Natural Field Spread of Mild and Severe Isolates of Citrus Tristeza Virus in Florida.

The effectiveness of five different aphid control regimes in delaying movement of mild and severe isolates of citrus tristeza virus (CTV) into a CTV-free sweet orange scion on sour orange rootstock block was monitored annually for 5 years, using severe isolate-specific and isolate-nonspecific monoclonal antibodies. The average percentage of trees infected with a severe isolate of CTV was 32, 32, 20, 25, and 28 for trees treated with Temik, Temik + Meta-Systox R (MSR), MSR, stylet oil, or no aphid control, respectively, at the conclusion of the experiment (5 years). These percentages were not significantly different (P ≤ 0.05). The average percentage of trees infected only with mild isolates was 13, 10, 7, 7, and 17 for the above treatments, respectively. The infection with mild isolates was significantly greater (P ≤ 0.05) with no aphid control than with stylet oil or MSR treatments.

Breakdown of Cross-Protection of Grapefruit from Decline-Inducing Isolates of Citrus tristeza virus Following Introduction of the Brown Citrus Aphid.

A 21-year-old replicated field planting of 84 'Ruby Red' grapefruit trees cross-protected with three mild isolates of Citrus tristeza virus (CTV) was assessed for decline-inducing and non-decline-inducing isolates of the virus 5 years after the brown citrus aphid (BrCA) (Toxoptera citricida Kirkaldy) first was established in the experimental area. Prior to the introduction of the BrCA, the cross-protecting mild isolates had significantly reduced detectable infection with decline-inducing isolates of CTV for 16 years (average infection of 13% in cross-protected trees compared with 67% in unprotected trees). After the introduction of the BrCA, infections with decline-inducing CTV (measured by enzyme-linked immunosorbent assay) were 57, 81, and 71% for trees protected with three mild isolates, respectively, compared with 95% in unprotected trees. These results suggest that the introduction of BrCA accelerated the breakdown of cross-protection against decline-inducing isolates of CTV in grapefruit.

A Psorosis-Like Agent Prevalent in Florida's Grapefruit Groves and Budwood Sources.

Rio Grande Gummosis (RGG) is one of the most serious diseases of grapefruit in the Indian River region of Florida. Experiments were conducted to determine if a graft-transmissible agent was associated with this disease in commercial grapefruit, and if any such agent was present in scion sources used for grapefruit propagation. Indexing data from indicators revealed that 79% and 31% of the commercial grapefruit and scion trees, respectively, contained a psorosis-like agent (PLA). The PLA was present in both RGG-affected and symptomless trees. We conclude that Florida's grapefruit propagation sources are contaminated with a PLA that is now widespread in commercial plantings.

Cross-Protection of Grapefruit from Decline-Inducing Isolates of Citrus Tristeza Virus.

The ability of three mild isolates of citrus tristeza virus (CTV) to prevent natural infection of 84 Ruby Red grapefruit on sour orange rootstock by aphid-transmitted, decline-inducing isolates of CTV was assessed by symptoms and verified by enzyme-linked immunosorbent assay (ELISA) after 16 years. Of 21 trees in each of four treatments protected by the DD 102 bb, Guettler HS, and DPI 1-12-5-X-E mild CTV isolates, 14, 10, and 14% were infected by severe isolates (MCA13 monoclonal antibody reactive) compared with 67% for unprotected control trees. The health of trees protected by the DD 102 bb CTV isolate was significantly better than that of unprotected control trees as measured by decline, tree ratings, and tree height. These data suggest that infection by certain mild isolates of CTV can cross-protect grapefruit trees on sour orange rootstock from decline-inducing isolates of CTV that are prevalent in the Indian River region of Florida.

[Blood gas analysis and evaluation of pulmonary functional damage in bronchiolitis]. / Indagine emogasanalitica e valutazione del danno funzionale polmonare nella bronchiolite.

212 Sucklings affected with bronchiolitis were evaluated monitoring values of haematic gases and acid-base balance. The patients were differentiated in three groups: Hypoxemia--Hypercapnia (3.7%). Hypoxemia--Normocapnia (38.2%). Normoxemia--Hypocapnia (58.1%). Metabolic acidosis was detected in 55.1% of cases. The different value of haematic gases was correlated with entity of the pulmonary functional damage.

[Bronchiolitis. Our clinical experience in the 4 years from 1981 to 1984]. / La bronchiolite. La nostra esperienza clinica nel quadriennio 1981-1984.

