Time-resolved resonance raman spectroscopy of hemoglobin derivatives: heme structure changes in 7 nanoseconds.

Resonance Raman spectra of oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and the corresponding myoglobin derivatives have been obtained with 7-nanosecond laser pulses at 531.8 nanometers. The results suggest that no transient constraint of the heme group by the globin structure occurs on this time scale, and thus establish a temporal sequence for the early events that may participate in the stereochemical trigger mechanism of hemoglobin cooperativity.

Ultrafast infrared spectroscopy.

Recent advances in ultrafast infrared spectroscopy are described, including experimental details and fundamental limitations. The utility of this technique is illustrated with two recent examples.

Daily activity patterns of two co-occurring tropical satyrine butterflies.

Adult males and females of many insect species are expected to adjust their daily activity pattern in order to avoid stressful climatic conditions and increase the chances to encounter sexual partners. Using scan sampling methods associated with focal individual observations it was found that two satyrine butterflies of similar size and morphology, Hermeuptychia hermes (Fabricius) (Leptidoptera: Nymphalidae) and Paryphthimoides phronius (Godart), show completely different daily activity patterns on forest edges in southeastern Brazil. Hermeuptychia hermes presents one abundance peak in the morning and another in the late afternoon, while P. phronius abundance peaks in the mid-day, remaining stable until 1700 h. This difference is probably due to the occurrence of territorial behavior in the later species. The beginning of territorial defense by P. phronius males coincided with the time of new-born female activity. However, newly hatched females were not sexually receptive. The afternoon territoriality in male P. phronius may be in part related to mate acquisition. However, why the abundance of H. hermes decreases when the abundance of P. phronius increases is less clear.

Geographic variation in resource dominance-discovery in Brazilian ant communities.

A predictive framework for the ecology of species invasions requires that we learn what limits successful invaders in their native range. The red imported fire ant (Solenopsis invicta) is invasive in the United States, Puerto Rico, Australia, New Zealand, and China. Solenopsis invicta appears to be a superior competitor in its introduced range, where it can cause the local extirpation of native species, but little is known about its competitive ability in its native range in South America. Here we examine the competitive ability of S. invicta for food resources in three widely separated Brazilian ant communities. Each of these communities contains 20-40 ant species, 8-10 of which were common and frequently interacted with S. invicta. S. invicta at all three sites was attacked by several species-specific phorid parasitoids, and at one site, two other species were attacked by their own specialized parasitoids. We examined interactions in these local communities for evidence that trade-offs among ant species between resource dominance and resource discovery, and between resource dominance and parasitoid vulnerability facilitate local coexistence. The trade-off between resource dominance and resource discovery was strong and significant only at Santa Genebra, where parasitoids had no effect on the outcome of confrontations at resources. At Bonito, parasitoids significantly reduced the ability of S. invicta, which was the top-ranked behavioral dominant, from defending and usurping food resources from subordinate species. In the Pantanal, S. invicta ranked behind three other ant species in a linear hierarchy of behavioral dominance, and lost the majority of its interactions with a fourth more subordinate species, Paratrechina fulva, another invasive species. Parasitoids of S. invicta were uncommon in the Pantanal, and did not affect its low position in the hierarchy relative to the other two sites. Parasitoids, however, did affect the ability of Linepithema angulatum, the top-ranked behavioral dominant in this community, from defending and usurping resources from behavioral subordinates. These results indicate that both interspecific competition and trait-mediated indirect effects of phorid parasitoids affect the ecological success of the red imported fire ant in its native range, but that the relative importance of these factors varies geographically.

Biotic interactions of mites, plants and leaf domatia.

Leaf domatia, minute structures that typically house mites and other small arthropods, are produced by an impressive number of plants; however, their role in mediating plant-mite mutualism has only recently been elucidated. New evidence indicates that domatia function primarily as refuges for beneficial mites against predators. The presence of domatia therefore results in more beneficial mites on leaves, fewer pathogen attacks and reduced leaf herbivory. Unexpectedly, herbivorous mites are specialized domatia inhabitants of some plants. By providing refuges for herbivores, however, domatia may stabilize interactions between predator and their mite prey and thereby reduce the chances of herbivore outbreaks. Understanding the ecological mechanisms that promote beneficial interactions between mites and plants could have important implications for pest management.

Resonance Raman studies of Rieske-type proteins.

