The effect of feeding immature Karoo paralysis ticksIxodes rubicundus (Acari: Ixodidae) on the metabolic rate of the rock elephant shrew

The effect of feeding immature Karoo paralysis ticks (Ixodes rubicundus) on the resting metabolic rate (RMR) of their principal natural host, the rock elephant shrew (Elephantulus myurus), was investigated under laboratory conditions. The elephant shrews were artificially infested with numbers of ticks simulating natural burdens. The RMR of the elephant shrews was quantified by measuring the oxygen consumption in an open through-flow system. The RMR of hosts infested only with larvae did not differ from that of the control group. Those infested with nymphs, or nymphs and larvae, had significantly lower RMR's compared to the control animals. There were no signs of paralysis in any of the infested hosts.     

Development of an anti-Aβ monoclonal antibody for in vivo imaging of amyloid angiopathy in Alzheimer's disease

We evaluated the efficacy of murine monoclonal antibodies (MAbs) targeted to the Aβ amyloid of Alzheimer's disease for development of procedures for the in vivo identification of amyloid angiopathy (AA). MAbs to Aβ were prepared and screened for effectiveness in visualizing AA and neuritic plaques in postmortem AD brain sections. They were assessed again after enzymatic cleavage to produce Fab fragments and after labeling with technetium-99m (^99mTc) using a diamide dimercaptide ligand system. Modified and radiolabeled Fab fragments retained activity and specificity toward amyloid-laden blood vessels and neuritic plaques. A highly specific murine MAb, 10H3, was identified and characterized that fulfills criteria necessary for the development of an in vivo diagnostic imaging agent. Toxicity studies in rats showed the MAb to be safe. Biodistribution studies in mice demonstrated desirable properties for use as an imaging agent. Expansion and adaptation of these strategies may provide the methods and materials for the noninvasive analysis of AA in living patients, and permit assessment of the contribution of AA to the clinical and pathological features of AD.     

Transformation of steroids by fungal spores

Summary The steroid-hydroxylating activity during spore swelling prior to germination (I), during germ tube formation (II) and during branching of the growth hyphae (III) is two to five times that of the mycelium (IV) and control spores. The increased steroid-transforming activity is not correlated with the overall degradation of free amino acid pools but only with that of alanine, glutamate, arginine and proline. A higher ratio NADPH:(NADP⁺+NADPH) was observed in development phases I, II, and III, which indicates a possible role of alanine, glutamate and other amino acids decomposed via glutamate, in NADPH generation and steroid-hydroxylase activation.     

Scanning electron microscopic visualization of a microexudate prepared by the release of cells by urea

The scanning electron microscope (SEM) was used to examine the residue remaining after human fibroblasts, permitted to attach to plastic dishes in the absence of serum, were removed with buffered 1 M urea. The ‘urea carpet’ is entirely different from the “substrate-attached material” (SAM) of Culp [4, 5, 6] in that it contains no “footpad” material. Furthermore, the SEM pictures clearly indicate that urea carpet stimulates the adhesion and spreading of newly added fibroblasts.     

A novel priming system for conjugal synthesis of an IncI alpha plasmid in recipients.

Summary Synthesis of DNA complementary to the transferred strand of an IncI plasmid has been shown previously to require DNA polymerase III. The possible involvement of the two defined priming proteins of Escherichia coli K12, RNA polymerase and primase, in initiating this conjugal DNA synthesis has been examined. Primase was inactivated using temperature-sensitive dnaG3 mutants and RNA polymerase was inhibited using rifampicin. When these two proteins were simultaneously inactivated in both parental strains, the average recipient synthesised at least one single-stranded equivalent of R144drd-3 before the rifampicin-treated donors lost the ability to transmit DNA. It is proposed that the product of a plasmid transfer gene is responsible for initiating this DNA synthesis in recipients. The results imply that this protein is supplied by the donors.     

Factors affecting ethylene production by some plant pathogenic bacteria

Summary Methionine, up to 10^–3 M, added to a basal medium enhanced bacterial ethylene production in 14 of the 20 bacteria tested. The effects of substrate, cofactors, light, and temperature on ethylene production byPseudomonas solanacearum #25 revealed that the greatest effect occurred when 10^–5 M methionine and 10^–4 M FMN were combined, from which 4.10l/l of ethylene were produced. Higher levels of methionine resulted in production of high levels of non-enzymically produced ethylene and death of the bacteria. This non-enzymic production of ethylene was eliminated in the dark. Copper had no effect upon ethylene production. Twenty-nine and 35°C were inhibitory, whereas 19°C appeared to be near optimum for ethylene production.Pseudomonas solanacaerum #25 and some other bacteria are capable of ethylene production and methionine and FMN enhance this production.This work was supported by the Fred C. Gloeckner Foundation and the University of Minnesota Graduate School Grant in Aid #496-0307-4909-02.     

The structure of a triterpenoid ketol from Cetraria nivalis

A triterpenoid ketol isolated from a Norwegian species of Cetraria nivalis is identified as 22α-hydroxy-stictan-3-one, a triterpenoid present in some Pseudocyphellaria lichens.     

Disease and illness Distinctions between professional and popular ideas of sickness

The dysfunctional consequences of the Cartesian dichotomy have been enhanced by the power of biomedical technology. Technical virtuosity reifies the mechanical model and widens the gap between what patients seek and doctors provide.Patients suffer illnesses; doctors diagnose and treat diseases. Illnesses are experiences of discontinuities in states of being and perceived role performances. Diseases, in the scientific paradigm of modern medicine, are abnormalities in the function and/or structure of body organs and systems. Traditional healers also redefine illness as disease: because they share symbols and metaphors consonant with lay beliefs, their healing rituals are more responsive to the psychosocial context of illness.Psychiatric disorders offer an illuminating perspective on the basic medical dilemma. The paradigms for psychiatric practice include multiple and ostensibly contradictory models: organic, psychodynamic, behavioural and social. This melange of concepts stems from the fact that the fundamental manifestations of psychosis are disordered behaviours. The psychotic patient remains a person; his self-concept and relationships with others are central to the therapeutic encounter, whatever pharmacological adjuncts are employed.The same truths hold for all patients. The social matrix determines when and how the patient seeks what kind of help, his compliance with the recommended regimen and, to a significant extent, the functional outcome. When physicians dismiss illness because ascertainable disease is absent, they fail to meet their socially assigned responsibility. It is essential to reintegrate scientific and social concepts of disease and illness as a basis for a functional system of medical research and care.Harvard Medical School     

Magnetic resonance studies of eukaryotic cells. III. Spin labeled fatty acids in the plasma membrane

XC Sarcoma, Vero and Aedes aegypti plasma membranes have been studied in viable cells and in purified membrane of XC Sarcoma cells by the spin label method. The temperature dependence of the order parameter of fatty acid spin labels is found to be linear in all three cells and membrane and shows no evidence of a lipid phase transition. The order parameter of the fatty acid labels substituted at the 5-position is shown to increase as a function of the cholesterol: phospholipid molar ratio in cells that have been studied to date. Cells attached to their growing surface are studied for the first time by electron paramagnetic resonance spectroscopy (EPR). The resulting spectra are anisotropic due to the non-spherical shape of the cells and show that these labels orient preferentially perpendicular to the cell surface. The viscosity of the extracted XC cell membrane is estimated to be 2.5 P from rotational correlation time measurements of the spin label 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO).