Anatomy of the minor fissure: evaluation with thin-section CT

The minor fissure was studied with thin computed tomographic (CT) sections in 40 patients. It was absent in eight (20%) and seen in 32 (80%) patients; of these 32 the fissure was complete in seven (22%), incomplete in 23 (72%), and of indeterminate completeness in two (6%). Appearance of the minor fissure on CT scans can be categorized into two major configurations, which are determined by variation in contour of the middle lobe upper surface. The location of the highest point along this surface is either medial (type I configuration) or lateral (type II configuration). The lowest tributary of the vein draining the anterior segment of the upper lobe was seen in 75% of the patients. This vessel was a reliable landmark in delineating boundaries between upper and middle lobes, even when the fissure was radiologically incomplete or absent. In the authors' experience, familiarity with these configurations of the minor fissure has been useful in localization of a lesion in a lobe or determination of its possible extension beyond the fissure into the neighboring lobe.

Spontaneous regression of pulmonary metastases from renal cell carcinoma

One year after nephrectomy for renal cell carcinoma in a seventy-year-old man pulmonary nodules developed which proved to be metastases by needle biopsy. Chest radiographs thirteen and eighteen months later revealed complete spontaneous regression of the nodules without therapy.

Pleural effusions: pathogenesis, radiologic evaluation, and therapy

The imaging of pleural effusions by plain radiography, sonography, computed tomography (CT), and magnetic resonance imaging (MRI) has greatly facilitated the planning of both initial diagnostic thoracentesis and subsequent therapeutic management. The normal anatomy and physiology of the pleura, the pathogenesis of effusions, and the clinical criteria for classifying effusions are briefly summarized. The usefulness of each imaging modality is then discussed, particularly with regard to the problems of detecting small effusions, identifying loculation of fluid, distinguishing pleural from intraparenchymal disease, and assessing the extent to which a pleural process has become organized.

Differential survival of chaparral seedlings during the first summer drought after wildfire

Big Pod Ceanothus (Ceanothus megacarpus) is an obligate seeder after fire; Laurel Sumac (Rhus laurina) is primarily a resprouter after fire. Both species commonly occur together in mixed stands and are dominant members of the coastal chaparral of southern California. We compared the mean survival of post-fire seedlings of each species during the first summer drought after fire and found C. megacarpus to have a mean survival of 54% while R. laurina had a mean survival of only 0.1%. Rooting dephs were similar between species but predawn water potentials and leaf temperatures were higher for R. laurina seedlings. Leaf temperatures for R. laurina reached a mean value of 46.8° C on hot, summer days, about 5° C higher than seedlings of C. megacarpus. By the end of the first growing season, 92% of all C. megacarpus seedlings had suffered herbivory compared to only 17% of all R. laurina seedlings. Herbivory did not appear to be the immediate cause of seedling mortality. Transect data indicated that full recovery of prefire species composition and density at our study site was likely but the mode of recovery was different for the species examined. R. laurina recovered primarily by sprouting, C. megacarpus totally by seedling establishment and a third species, Adenostoma fasciculatum (chamise), by a combination of sprouting and seedling establishment. We attribute the higher mortality of R. laurina seedlings to the greater sensitivity of its tissue to water stress. It may be that differential survival of shrub seedlings and differential modes of reestablishment after fire play an important role in maintaining species diversity in the chaparral communities of coastal, southern California.

Fortified antibiotic ointment in bacterial keratitis

We conducted experiments to determine the effectiveness of fortified antibiotic ointment in the treatment of Pseudomonas keratitis in rabbits. We evaluated gentamicin ointment (3, 10, 20, and 40 mg/g), gentamicin solution (3 and 10 mg/ml), and placebo, each given every 30 minutes. We also examined the effectiveness of fortified ointment given in extended treatment intervals. In short-term trials, commercial-strength gentamicin solution (3 mg/ml) was therapeutically superior (P less than .001) to commercial-strength gentamicin ointment (3 mg/g) in reducing corneal bacterial colony counts. No significant difference in antimicrobial effect was noted between fortified gentamicin ointment and fortified gentamicin solution at 30-minute treatment intervals. Fortified gentamicin ointment reduced colony counts even at extended treatment intervals of up to four hours in a severe keratitis model.