Resonance Raman (RR) spectra are reported for the [2Fe-2S] Rieske protein from Thermus thermophilus (TRP) and phthalate dioxygenase from Pseudomonas cepacia (PDO) as a function of pH and excitation wavelength. Depolarization ratio measurements are presented for the RR spectra of spinach ferredoxin (SFD), TRP, and PDO at 74 K. By comparison with previously published RR spectra of SFD, we suggest reasonable assignments for the spectra of TRP and PDO. The spectra of PDO exhibit virtually no pH dependence, while significant changes are observed in TRP spectra upon raising the pH from 7.3 to 10.1. One band near 270 cm-1, which consists of components at 266 cm-1 and 274 cm-1, is attributed to Fe(III)-N(His) stretching motions. We suggest that these two components arise from conformers having a protonated-hydrogen-bonded imidazole (266 cm-1) and deprotonated-hydrogen-bonded imidazolate (274 cm-1) coordinated to the Fe/S cluster and that the relative populations of the two species are pH-dependent; a simple structural model is proposed to account for this behavior in the respiratory-type Rieske proteins. In addition, we have identified RR peaks associated with the bridging and terminal sulfur atoms of the Fe-S-N cluster. The RR excitation profiles of peaks associated with these atoms are indistinguishable from each other in TRP (pH 7.3) and PDO and differ greatly from those of [2Fe-2S] ferrodoxins. The profiles are bimodal with maxima near 490 nm and > approx. 550 nm. By contrast, bands associated with the Fe-N stretch show a somewhat different enhancement profile. Upon reduction, RR peaks assigned to Fe-N vibrations are no longer observed, with the resulting spectrum being remarkably similar to that reported for reduced adrenodoxin. This indicates that only modes associated with Fe-S bonds are observed and supports the idea that the reducing electron resides on the iron atom coordinated to the two histidine residues. Taken as a whole, the data are consistent with an St2FeSb2Fe[N(His)]t2 structure for the Rieske-type cluster.

Deleterious effects of criminal victimization on women's health and medical utilization.

The long-term consequences of criminal victimization on physical health were examined among 390 adult women (74 nonvictims and 316 victims of crime). Data included health status self-ratings and objective service utilization. Findings indicated that severely victimized women, compared with nonvictims, reported more distress and less well-being, made physician visits twice as frequently in the index year, and had outpatient costs that were 2.5 times greater. Criminal victimization severity was the most powerful predictor of physician visits and outpatient costs. Utilization data across 5 years preceding and following crime were obtained from 15 rape victims, 26 physical assault victims, and 27 noncontact crime victims and were compared with five continuous years of utilization among 26 nonvictims. Victims' physician visits increased 15% to 24% during the year of the crime compared with less than 2% change among nonvictims. We conclude that these long-term deleterious effects suggest that criminally victimized women's needs for medical treatment transcend the traditional focus on emergency care and forensic evaluation.

Sequence analysis of mutA and mutM genes involved in the biosynthesis of the lantibiotic mutacin II in Streptococcus mutans.

Streptococcus mutans, along with many other gram-positive bacteria produce small antibacterial peptides called bacteriocins. Bacteriocins elaborated by S. mutans, termed mutacins, may provide a selective force necessary for initial or sustained colonization in dental plaque by this major dental pathogen. Previously, we purified and characterized mutacin II, the first lantibiotic found in S. mutans. Specific oligonucleotides designed according to the N-terminal amino acid sequence permitted amplification of 0.7 kb upstream and 2.1 kb downstream of the N-terminus, using single-specific-primer PCR (SSP-PCR). The gene encoding the mutacin II prepeptide, mutA, was subsequently cloned and sequenced. The complete prepeptide consists of 53 amino acids, including the 26 amino acid amphipathic leader peptide with the Gly(-2)-Gly(-1) sequence at the processing site. The prepeptide showed similarity to the lantibiotics lacticin 481, variacin, salivaricin and streptococcin A-FF22. A 3 kb open reading frame immediately downstream of mutA, denoted mutM, showed sequence similarities to LCNDR2 from Lactococcus lactis. By analogy, mutM is probably involved in post-translational modification of the mutacin prepeptide. Gene disruption with an insertional vector pVA891 showed that intact copies of mutA and mutM are required for production of mutacin II.

Bound water in the proton translocation mechanism of the haem-copper oxidases.

We address the molecular mechanism by which the haem-copper oxidases translocate protons. Reduction of O2 to water takes place at a haem iron-copper (CuB) centre, and protons enter from one side of the membrane through a 'channel' structure in the enzyme. Statistical-mechanical calculations predict bound water molecules within this channel, and mutagenesis experiments show that breaking this water structure impedes proton translocation. Hydrogen-bonded water molecules connect the channel further via a conserved glutamic acid residue to a histidine ligand of CuB. The glutamic acid side chain may have to move during proton transfer because proton translocation is abolished if it is forced to interact with a nearby lysine or arginine. Perturbing the CuB ligand structure shifts an infrared mode that may be ascribed to the O-H stretch of bound water. This is sensitive to mutations of the glutamic acid, supporting its connectivity to the histidine. These results suggest key roles of bound water, the glutamic acid and the histidine copper ligand in the mechanism of proton translocation.

Spectra of cells in flow cytometry using a vidicon detector.

A TV type vidicon detector was interfaced to a flow cytometer (FCM) to obtain spectra of fluorophores in cells during flow. The normal operations of the FCM are undisturbed. A spectrograph spreads 320 nm of the fluorophore fluorescence emission across the 500 channels of the detector. Spectra of fluorescamine (a surface labeling agent) and of propidium iodide (a nuclear stain) were obtained from Balb 3T3 cells, and the chlorophyll and phycobilin peaks were resolved from flowing blue-green algae in the FCM. Under typical flow conditions, operation of the vidicon in the continuous mode gives for these fluorophores a S/N of several hundred to one in approximately 3 sec. The vidicon was also gated to obtain spectra of single cells and of cells in selected portions of the cell cycle. For example, the spectrum of fluorescamine was obtained from cells in the G1 phase of the growth cycle by using as a gate trigger the FCM discriminator output derived from the propidium iodide signal.

