Trade-offs between succulent and non-succulent epiphytes underlie variation in drought tolerance and avoidance.

Epiphyte communities comprise important components of many forest ecosystems in terms of biomass and diversity, but little is known regarding trade-offs that underlie diversity and structure in these communities or the impact that microclimate has on epiphyte trait allocation. We measured 22 functional traits in vascular epiphyte communities across six sites that span a microclimatic gradient in a tropical montane cloud forest region in Costa Rica. We quantified traits that relate to carbon and nitrogen allocation, gas exchange, water storage, and drought tolerance. Functional diversity was high in all but the lowest elevation site where drought likely limits the success of certain species with particular trait combinations. For most traits, variation was explained by relationships with other traits, rather than differences in microclimate across sites. Although there were significant differences in microclimate, epiphyte abundance, and diversity, we found substantial overlap in multivariate trait space across five of the sites. We found significant correlations between functional traits, many of which related to water storage (leaf water content, leaf thickness, hydrenchymal thickness), drought tolerance (turgor loss point), and carbon allocation (specific leaf area, leaf dry matter content). This suite of trait correlations suggests that the epiphyte community has evolved functional strategies along with a drought avoidance versus drought tolerance continuum where leaf succulence emerged as a pivotal overall trait.

Differential antibody responses in 6.B major histocompatibility (B) complex congenic chickens.

Lines 6.6-2 (B2B2) and 6.15-5 (B2B2), congenic for the major histocompatibility (B) complex with > 99.9% background gene uniformity, were used to examine primary antibody responses to two antigens. In each of two trials, 1 mL of 5% SRBC, a T cell-dependent antigen, or 0.1 mL of Brucella abortus (BA), a T cell-independent antigen, was injected into separate groups of each B genotype aged 3 and 6 wk. Blood samples were taken from the chickens 7 d after immunization. Serum titers (log2) for both total antibody and mercaptoethanol (ME)-sensitive antibody to detect IgG were assayed by microtiter procedures. Least squares analysis of variance and Fisher's protected Least Significant Difference at P < 0.05 were used to evaluate the data. The total anti-SRBC antibody titer was significantly higher in B5B5 chicks than in B2B2 chicks at 4 and 7 wk of age. There was no significant difference in ME sensitive antibody to SRBC. Chicks of the B5B5 genotype also had significantly higher total and IgG antibody titers to BA at both ages than B2B2 chicks. The results indicate that 4- and 7-wk-old B5B5 chicks had a significantly stronger antibody response to SRBC or BA than B2B2 chicks.

Behavior change in the funny papers: feedback to cartoonists on safety belt use.

A multiple baseline across 8 nationally syndicated cartoonists evaluated the effects of personal advocacy letters encouraging presentations of a specific prevention message--the depiction of safety belt use in comic strips showing motor vehicle occupants. During baseline these cartoonists depicted safety belt use in only 15% (6 of 41) of their strips with occupied vehicles, but following receipt of a personal letter requesting safety belt use 41% (42 of 102) of their strips depicted safety belt use. Four cartoonists showed clear and immediate increases in depiction of safety belt use, 2 demonstrated delayed and somewhat less consistent belt use, and 2 cartoonists showed no change. The approach and results are discussed with regard to advocacy efforts intended to influence presentation of prevention messages in the media.

Anopheles neomaculipalpus, first record for Guatemala.

Anopheles neomaculipalpus is being confirmed in Guatemala for the first time, based on adult females and larvae collected in distinctly different parts of the country. Habitat data are also given.

Market research in the NHS: the Colchester health survey.

In summary, this survey showed that market research is both necessary and feasible: necessary because there is no other way of getting information for health promotion; and feasible because the quality of results is certainly good enough to shape policy and management action. We believe that such techniques should become routine in many other areas of the health service.

Positional nystagmus of central type and its neural mechanism.

Observations of Hallpike (1967) suggested that the neural mechanism responsible for positional nystagmus of central type, the direction-changing type of Nylén, was dependent upon derangement of compensatory eye reflexes subserved by neck proprioceptors and/or otolith organs in the presence of damage to the medial vestibular nuclei. Clinical studies together with autopsy evidence have demonstrated that this phenomenon may present in the absence of otolith function thus confirming Hallpike's thesis that positional nystagmus of central type may well depend on an abnormal neck reflex.

The mechanism and clinical significance of optokinetic nystagmus.

