Photosynthetic responses of a dominant C4 grass to an experimental heat wave are mediated by soil moisture.

Extreme heat waves and drought are predicted to increase in frequency and magnitude with climate change. These extreme events often co-occur, making it difficult to separate their direct and indirect effects on important ecophysiological and carbon cycling processes such as photosynthesis. Here, we assessed the independent and interactive effects of experimental heat waves and drought on photosynthesis in Andropogon gerardii, a dominant C4 grass in a native mesic grassland. We experimentally imposed a two-week heat wave at four intensity levels under two contrasting soil moisture regimes: a well-watered control and an extreme drought. There were three main findings from this study. First, the soil moisture regimes had large effects on canopy temperature, leading to extremely high temperatures under drought and low temperatures under well-watered conditions. Second, soil moisture mediated the photosynthetic response to heat; heat reduced photosynthesis under the well-watered control, but not under the extreme drought treatment. Third, the effects of heat on photosynthesis appeared to be driven by a direct thermal effect, not indirectly through other environmental or ecophysiological variables. These results suggest that while photosynthesis in this dominant C4 grass is sensitive to heat stress, this sensitivity can be overwhelmed by extreme drought stress.

Macrophage-HIV interaction: viral isolation and target cell tropism.

Viral isolates were recovered by cocultivation on macrophage colony-stimulatingfactor (MCSF)-treated monocyte target cells from peripheral blood mononuclear cells (PBMCs) in 25 out of 27 patients seropositive or at risk for HIV infection. Frequency of virus recovery was independent of the patient's age, sex, numbers of CD4+ T cells, clinical stage or zidovudine (azidothymidine) therapy. Sixteen out of 19 HIV isolates were serially passaged in MCSF- treated monocytes. Five out of five virus isolates were also passaged in phytohemagglutinin/interleukin-2 (PHA/IL-2)-treated lymphoblasts. In lymphoblasts, no qualitative or quantitative differences were observed between these isolates and human T-cell leukemia virus IIIB (HTLV-IIIB) for (1) release of p24 antigen reverse transcriptase, and infectious virus, (2) induction of typical cytopathic effects (cell syncytia in 3-10% of cells) and cell lysis, (3) frequency of infected cells (5-20% of PBMC) as detected by in situ hybridization for HIV RNA, (4) down-modulation of T cell plasma membrane CD4, and (5) site of progeny virion assembly and budding (plasma membrane only with no intracytoplasmic accumulation of virus). Progeny virus recovered from infected lymphoblasts was fully infectious for other lymphoblasts, but failed to infect MCSF-treated monocytes. Detailed analysis of target cell tropism among HIV isolates showed that HIV isolated in monocytes infected both monocytes and lymphoblasts; progeny virus isolated in lymphoblasts infected only T cells. HIV interacts differently with monocytes and T cells. Understanding this interaction may more clearly define both the pathogenesis of HIV disease and strategies for therapeutic intervention.

Kinetics of cellular and cytokine responses in a chimeric mouse model for the study of staphylococcal enterotoxin B pathogenesis.