The clinical experience of 661 children with bronchiolitis is reported in four-years period to gain a better understanding of diagnosis and pathogenesis of bronchiolitis. Upper airways infections, expiratory dyspnea, clear sound by chest percussion, vesicular rales and whistling by chest auscultation, air trapping on the chest radiography were considered as essential data of diagnosis. It was found in 595 patients: expiratory dyspnea, air trapping, vesicular r. and whistling in 85% and whistling only in 15%; hypoxemia in 20% combined with hypercapnic acidosis in 10%; normoxemia in 80% combined with hypocapnia in 54%; hyperlactemia in 64% combined with an increment in the serum of CPK in 50% and of GPT in 30%; virus were cultured in 27%, adenovirus and RSV were identified in 90%. Instead it was found in 66 patients: air trapping but no difficult breath, with normal chest auscultation; crisis of cyanosis or paleness-cyanosis chilly sweat in 80% were motive of admission. The clinical and/or radiological features of "air trapping" were considered as essential symptoms and signs of bronchiolitis. The insufficient systemic perfusion was considered as a frequent occurrence and as cause for sudden respiratory and circulatory emergency.

On the stability of delay equation models of simple human stretch reflexes.

Human stretch reflexes (SRs) are often too weak and ineffectual to provide adequate postural regulation or rhythmic movement boosting (e.g. in ankle pushoff at the end of stance phase in fast running). Recent improvements in methods of artificially enhancing skeletomotor responses, especially in therapeutic regimens, should not be widely employed until the clonus-resisting stability properties of SRs are better understood. We formulate an idealized linear servo model of a segmentally-mediated SR system which includes the often ignored electromechanical coupling delay. For typical closed-loop (delay/gain) ratios, the model is shown to be unstable for all values of loop gain when operating as a position servo, but maximally stable when operating as a velocity servo. We claim that the velocity servo or more of its nonlinear relatives is a better model for some well studied SRs than, e.g., Houk's stiff muscle hypothesis. We also present evidence that even feeble and quickly saturating monosynaptic postural servos are always unstable if operated as pure position regulators.

[Low doses of insulin--comparison between hyperosmolar nonketotic coma and diabetic ketoacidosis (author's transl)]. / Pequenas doses de insulina--comparação entre o coma hiperosmolar não-cetótico e a cetoacidose diabética.

The authors present a comparison between the results achieved in the treatment of 11 cases of nonketotic hyperosmolar "coma" and 13 cases of diabetic ketoacidosis using low doses of intramuscular insulin hourly. Surprisingly both, larger amounts of insulin and longer periods were needed to compensate the metabolic disturbance of the nonketotic hyperosmolar "coma" cases when compared to the ketoacidosis ones. The data obtained in this study suggest a possible direct relationship between the initial urea levels and the total amount of insulin needed to reduce the initial glycemia to a normal glycemic level.

Inadequate treatment of syphilis in pregnancy.

Pregnant women with untreated syphilis have high rates of adverse pregnancy outcome. Early syphilis in pregnancy, if not treated, results in 40% loss either by spontaneous abortions, stillbirth, or perinatal death. Another 40% of such pregnancies result in an infant born with congenital syphilis. Only 20% of such pregnancies result in a normal infant. Currently recommended treatment of early syphilis in pregnant women uses a dosage of 2.4 million U of benzathine penicillin G. Because of the potentially disastrous effect syphilis has on pregnancy outcome, the occurrence of any treatment failure must be considered seriously. In this brief report we present clinical summaries of four pregnant women treated for syphilis who represent probable treatment failures.

Congenital syphilis revisited.

Despite decades of experience with congenital syphilis, problems still arise in case definition, diagnostic evaluation, treatment, and follow-up. We reviewed all 50 cases of early congenital syphilis reported to the State of Texas in 1982. A large proportion of the infants were premature (39%), of low birth weight (38%), and symptomatic at birth (62%). Because of these findings, we believe that possible cases of asymptomatic congenital syphilis in Texas may be under-reported. Laboratory and/or roentgenographic findings were important to confirm the diagnosis of congenital syphilis. Over half of the asymptomatic infants had positive results of cerebrospinal fluid VDRLs. After diagnosis, the treatment of infants with penicillin varied considerably. While all 47 living infants were treated with penicillin, 21 different regimens were used. We urge all physicians to perform complete diagnostic evaluations on suspected infants consisting of a quantitative serum test for syphilis, serum IgM levels, a cerebrospinal fluid VDRL, roentgenographs of the long bones, and dark-field microscopy where indicated. Additionally, infants and their families need appropriate follow-up after treatment.

Congenital syphilis. Why is it still occurring?

A total of 159 cases of early congenital syphilis were reported in the United States during 1982, with Texas reporting 50 cases. We reviewed these Texas cases to identify the most important characteristics on which to focus control efforts. Thirty-eight mothers were 25 years of age or younger; 33 were unmarried. All were from minority groups. No congenital syphilis occurred in whites. Blacks were twice as likely as Hispanics to have an infected infant. Foreign-born Hispanic women were three times more likely to be delivered of an infected child than Hispanics born in the United States. Attendance at prenatal care facilities significantly affected the risk of being delivered of an infected child in both black and Hispanic women; 31 women received no prenatal care. Based on these findings, congenital syphilis in Texas can be reduced primarily through improving prenatal care for high-risk populations and by refining casefinding efforts to control infectious syphilis in the community.