Observation of optokinetic nystagmus may be of invaluable help in the diagnosis of lesions of the vestibular pathways at all levels from the labyrinth to the cerebral cortex and facilities for its observation are an essential item of modern otological equipment. The majority of the disorders that had been discussed can be recognized on clinical examination with the use of a small optokinetic drum with mechanically or electronically controlled speeds (Table I). In certain cases electro-nystagmographic records may provide further and more precise information.

The rationale and technique of head exercises in the treatment of vertigo.

The central compensation mechanisms for vertigo resulting from vestibular lesions are described together with the scientific basis for head exercises in vestibular rehabilitation. The indications and contra-indications for head exercises are discussed and the Cawthorne-Cooksey regime of exercises illustrated.

Intramuscular iron-dextran and susceptibility of neonates to bacterial infections. In vitro studies.

An increased incidence of E. coli sepsis has been observed in neonates given intramuscular iron-dextran for prevention of iron deficiency. Mechanisms for this apparent effect on susceptibility to infection were investigated by comparing phagocytic and antibacterial functions in paired samples of venous blood from 7 infants, median age 5 days, before and after iron-dextran. Post-treatment sera had increased inhibitory effects on leucocyte chemotaxis and markedly reduced bacteriostatic effects agaainst E. coli. The clinical relevance of the effects on chemotaxis is uncertain. The reduction in serum bacteriostasis is similar to that observed in other forms of hyperferraemia not associated with saturation of transferrin, and is a likely cause of the increased susceptibility to infection in vivo. We consider that prophylactic treatment with parenteral iron-dextran is contraindicated in early infancy.

Drug-induced deafness and its treatment.

A comprehensive review is presented of the ototoxic effects of drugs which may damage hearing. These have been classified in tabular form together with the recommended dose, method of administration, and ill-effects upon the inner ear. Special emphasis is laid upon the hazard of prescribing such drugs in certain conditions, including in particular the presence of renal or hepatic insufficiency, and the importance of laboratory assessment of new antibiotics for ototoxicity before undertaking clinical trials.

Chronic granulomatous disease: an inherited disorder of phagocytosis in a Maori ancestry.

Chronic granulomatous disease, in which abnormal susceptibility to infection is caused by an inherited defect in phagocytic cells, has been diagnosed in three brothers. Two brothers had repeated bacterial infections of the skin, superficial lymph nodes and lungs from infancy and died aged 27 months and 13 months. Characteristic suppurating granulomata were found in many organs. The diagnosis was established in both during life, and in the third asymptomatic brother shortly after birth, by studies of phagocytic function which included tests for nitroblue-tetrazolium reduction, hexose monophosphate shunt activity and bactericidal capacity. Their mother and a maternal aunt, both Maoris with no known Caucasian ancestry, were identified as carriers of the presumed sex-linked recessive gene. The clinical features of the disease and the laboratory methods for diagnosis are described.

The cerebral pathways of optokinetic nystagmus: a neuro-anatomical study.

Abnormalities of optokinetic nystagmus are described in a patient with pathologically proven bilateral infarcts in the middle cerebral artery territories. There were no other central nervous system lesions. These abnormalities of eye movement are interpreted as indicating an inhibitory effect of the frontal eye fields upon the occipital lobes.

Benign sinus histiocytosis with massive lymphadenopathy: transient immunological defects in a child with mediastinal involvement.

A 16-month-old boy presented with cervical lymphadenopathy and a mediastinal mass causing tracheal displacement. Treatment of what at first was suspected to be a malignant neoplasm was limited to low-dose irradiation of the mediastinum and biopsy excision of the cervical lymph nodes. There has been no recurrence of disease in the subsequent four years. The pathological features and clinical course correspond to a benign disease first described in 1969 in which there is massive proliferation of histiocytes in lymph node sinuses. No infectious cause was identified. Consistent but eventually reversible defects in lymphocyte response to phytohaemagglutinin and in augmentation of nitro-blue tetrazolium reduction by neutrophils during phagocytosis were demonstrated in the patient and in his monozygous twin. These defects in cellular immune function are believed to be important in the pathogenesis of the histiocytosis.

The significance of optic fixation in tests of vestibular function.

Claims are often made that the electronystagmographic recording of induced nystagmic responses either with eye closure or in darkness enhances the sensitivity of the test. While this may be true of certain parameters it is not true of all and may in fact lead to a reduction in the diagnostic information obtainable with optic fixation upon a target.