The mechanisms by which superantigens, such as staphylococcal enterotoxin B (SEB), contribute to microbial pathogenicity have been poorly defined. The study of such pathogenic processes has been hampered by the lack of an adequate animal model. We utilized a previously described murine chimeric model to determine the cytokines and cell populations that might be involved in SEB toxicity. In the absence of bone marrow transplantation (BMT), all total body irradiated (TBI) mice died, while all transplanted mice survived up to 6 months. Compared with non-TBI and non-BMT mice, chimeric mice had an increased percentage of CD11b (Mac-1)-positive splenocytes (17 vs. 59%, P < 0.05) and decreased CD45R-positive (B) cells (33 vs. 6%, P < 0.05) at 6 weeks after BMT. The relative numbers of splenocyte CD4 and CD8 cells were similar in chimeric and normal mice. Susceptibility of chimeric animals to 10 or 100 microg SEB was time-dependent: no mice challenged at 2 weeks post-BMT died, but 15% of mice challenged at 4 weeks and 50% of those challenged at 6-8 weeks died. Compared with TBI and non-BMT C3H/HeJ mice, SEB-challenged chimeric mice at 6-8 weeks had (1) increased splenocyte mRNA expression for: IFN-gamma (3.5 x optimally at 1 h), TNF-alpha (6.5 x at 2 h), IL-6 (4.8 x at 4 h), IL-1beta (8.4 x at 4 h), IL-2 (4.7 x at 4 h), and IL-10 (3 x at 16 h), and (2) increased and earlier peak serum levels of IFN-gamma, IL-6, IL-1beta and IL-2, but no increase in serum TNF-alpha or IL-4. These data support the hypothesis that the decreased percentage of B cells and increased macrophages in chimeric mice lead to enhanced T cell-macrophage interactions after SEB administration and a lethal burst of T cell and macrophage cytokine release. This model will provide insight into cell populations and mechanisms that mediate superantigen-induced toxicity.

Penile neurofibromas.

Unless omitted and underreported, penile neurofibromas are rare. Between January 2, 1982 and December 31, 1997 through the USF Regional Genetics Program we evaluated 566 propositi with suspected or clinically diagnosed neurofibromatosis (NF1, NF2, segmental NF=NF5, NF/Noonan syndrome, familial café-au-lait macules, and solitary neurofibroma, NF). These index cases were part of 32,715 families evaluated during the period. NF1 was the diagnosis in 361; 2 of them had penile NFs. A toddler presented with congenital plexiform NF of the penile shaft and another propositus developed two small subcutaneous NFs, on the penile shaft and on the left scrotal wall, respectively. A review documented 26 additional patients with penile NF. As to the pathogenesis of the NF1 lesions, a paracrine growth model including the multiple levels of regulation of expression of the NF1 gene appeared more plausible than the loss of heterozygosity (LOH) model, which ignores the complexity of the paracrine growth mechanism.

Descemet's membrane detachment by sodium hyaluronate.

The inadvertent injection of sodium hyaluronate (Healon) just anterior to Descemet's membrane during an extracapsular cataract extraction resulted in a corneal opacity. No extraordinary measures were taken to remove this substance. The opacity resolved over five months, with a final visual acuity of 20/25 and a reduction in specular microscopic cell density from 2,600 to 2,100/sq mm. Sodium hyaluronate was injected in an analogous manner into eight rabbit corneas. The eyes were enucleated, and histologic sections were examined 1, 5, 9, and 14 days later. Sodium hyaluronate injected just anterior to Descemet's membrane was found to incite an acute mild granulocytic response, which is followed by a macrophage invasion and ingestion of this substance. We recommend a conservative approach when the central portion of Descemet's membrane is detached by sodium hyaluronate during anterior segment surgery.

Pediatric ocular sarcoidosis.

Sarcoidosis is an uncommon cause of childhood uveitis. However, the ophthalmologist familiar with the clinical features of childhood sarcoidosis can play a key role in the diagnosis and treatment of this disorder. Two subsets of pediatric sarcoidosis are identified. The 8-15 year age group has almost universal lung involvement, with the eye, skin, liver, and spleen involved in 30-40% of cases. Children 5 years of age and under are characterized by the triad of uveitis, arthropathy, and skin rash. The epidemiology, clinical features, diagnostic evaluation, and ocular management of pediatric sarcoidosis are reviewed. The clinical and laboratory findings that distinguish sarcoidosis from other causes of childhood uveitis are discussed.

Survivability and infectivity of viscerotropic Leishmania tropica from Operation Desert Storm participants in human blood products maintained under blood bank conditions.

To assess the potential for leishmaniasis being transmitted through blood transfusion, we studied the survival of Leishmania in blood products under blood bank storage conditions. We report that L. tropica- or L. donovani-contaminated transfusable blood products are a risk to the blood supply for at least 25 days postdonation under blood bank general conditions. The blood components that have been implicated are whole blood, packed red blood cells, platelet concentrate, and frozen-deglycerolized red blood cells, but not, as would be expected, fresh frozen plasma. Blood units containing four infected monocytes per milliliter of blood with a mean of three amastigotes per monocyte contain viable parasites for 15 days under blood bank storage conditions. Furthermore, animal studies showed the presence of parasites in the blood of cutaneously infected animals and the possibility of transmitting the disease to healthy experimental animals by blood transfusion from infected animal donors. Three of three BALB/C mice showed metastasis to the lower extremities and face after they received 0.25 ml of blood from a CPDA-1 bag seeded with 1.5 x 10(5) amastigotes per ml of blood kept under blood bank conditions for 30 days. This proves that Leishmania not only survives blood banking procedures and storage conditions but that the parasite retains its infectivity. The results of this study and the recent demonstration of L. tropica-infected monocytes in the blood of a patient returning from Southwest Asia suggests that transfusion-associated leishmaniasis can occur.

Topical vancomycin formulation for methicillin-resistant Staphylococcus epidermidis blepharoconjunctivitis.

We successfully treated two patients with severe Staphylococcus epidermidis blepharoconjunctivitis by means of a topical vancomycin hydrochloride solution (50 mg/ml) prepared with sterile water. Aqueous vancomycin preparations, however, cause significant ocular irritation probably because of low pH and osmolality values. Solutions prepared with normal saline (5 mg/ml) and phosphate-buffered artificial tears (5 mg/ml and 50 mg/ml) were significantly less irritating and possessed equivalent in vitro antimicrobial activity. Topical vancomycin should be used only when commercially available antibiotics are inadequate.

Clinical recognition and management of patients exposed to biological warfare agents.

Concern regarding the use of biological agents (bacteria, viruses, or toxins) as tools of warfare or terrorism has led to measures to deter their use or, failing that, to deal with the consequences. Unlike chemical agents, which typically lead to severe disease syndromes within minutes at the site of exposure, diseases resulting from biological agents have incubation periods of days. Rather than a paramedic, it will likely be a physician who is first faced with evidence of the results of a biological attack. Provided here is an updated primer on 11 classic BW and potential terrorist agents to increase the likelihood of their being considered in a differential diagnosis. Although the resultant diseases are rarely seen in many countries today, accepted diagnostic and epidemiologic principles apply; if the cause is identified quickly, appropriate therapy can be initiated and the impact of a terrorist attack greatly reduced.

Hetero- and isosexual pseudoprecocity associated with testicular sex-cord tumors in an 8 year-old male.

Enlargement of the right breast, axillary hair, and acceleration of linear growth rate were first noted at 8 years of age in an otherwise healthy male with no known exposure to exogenous hormones. At 9.5 years of age the right subareolar mass was excised; histologic examination revealed fibrous breast tissue. Subsequently pubic hair appeared. At 10.7 years of age, the patient complained of right inguinal pain after a minor injury. Examination revealed a tall (height age 12.7 years), mature, muscular boy with enlarged (R: 5 x 3 x 2 cm; L: 3 x 2 x 3 cm) firm, irregular testes, Tanner stage II pubic hair, and modest axillary hair. No perioral pigmentation was present. Testicular ultrasonography revealed multilobular echogenic foci with calcifications. Bone age was 13 years, the LH and FSH secretory responses to GnRH were minimal (LH: < 0.038-->0.28 mIU/ml; FSH: < 0.063-->0.11 mIU/ml), and basal serum testosterone (< 10 ng/dl) and estradiol (< 10 pg/ml) values were undetectable. Following administration of human chorionic gonadotropin (hCG), the serum testosterone concentration increased to 275 ng/dl, while estradiol remained unmeasurable. Spermatic vein concentrations of testosterone were undetectable in the basal state and increased after hCG administration. After bilateral orchiectomy, pathologic examination revealed multifocal tumors composed of brightly eosinophilic, large polygonal cells arranged in nests, cords, and clusters within dense connective tissue or mucinous stroma with lamellar calcifications of varying sizes. These pathologic findings were compatible with a large cell calcifying Sertoli cell (sex-cord)tumor of the testes. Testosterone, estradiol, immunoreactive and bioactive aromatase activity were not detectable in the tumor. Thus, both heterosexual (gynecomastia) and isosexual (increased musculature, pubic and axillary hair) precocious puberty may occur in boys with testicular sex-cord tumors.

Circulating levels of tumour necrosis factor, interleukin 6 and proteolytic activity in a murine model of burn and infection.

Cytokines and proteinases have both been implicated as mediators in the inflammatory response associated with trauma and sepsis. Using a burned-infected mouse model, it was previously found that mortality is proportional to the amount of proteolytic activity (PA) in the circulation. However, little is known about circulating cytokine levels in hosts that are both burned and infected. With this mouse model, both tumour necrosis factor (TNF) and interleukin 6 (IL-6) were upregulated by a burn and by an infection. Burn plus infection produced an additive effect on each cytokine, but IL-6 levels correlated better with mortality. Treating mice with the proteinase inhibitor aprotinin immediately preburn and infectious challenge significantly decreased IL-6, PA and mortality. This may be a clinically relevant model for studying mediators in burned and/or septic hosts.

Results of a combined adjustable recession and posterior fixation suture of the same vertical rectus muscle for incomitant vertical strabismus.

PURPOSE: The posterior fixation suture (fadenoperation) is an effective treatment for complicated incomitant vertical strabismus. Traditional operative methods do not permit the simultaneous use of an adjustable recession of the same muscle. METHODS: Seven patients with incomitant vertical strabismus and diplopia were treated with a combined adjustable recession and posterior fixation suture of the same vertical rectus muscle. Preoperative vertical misalignments in the primary position ranged from 4 to 10 prism diopters. Vertical incomitance from the primary position into the field of action of the recessed vertical rectus muscle ranged from 6 to 30 prism diopters (mean, 17 prism diopters). This was the sole operation in five patients and was combined with other vertical muscle surgery in two others. RESULTS: All seven patients experienced improvement in their diplopia. Five of 7 patients (71%) required postoperative adjustments to achieve orthophoria in the primary position. This combined procedure reduced large deviations in the field of action of the recessed vertical muscle in all cases. Six of 7 patients (86%) did not require prismatic correction after this operation. One patient required prism only in his reading glasses. CONCLUSIONS: A combined adjustable recession and posterior fixation suture of the same vertical rectus muscle was effective in reducing or eliminating vertical incomitant strabismus.

Bacteriologic and histologic features in mice after intranasal inoculation of Brucella melitensis.

OBJECTIVE: To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice. ANIMALS: Female Balb/c mice, 6 to 8 weeks old. PROCEDURE: Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy. RESULTS: Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 10(3), 10(4), and 10(5) CFU. Recovery of brucellae from the lungs was possible early in infection with 10(1), 10(3), and 10(5) CFU, but only the group inoculated with 10(5) CFU consistently yielded quantifiable bacteria. At a dose of 10 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 10(3) CFU. At an inoculum of 10(5) CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis. CONCLUSION AND CLINICAL RELEVANCE: Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice.

Results of a single lateral rectus resection for divergence and partial sixth nerve paralysis.

A single 5.5-millimeter to 8.0-millimeter lateral rectus resection eliminated diplopia in five of six adult patients with divergence paralysis and in all three patients with a sixth cranial nerve paresis. Preoperative distance esotropia ranged from 11 to 20 prism diopters in primary gaze. Prism therapy failed in seven of nine patients. Lateral incomitance was reduced in three patients with a mild limitation of abduction preoperatively, but was not induced in the six patients with divergence paralysis. Significant overcorrection of the near esodeviation did not occur. A single lateral rectus resection can effectively eliminate diplopia in selected patients with divergence and partial sixth nerve paralysis.

Orbital and childhood sarcoidosis.