False pulmonary artery aneurysm induced by Swan-Ganz catheter: diagnosis and embolotherapy

A false aneurysm that formed after injury by a Swan-Ganz catheter to the pulmonary artery in a patient on long-term anticoagulant therapy is reported. The lesion was demonstrated both by computed tomography and pulmonary angiography. The case is unique in that the patient was successfully treated with percutaneous transcatheter embolization.

Detection of bronchial abnormalities: comparison of CT and bronchoscopy

We evaluated the usefulness of CT as compared with both visual and pathologic findings from fiberoptic bronchoscopy (FOB) in detecting bronchial lesions in 100 consecutive patients undergoing both procedures. There was agreement between CT and visual FOB in 83% of cases and CT and pathologic FOB in 68%. In the malignant disease category CT detected bronchial abnormalities in 59% (27 of 46) as compared with 57% (26 of 46) by visual FOB; both agreed in 81% of the cases (37 of 46). On the basis of CT findings alone, we retrospectively divided the cases into those for which we expected FOB to have high diagnostic yield (peribronchial abnormalities, n = 49) and a low diagnostic yield (i.e., no bronchial abnormality, n = 51). For the malignant disease category, selection by CT findings resulted in successful diagnosis by FOB in 69% for the high yield group as compared with 29% for the low yield group. We conclude that CT has excellent correlation with visual and pathologic results of FOB in detecting bronchial abnormalities and that CT, when used as an initial screening test, can enhance the yield by allowing appropriate selection of patients.

Intrathoracic Kaposi sarcoma in AIDS patients: radiographic-pathologic correlation

The chest radiographs and postmortem pathologic findings in 24 patients with acquired immunodeficiency syndrome (AIDS) and autopsy-proved intrathoracic Kaposi sarcoma were reviewed. Premortem radiographic visualization of pulmonary lesions of Kaposi sarcoma depended on the extent of involvement and the presence of concomitant disease. In three patients (13%) the radiographs showed nodular opacities that corresponded in size and configuration to nodules seen at autopsy. In 21 patients (87%) the lesions were not radiographically identifiable, in some cases because they were obscured by infection. The positive and negative predictive values of four radiographic findings for intrathoracic Kaposi sarcoma were evaluated, using a control group of 14 AIDS patients without intrathoracic Kaposi sarcoma at autopsy. Findings with a high positive predictive value were parenchymal nodular and reticular opacities (100%), pleural effusions (89%), and hilar and/or mediastinal lymphadenopathy (92%). None of these findings is specific, but the presence of any one in a patient with AIDS should increase the possibility of intrathoracic involvement by Kaposi sarcoma.

Relationship between proteases and descemetocele formation in experimental Pseudomonas keratitis

Proteases are involved in the pathogenesis of Pseudomonas aeruginosa infections of the cornea. Although there are many potential roles for these enzymes, involvement in corneal stroma destruction with subsequent descemetocele formation and/or corneal perforation is an important example. This study examined the relationship of elastase and alkaline protease to corneal destruction as indicated by descemetocele formation. The protease content of the overnight Mueller-Hinton broth cultures of various strains of P. aeruginosa correlated with the production of descemetoceles both in the rabbit trauma model of Pseudomonas keratitis and upon intrastromal injection of filtrates of the overnight culture media. The levels of alkaline protease correlated better with descemetocele formation than those of elastase. The influx of inflammatory cells was not correlated with descemetocele formation within 24 to 48 hrs.

Dressing changes by specialized personnel reduce infection rates in patients receiving central venous parenteral nutrition

In 60 pediatric patients, 75 central venous catheters representing 1866 patient days were placed to provide parenteral nutrition. During the 21-month study period, surgical residents were responsible for dressing changes during the first 16 months and a specially trained nurse was responsible during the final 5 months. Twenty percent of the lines became infected. The infection rate was significantly higher in the lines cared for by residents, 28.8% compared to 3.3% in the lines cared for by the nurse. This occurred in spite of the lines being in place significantly longer in the nurse group (31.7 vs 20.3 patient days/line). These data indicate that a specially trained person using aseptic techniques can reduce infection rates in patients receiving central venous parenteral nutrition.

