable equilibrium point (e.p.) is separated from the outer stable and unstable e.ps by two saddle points. If the system is started at rest at the middle stable e.p. it has the following complex properties: A short suprathreshold current pulse switches the model from a silent state to a bursting state, or to give a single burst, depending on the choice of parameters. A subthreshold depolarizing current step gives a passive response at rest, but if the model is either constantly hyperpolarized or constantly depolarized, then the same current step gives different active responses. At a hyperpolarized level this consists of a burst response that shows refractoriness. At a depolarized level it consists of tonic firing with a linear frequency--current relationship. Hyperpolarization from rest is followed by post-inhibitory rebound. The model responds in a unique and characteristic way to an applied current ramp. These properties are very similar to those that have been recently recorded intracellularly from neurons in the mammalian thalamus. In the x-y phase plane our models of the repetitively firing neuron, the bursting neuron and the thalamic neuron form a progression of models in which the y nullcline in the subthreshold region is deformed once to give the burst neuron model, and a second time to give the thalamic neuron model. Each deformation can be interpreted as corresponding to the inclusion of a slow inward current in the model. As these currents are included so the associated firing properties increase in complexity.

CT findings in pleural aspergillosis

Two patients who underwent pulmonary resections for lung cancer developed delayed pleural abnormalities. In each instance CT confirmed the presence of pleural thickening, nodularity, and intrapleural masses proven to represent intrapleural aspergillomas.

Cardiopulmonary function following post-cardiac surgical mediastinitis

Eleven survivors of bacterial mediastinitis, which followed cardiac surgery through a median sternotomy approach, underwent noninvasive cardiopulmonary evaluation to determine whether clinically apparent mediastinal fibrosis had developed. Compared to preoperative values, forced vital capacity was reduced by 9.75 percent of predicted; the greatest reduction occurred in those patients with Gram-negative mediastinitis. In one patient, an abnormal jugular venous wave form and apex cardiogram were consistent with constrictive cardiac physiology, but this was not associated with an abnormal echocardiogram or impaired functional status. In this small series, no serious abnormalities in cardiopulmonary function were detected which could be attributed to prior mediastinal infection.

A model of neuronal bursting using three coupled first order differential equations

We describe a modification to our recent model of the action potential which introduces two additional equilibrium points. By using stability analysis we show that one of these equilibrium points is a saddle point from which there are two separatrices which divide the phase plane into two regions. In one region all phase paths approach a limit cycle and in the other all phase paths approach a stable equilibrium point. A consequence of this is that a short depolarizing current pulse will change an initially silent model neuron into one that fires repetitively. Addition of a third equation limits this firing to either an isolated burst or a depolarizing afterpotential. When steady depolarizing current was applied to this model it resulted in periodic bursting. The equations, which were initially developed to explain isolated triggered bursts, therefore provide one of the simplest models of the more general phenomenon of oscillatory burst discharge.

Radiation sterilization and the wear rate of polyethylene

The resistance to sliding wear was measured in bovine serum for two polyethylenes with molecular weights of about 10(5) and 10(6) that had been irradiated in air and nitrogen with gamma-ray dosages up to 20 Mrad. Molecular weight measurements were performed after irradiation as well. Wear generally increased with dosage and contact stress, becoming measurable in many cases only after a critical dose (or stress) was exceeded. The most significant effect noted was that the irradiation changed the pressure dependence of the wear rate. Thus, whether or not a sterilizing (or resterilizing) dose will measurably increase the wear depends on the contact stress and, therefore, on the specific application. The increase in wear rate appeared to be due to a combination of scission and oxidation, suggesting the practical advisability of radiation sterilization under an inert atmosphere, as confirmed by comparative measurements at the higher dosages.

Architectural changes in the proximal femur following prosthetic insertion: preliminary observations of an animal model

A study was made of the changes occurring in the proximal femur following unilateral total hip replacement in fourteen sheep. Implants were observed 0-12 months post-operatively. Contralateral implants inserted at sacrifice served as controls. The paired specimens were cut into five transverse sections and stereologically analyzed. The following phenomena were seen during the post-operative year: (a) calcar resorption; (b) encapsulation of the prosthetic cement in fibrous sheath; (c) interruption of the trabecular network between the cement-stem system and the cortex; (d) increase in the cross-sectional moment of inertia of the cortical shell. These changes form a consistent pattern of biological responses to the implant, the details of which are important because they suggest failure mechanisms and demonstrate the inadequacy of simple analytical models based on static pictures of the bone-implant composite structure. Failure modes may depend on the initial degree of bone-cement interdigitation. Concentric layers of fibrous tissue surrounded by layers of dense bone were formed where interdigitation was not extensive. Where interdigitation was maximal, a band of bony resorption separated the cement-bone complex from the endosteal trabecular bone. Increased levels of bone-cement interdigitation would not appear to influence the ultimate outcome, but, rather, only the mode of failure of the prosthetic attachment.

Electrotonic coupling and afterdischarges in the Light Green Cells: a comparison with two other cerebral ganglia neurosecretory cell types in the pond snail. Lymnaea stagnalis

Electrotonic coupling occurs between the growth hormone-producing Light Green Cells on the same but not the opposite side of the brain of Lymnaea. Long duration inhibitory post synaptic potentials occur spontaneously or can be evoked by nerve or connective stimulation. Afterdischarges, lasting for up to 1 min, are evoked by brief stimulation of the median lip nerves. Activity is confined to cells ipsilateral to the nerve being stimulated. The electrical properties of the Light Green Cells are compared with those of the Caudodorsal Cells and Canopy Cells.

Corrosion of titanium/cobalt-chromium alloy couples

Because of the increasing use of dissimilar metal combinations in the human body, we undertook an in vitro study to determine the compatibility and tendency to accelerate crevice corrosion of galvanic couples of cobalt-chromium alloy with either titanium, titanium alloy, or stainless steel. We employed an electrochemical open-circuit potential measurement test and a potentiostatic passive film-corrosion measurement test. The results demonstrated that the chromium alloy/stainless-steel couple was unstable. The cobalt-chromium alloy/titanium alloy couple was stable.

CLINICAL RELEVANCE

Cobalt-chromium alloys should not be used in combination with stainless steel but may be used in combination with titanium alloy. All usage of metal couples should be approached with the utmost caution.

Mediastinitis after cardiovascular surgery

Postoperative mediastinitis complicated 21 (3.4%) of 616 median sternotomy procedures at Beth Israel Hospital (Boston, Mass.) between 1975 and 1979. These cases were analyzed by means of a case control study to identify host and operative risk factors and to characterize the clinical features of mediastinitis. Eighteen patients with mediastinitis (86%) had serious underlying noncardiac diseases, as compared with 14 (33%) of 42 noninfected controls (P = .001). Reoperation was positively associated with infection (P = .03). All patients had abnormal sternal wounds and fever; sternal instability and mediastinal widening were unusual. Twelve patients (57%) were bacteremic. Twenty-four organisms were recovered from the 21 patients with mediastinitis; 13 of the isolates were gram-positive, and 11 were gram-negative. Infections due to gram-negative bacteria appeared earlier and were more likely to be bacteremic (70%). All gram-negative isolates and five of six isolates of Staphylococcus epidermidis were resistant to the antimicrobial agent used perioperatively. Patients were treated with extensive debridement and appropriate antibiotics. The mortality rate was 24% (five of 21). Long-term complications in survivors were not seen.

Tranylcypromine lowers human platelet MAO B activity but not concentration

Monoamine oxidase content in extracts of human blood platelets was determined independently of MAO activity measurements with a recently developed monoclonal antibody against human platelet monoamine oxidase (MAO B) in a competitive radioimmunoassay. Administration of a single oral dose of the irreversible inhibitor tranylcypromine to normal human subjects resulted in a rapid and marked inhibition of platelet MAO catalytic activity within 1 day, followed by recovery of activity to normal levels within 2 weeks. In contrast, there was no change in the net concentration of MAO protein during this time. Since recovery of MAO B activity approximated the reported half-life of blood platelets, these results suggest that recovery of platelet MAO activity after tranylcypromine treatment is due to the replacement of old platelets by new ones which contain catalytically active MAO B.