Orbital infiltration, anterior uveitis, disc edema, choroiditis, erythema nodosum, and polyarticular arthritis due to sarcoidosis occurred in a five-year-old child who presented with unilateral proptosis. Diagnosis was enhanced by computerized tomography of the orbit, and confirmed by synovial biopsy findings. This patient's course illustrates the importance of thorough and frequent ocular examinations in childhood uveitis associated with systemic disease and demonstrates an unusual finding of orbital sarcoidosis. Childhood sarcoid arthritis may be misdiagnosed as juvenile rheumatoid arthritis. Familiarity with the ocular and systemic findings may lead to the correct diagnosis.

Optic disc drusen in children.

Forty children with pseudopapilledema due to optic disc drusen (31 bilateral, nine unilateral) were studied retrospectively to characterize the early natural history of this condition. The average age at the first examination was 10.2 years (range 3.6 to 19.5 years), and the mean follow-up period was 44 months. Discrete hyaline bodies or papillary calcifications were first noted in one or both eyes with pseudopapilledema at a mean age of 12.1 years in 38 of 40 cases. Decreased visual acuity due to drusen occurred in only one eye due to subretinal neovascularization. Visual fields obtained in 35 eyes (21 patients) with pseudopapilledema showed an enlarged blind spot (9), an inferior arcuate/sector/or altitudinal defect (6), or both (3) in 18 eyes. Our study suggests that discrete papillary calcifications or hyaline bodies frequently emerge and visual field deficits are commonly detectable in the second decade of life in patients with pseudopapilledema due to optic disc drusen.

Optic disc drusen and primary megalencephaly in children.

Three patients with primary megalencephaly were identified among 40 children seen in our clinic with pseudopapilledema due to optic disc drusen. These patients were genetically unrelated and did not have cutaneous hemangiomas, distinguishing their condition from the Riley-Smith syndrome. Although the nature of the relationship between optic disc drusen and primary megalencephaly is not clear, we feel that the two conditions have more than a chance association. A clinically important consideration is that the concomitant occurrence of pseudopapilledema due to optic disc drusen and a large head due to primary megalencephaly may lead to an erroneous diagnosis of increased intracranial pressure in children.

Subretinal neovascularization in children and adolescents.

Subretinal neovascular membranes (SRNVM) in the pediatric population are rare. The clinical presentation, etiology, course, and management of SRNVM in 25 children (27 eyes) were studied retrospectively. Inflammatory or infectious conditions predominated (10 of 25). Eleven of 19 untreated SRNVM (58%) spontaneously involuted, with 9 of these 11 achieving a final visual acuity of 20/50 or better. A hyperpigmented ring on fluorescein angiography was associated with 9 of the 11 involuted SRNVM. The presence of this pigmented ring may help to identify those cases with a better visual prognosis.

How I Manage Testicular Injury.

In brief: The pain and swelling that often follow testicular injuries can make it difficult to distinguish a contusion from a severe injury. An accurate diagnosis is imperative because in cases of testicular rupture or intrascrotal bleeding, surgery may be necessary to save the testicle. If scrotal swelling makes examination of the testis difficult, transillumination or ultrasound may help. Aspiration of the scrotum is rarely indicated for diagnostic reasons. A contusion generally can be treated with bed rest and oral analgesics, but a spermatic cord block may be used if the pain is very severe. If testicular rupture cannot be ruled out, prompt urological referral is appropriate.

Theory and Management of Exercise-Related Hematuria.

In brief: The pathogenesis of exercise- related hematuria is not clearly understood. This review shows that the most important factors are the degree of aerobic demand and the duration of exercise. Dehydration, age, and diet are also implicated. The authors propose a theory based on increased vascular resistance, cortical shunting, and spiral calicine vessels. They say the problem seems to be benign, because athletes have no increased incidence of renal disease. After the initial evaluation to rule out occult urologic pathology, recurrences do not require complete reevaluation if they are characteristic of the previous episodes and if the urine clears in 24 to 48 hours.