Tissue water relations of four co-occurring chaparral shrubs

Chaparral shrubs of California have a suite of morphological and physiological adaptations to withstand the prolonged summer droughts of a mediterranean climate. Not all species of chaparral have the same rooting depth and there is some evidence that those with shallow roots have tissue that is most tolerant to water stress. We tested this notion by comparing the tissue water relations of four co-occurring chaparral shrubs: Quercus durata, Heteromeles arbutifolia, Adenostoma fasciculatum, and Rhamnus californica. We used a pressure-volume technique and a dew-point hygrometer to metsure seasonal changes in osmotic potential when plant tissue was fully hydrated and osmotic potential at predawn, midday, and the turgor loss point. We also calculated seasonal changes in the minimum daily turgor potential, saturated weight/dry weight ratio of leaf tissue, and the bulk modulus of elasticity. We had information on the seasonal water use patterns and apparent rooting depths of these same four shrubs from a previous study (Davis and Mooney 1986). All evidence indicated that Rhamnus had shallow roots and Quercus deep roots. Our results indicated that the tissue water relations of our four co-occurring chaparral shrubs were not alike. Even though Rhamnus had shallow roots, it had the least xerophytic tissue. Seasonal osmotic potential and saturated weight/dry weight ratios were relatively high and bulk modulus of elasticity and minimum daily turgor potentials were low. Furthermore, even though Quercus had deep roots and experienced no seasonal water stress at our study site, its tissue water relations indicated relatively high tolerance to water stress. We conclude that seasonal drought tolerance of stem and leaf tissue of co-occurring chaparral shrubs does not necessarily correspond to rooting depth, to soil moisture resources available to the shrub, or to the degree of seasonal water stress experienced by the shrub.

Comparative water relations of adjacent california shrub and grassland communities

Much of the coastal mountains and foothills of central and southern California are covered by a mosaic of grassland, coastal sage scrub, and evergreen sclerophyllous shrubs (chaparral). In many cases, the borders between adjacent plant communities are stable. The cause of this stability is unknown. The purpose of our study was to examine the water use patterns of representative grasses, herbs, and shrubs across a grassland/chaparrel ecotone and determine the extent to which patterns of water use contribute to ecotone stability. In addition, we examined the effects of seed dispersal and animal herbivory. We found during spring months, when water was not limited, grassland species had a much higher leaf conductance to water vapor diffusion than chaparral plants. As the summer drought progressed, grassland species depleted available soil moisture first, bare zone plants second, and chaparral third, with one chaparral species (Quercus durata) showing no evidence of water stress. Soil moisture depletion patterns with depth and time corresponded to plant water status and root depth. Rabbit herbivory was highest in the chaparral and bare zone as indicated by high densities of rabbit pellets. Dispersal of grassland seeds into the chaparral and bare zone was low. Our results support the hypothesis that grassland species deplete soil moisture in the upper soil horizon early in the drought, preventing the establishment of chaparral seedlings or bare zone herbs. Also, grassland plants are prevented from invading the chaparral because of low seed dispersability and high animal herbivory in these regions.

Polymorphonuclear leukocyte kinetics in experimentally induced keratitis

The movement of polymorphonuclear leukocytes (PMNLs) into inflamed corneas was studied using a quantitative technique to measure PMNL chemotaxis in vivo. Our studies suggested that, in this model, most PMNLs enter the cornea through limbal vessels. A variety of bacterial agents, including viable bacteria, killed bacteria, culture filtrates, and endotoxin, were found to induce a significant corneal inflammatory response. Of the agents tested, viable Pseudomonas aeruginosa produced greatest inflammation. Host factors (serum, PMNLs) also induced movement of PMNLs into corneas, but only after preincubation with activating agents. Normal serum, resting PMNLs, and PMNL lysates derived from resting cells did not promote PMNL corneal ingress. These studies provide further insight into the movement of PMNLs into the inflamed cornea and information that may be of use in developing techniques to inhibit the corneal inflammatory response.

