Posthyperventilation apnea associated with severe hypoxemia

We studied a 14-year-old girl who suffered fractures of her mandible and tegmen following a fall from a balance beam. Thirteen days after hospitalization, she developed severe, protracted, recurrent episodes of hyperventilation; subsequently, she suffered posthyperventilation apnea, which at times was prolonged and association with severe hypoxemia with an arterial oxygen pressure as low as 25 mm Hg. The patient was treated with added dead space and chlorpromazine hydrochloride (Thorazine). Postulated mechanisms for her disorder are discussed. The importance of close clinical and laboratory observation in similar cases is stressed.     

Selenium biotransformations in an insect ecosystem: effects of insects on phytoremediation

Phytoremediation of selenium-contaminated soils may be influenced by higher trophic levels including insects. We examined how selenium affects the behavior, survival, and development of the wasp parasitoid Cotesia marginiventris, parasitizing its natural host, the beet armyworm Spodoptera exigua, feeding on alfalfa, Medicago sativa, irrigated with water containing selenate. X-ray absorption spectroscopy was used to quantify the selenium chemical forms in each trophic level. Alfalfa partially transformed selenate to organoselenium. S. exigua contained only organoselenium, both directly absorbed from M. sativa and transformed from selenate. C. marginiventris cocoons collected shortly after larval emergence contained only organoselenium derived from the host. The surprising finding of trimethylselenonium-like species in adult parasitoids and the cocoons from which they emerged suggests that adults and pharates can detoxify excess selenium through methylation and volatilization. Adult parasitoids do not discriminate against selenium-containing alfalfa, even though alfalfa generates selenium volatiles. Parasitoids raised on selenium-fed larvae emerged later and pupae weighed less than their selenium-free counterparts. We conclude therefore that C. marginiventris can be used to control S. exigua damage to M. sativa being used to remove selenium from soils. Moreover, the presence of such insects may improve phytoremediation by increasing biotransformation of inorganic selenium and release of volatile selenium species.     

Diaphragm activation with intramuscular stimulation in dogs

We studied in 10 supine anesthetized dogs diaphragm contraction produced by electrical activation with intramuscular electrodes surgically implanted in the ventral surface of the diaphragm and compared this with activation of the ipsilateral phrenic nerve (C5, 6, and 7) before it entered the thorax. Repetitive 40-Hz pulse trains with supramaximal current stimulus were used after hyperventilation of the animals to apnea. A single intramuscular electrode within 1 to 2 cm of the site of phrenic nerve entry into the diaphragm produced a mean transdiaphragmatic pressure of 12.0 cm H2O +/- 0.97 SE and mean tidal volume of 0.27 L +/- 0.04 SE. Mean values observed with phrenic nerve stimulation were not statistically different, and both electrode systems produced equivalent outward abdominal motion and upper rib cage paradox, as monitored by inductive plethysmography. There was no difference in gas exchange during stimulation with a single hemidiaphragm electrode and mechanical ventilation compared at the same tidal volume and respiratory rate. Blockade of neuromuscular transmission with curare eliminated intramuscular and phrenic nerve stimulation proportionately, suggesting that activation of the diaphragm is dependent in both cases on the phrenic nerve. This technique does not entail manipulation of the phrenic nerve and may have clinical application as an alternative technique for diaphragm pacing.     

Biosynthesis of scarab beetle pheromones

Chemical communication in scarab beetles (Coleoptera: Scarabaeidae) is achieved with a wide variety of pheromones, but one typical structure is the gamma-lactone having a long unsaturated hydrocarbon chain. Several species utilize (R, Z)-5-(-)-(oct-1-enyl)-oxacyclopentan-2-one (buibuilactone), (R, Z)-5-(-)-(dec-1-enyl)-oxacyclopentan-2-one and (S, Z)-5-(+)-(dec-1-enyl)-oxacyclopentan-2-one [(R)-japonilure and (S)-japonilure]. Using deuterated precursors, we have demonstrated that these compounds are biosynthesized from fatty acids. (9, 10-d4)-Palmitic acid, (9,10-d4)-stearic acid, (9,10-d2)-palmitoleic acid, (9,10-d2)-oleic acid, (9,10-d2)-8-hydroxypalmitoleic acid and (9,10-d2)-8-hydroxyoleic acid were readily incorporated by female Anomala cuprea into the pheromone molecules, while (Z)-(5, 6-d2)-5-dodecenoic acid and (Z)-(5,6-d2)-5-tetradecenoic acid were not. Therefore, the reaction pathway starts from saturated fatty acids, involves their desaturation, followed by 8-hydroxylation, chain shortening and cyclization. The products obtained from racemic (9,10-d2)-8-hydroxypalmitoleic acid and (9,10-d2)-8-hydroxyoleic acid were also racemic, implying that the steps following hydroxylation were not stereospecific. Perdeuterated palmitic acid was applied to disclose the mechanism of the unique hydroxylation reaction. Retention of all deuterium atoms implied that this reaction was a direct process mediated by a specific fatty acid hydroxylase, and preceding desaturation or epoxidation was not involved.     

Physical and functional interactions between the herpes simplex virus UL15 and UL28 DNA cleavage and packaging proteins

Herpes simplex virus (HSV) DNA is cleaved from concatemers and packaged into capsids in infected cell nuclei. This process requires seven viral proteins, including UL15 and UL28. UL15 expressed alone displays a nuclear localization, while UL28 remains cytoplasmic. Coexpression with UL15 enables UL28 to enter nuclei, suggesting an interaction between the two proteins. Additionally, UL28 copurified with UL15 from HSV-infected cells after ion-exchange and DNA affinity chromatography, and the complex sedimented as a 1:1 heterodimer upon sucrose gradient centrifugation. These findings are evidence of a physical interaction of UL15 and UL28 and a functional role for UL15 in directing UL28 to the nucleus.     

A survey of seroprevalence of human papillomavirus types 16, 18 and 33 among children

The importance and natural history of HPV infections in childhood is incompletely understood. We performed a survey for presence of serum antibodies to HPV capsids among 1031 children aged 0 to 13 years, resident in Stockholm, Sweden. The HPV seroprevalence among these children was 3.0% for HPV16, 0.6% for HPV18 and 2.7% for HPV33. By comparison, among simultaneously analyzed positive control panels comprising women with CIN or healthy women with type-specific cervical HPV DNA, seroprevalence of HPV 16, 18 and 33 was 69%, 58% and 63% respectively. The results suggest that HPV infection in childhood is not common.