Endotoxin shock: prevented by naloxone in intact but not hypophysectomized rats

Previous studies established that naloxone reverses hypotension in endotoxin, hemorrhagic, and spinal shock. We studied endotoxin shock in hypophysectomized (Hx) rats, which have little circulating beta-endorphin. Hx or intact rats received surgically implanted jugular catheters for drug injection and aortic catheters for arterial blood pressure (MAP) recording. On the second day after implantation, rats were pretreated with either naloxone or saline. Two minutes later each rat received endotoxin. Following endotoxin, all rats showed a brief biphasic hypertensive-hypotensive response followed by stabilization of MAP near baseline. Within 20 min, all Hx rats, regardless of pretreatment, and the saline-treated intact rats, showed progressive hypotension (P less than 0.005). Only the naloxone-pretreated intact rats maintained a stable MAP. Plasma endorphin measured at 20 min was undetectable in Hx rats in contrast to intact rats (P less than 0.001); plasma corticosterone levels were likewise suppressed in the Hx rats (P less than 0.01). Thus (1) naloxone protected only the rats with an intact pituitary-adrenal-sympathetic system, and (2) pituitary endorphin is not required to generate endotoxin shock in hypophysectomized rats.

Postoperative wound infections in a children's hospital

A prospective study was made of postoperative wound infections at Milwaukee Children's Hospital for 1 year. Essentially all procedures requiring a skin incision were included. The clean surgical wound infection rate was 3.1% (26 infections in 849 cases). There were no significant differences in clean wound infection rates among the individual surgeons or among the four busiest surgical services. The occurrence of postoperative wound infections was associated with administration of prophylactic antibiotics, longer duration of surgical procedures and longer hospital stay before and after surgery. About 50% of patients having a clean surgical procedure were given prophylactic antibiotics. Prophylactic antibiotic were given for 4 days or more in about half the cases.

Interactions of neurotensin with brain dopamine systems: biochemical and behavioral studies

Intracisternal (i.c.) injection of neurotensin (NT) to rats or mice attenuated the locomotor hyperactivity induced by d-amphetamine, methylphenidate or cocaine, but not the increased activity induced by apomorphine or lergotrile. The reduction of methylphenidate-induced locomotor activity by i.c. NT was not due to an increased drug metabolism because i.c. NT did not change plasma methylphenidate concentrations. These actions of NT are distinct from those of the dopamine receptor antagonist haloperidol, which blocked the locomotor hyperactivity induced by all five stimulant drugs in rats. A further difference between NT and neuroleptics was demonstrated by the observation that i.c. NT did not block apomorphine-induced stereotypic behavior. In vitro, NT did not displace [3H]spiperone from its binding sites in homogenates of either the striatum or nucleus accumbens from rat brain. Moreover, i.c. injection of NT did not alter the subsequent in vitro binding of [3H]spiperone to membranes of the nucleus accumbens or striatum. In addition, NT did not alter basal or dopamine-stimulated adenylate cyclase activity in homogenates of the nucleus accumbens or striatum. However, i.c. injection of NT produced a significant increase in the concentrations of homovanillic acid, a major dopamine metabolite, in the nucleus accumbens, olfactory tubercles and striatum. In addition, the concentration of dihydroxyphenylacetic acid was increased in the nucleus accumbens and olfactory tubercles after i.c. NT. Peripheral injection of haloperidol produced qualitatively similar effects on dopamine metabolism, but the effects of haloperidol, unlike those of i.c. NT, were attenuated by apomorphine injection. Taken together, these data indicate that centrally administered NT affects certain brain dopamine systems without interacting directly with those dopamine receptors labeled by [3H]spiperone, coupled to adenylate cyclase or mediating the pharmacological effects of apomorphine.

Experimental Pseudomonas aeruginosa sepsis: absence of synergy between ticarcillin and tobramycin

An in vivo model of Pseudomonas aeruginosa sepsis was developed with normal and neutropenic guinea pigs injected intravenously with a strain of Pseudomonas demonstrated in vitro to be synergistically susceptible to ticarcillin and tobramycin. Therapy with ticarcillin, tobramycin, or a combination of the two starting 4 hr after intravenous injection of microorganisms was administered every 2 hr for periods up to 40 hr. Each therapy was associated with significant reductions in bacterial counts in blood, liver, spleen, and kidney compared with untreated animals. In no tissue in either normal or granulocytopenic animals did therapy with a combination of ticarcillin and tobramycin reduce bacterial counts significantly more effectively than did the better single antibiotic agent alone. These findings suggest that when ticarcillin and tobramycin are administered to animals at doses equivalent to therapeutic doses given in humans, a synergistic effect in reduction of bacterial counts in parenchymal organs and blood is not observed. These studies may help explain clinical reports in humans describing a lack of synergistic activity of combination antibiotic therapy in patients with Pseudomonas sepsis.

Factors that influence the efficacy of topical gentamicin prophylaxis for experimental Pseudomonas keratitis

We evaluated the efficacy of topical gentamicin prophylaxis for experimental Pseudomonas keratitis in rabbits by applying gentamicin in concentrations of 0.3 and 4 mg/100 ml, in both solution and ointment vehicles, one or four hours after a superficial stromal scratch was infected topically with Pseudomonas organisms. Under these conditions the most effective prophylaxis was that given early, in solution, and in high concentration.

Increased susceptibility to infection in experimental xerophthalmia

Vitamin A-deficient rabbits were used to evaluate the role of secondary bacterial infection in the development of keratomalacia and to describe the resultant clinical and morphologic alterations. The conjunctival sacs of vitamin A-deficient rabbits at different stages of corneal involvement were inoculated with Pseudomonas aeruginosa topically. Approximately two weeks after inoculation, corneal ulceration with stromal melting developed in one of three eyes with severe punctate keratitis and in four of seven eyes with xerosis. Ulceration did not develop in any of the eight eyes with early epithelial graying or mild punctate keratitis. Inflammatory cells (primarily polymorphonuclear leukocytes) infiltrated the anterior corneal stroma of infected corneas. Liquefaction of collagen was observed in association with bacteria alone, as well as in association with polymorphonuclear leukocytes. No signs of infection were observed after conjunctival inoculation of Pseudomonas in the eyes of nine control rabbits.

Experimental bacterial keratitis: a quantitative model of leukocyte migration following transfusion

A model for the study of polymorphonuclear leukocyte (PMN) migration after transfusion employing induction of keratitis in guinea pigs was developed. Initial studies demonstrated that compared with other agents, intracorneal injection of Pseudomonas aeruginosa following in vivo labelling of PMN by administration of 3H-thymidine produced the greatest influx of radiolabelled PMN into corneas. In subsequent studies, donor peritoneal PMN were radio-labelled by injection of donors with 3H-thymidine. Neutropenia was induced in recipients by whole body irradiation, and they were infected intracorneally with Pseudomonas prior to transfusion. Corneal radioactivity was assayed 24 h after induction of keratitis and the number of donor PMN in corneas was calculated. Half-life of transfused PMN in non-neutropenic recipients was 1.9 h. Arrival of labelled PMN at infected corneas in recipient animals ranged between 0.1-1.0% of transfused cells. Exposure of donor PMN to sonication or to 45 degrees C for 20 min reduced the proportion of PMN arriving at infected corneas (P less than 0.001). Storage of PMN for 24 h at 4 degrees C led to a greater ingress of donor PMN compared with storage at 37 degrees C (P less than 0.01). This model allows quantitation of in vivo PMN function after transfusion and should allow assessment of the effects of most aspects of PMN transfusion technique upon such function.

Experimental Pseudomonas keratitis in the rabbit: bacteriologic, clinical, and microscopic observations

Uniformly severe corneal infections were produced in rabbits by intracorneal injection of a few viable Pseudomonas aeruginosa. The bacteria multiplied rapidly, and within 24 hr, about 10 million organisms were present. The numbers remained stable thereafter. Polymorphonuclear leukocytes (PMNs) began to infiltrate peripheral stroma 24 hr after inoculation. By 32 hr, ring-shaped dense accumulations of PMNs were apparent in the anterior stroma with moderate stromal edema. By 48 hr, the anterior one third of central stroma was severely involved with abscess formation and loss of epithelium, and PMNs had invaded full corneal thickness. The area of liquefactive necrosis eventually involved the entire cornea from limbus to limbus, and collagen staining was lost. Transmission electron microscopy revealed the accumulation of small electron-dense particles in association with collagen fibrils and degranulating PMNs.