Symptom perception by nonpsychiatric physicians in evaluating for depression.

A questionnaire was constructed and used to assess the perception of symptoms of a depressive disorder by nonpsychiatric physicians in patient evaluations. Results showed that respondents consistently perceived depression as resulting from psychological rather than biological factors. It is suggested that such perception on the part of physicians may hinder consolidation of a patient's symptom complex with the degree of certainty necessary for a diagnostic consideration of depressive disorder.

MR findings in oculocerebrorenal syndrome.

Oculocerebrorenal syndrome is an X-linked recessive disorder characterized by congenital ocular abnormalities, mental retardation, renal disease, and metabolic bone disease. We report a case of oculocerebrorenal syndrome and, using T1-, proton density-, and T2-weighted imaging sequences, are able to characterize two distinct white matter abnormalities: one lesion is punctate and has signal characteristics that parallel that of cerebrospinal fluid; a second lesion, found in association with the first, consists of patchy white matter abnormalities that are hypointense on T1-weighted images but hyperintense on proton density- and T2-weighted images.

Hyperprolactinemia: an unusual manifestation of suprasellar cystic lesions.

Two patients with suprasellar cysts and hyperprolactinemia are described. These lesions were diagnosed by CT metrizamide cisternography. Suprasellar cysts are a rare cause of pathologic hyperprolactinemia, which most commonly results from pituitary adenomas. Tissue diagnosis revealed suprasellar arachnoid cysts in the first patient and Rathke's cleft cyst in the second. The differential diagnosis of suprasellar cysts is presented, and distinguishing radiographic characteristics are discussed.

Relation of criminal victimization to health perceptions among women medical patients.

The relation of criminal victimization to health perceptions (self-rated current health) was determined among women health maintenance organization patients. Data were survey responses from 2,291 women (45% response rate), 57% of whom had experienced crime. Reliability was evaluated by assessing 241 respondents both by survey and by interview. Data were analyzed by hierarchical multiple regression, which indicated that criminal victimization was an important predictor of health perceptions even after accounting for the contributions of demographics and other stressful life events with known links to illness. Validity was supported because medical care was actually sought by 92% of crime victims during the 1st year following the crime and by 100% during the 2nd year. Conclusions included the following: (a) Crime victimization history is relevant to health status assessment, and (b) primary care medical populations are an important locus from which crime victims could be identified and their treatment options considered.

Flow-flash, time-resolved resonance Raman spectroscopy of the oxidation of reduced and of mixed valence cytochrome oxidase by dioxygen.

Time-resolved resonance Raman spectroscopy has been used to study the reduction of oxygen by both reduced and mixed valence cytochrome oxidase. Laser flash photodissociation of CO from the carbon monoxy complex of the enzyme, after this species had been rapidly mixed with oxygenated buffer, was used to initiate the reaction for both forms of the enzyme. The CO photolysis product of the mixed valence enzyme contains cytochrome a3+ and cytochrome a3(2+) in its unligated form. This species reacts with O2 in the first few microseconds to form a photolabile intermediate which has Raman frequencies characteristic of oxygenated heme. This indicates that an oxyhemoglobinlike complex of oxygen with a3(2+) is the precursor to oxygen reduction. A similar intermediate is detected in the fully reduced enzyme reaction. In the mixed valence oxidase system, the oxy intermediate is replaced by a nonphotolabile species in which a3 is oxidized with t1/2 approximately equal to 200 musec. These results demonstrate the feasibility of applying time-resolved vibrational techniques to irreversible electron transfer reactions and, in particular, elucidate some of the transient species in the cytochrome oxidase/O2 system.

Maxillary sinus hypoplasia: classification and description of associated uncinate process hypoplasia.

Maxillary sinus hypoplasia is an anomaly of the paranasal sinuses occasionally encountered by otolaryngologists. Although this entity has been previously reported, an association between maxillary sinus hypoplasia and anomalies of other paranasal sinus structures, such as the uncinate process, has not yet been described. Additionally, the literature lacks a system by which the various types of maxillary sinus hypoplasia can be classified using computerized tomographic (CT) imaging. Two hundred and two consecutive coronal sinus computerized tomographic scans from patients undergoing evaluation at our institution were analyzed to determine the prevalence of MSH and associated paranasal sinus anomalies. The overall prevalence of maxillary sinus hypoplasia was 10.4%. Three distinct patterns of hypoplasia were evident. Type I, characterized by a normal uncinate process, a well-defined infundibular passage, and mild sinus hypoplasia, occurred in 14 patients (6.9%). Type II, characterized by absence or hypoplasia of the uncinate process, an ill-defined infundibular passage, and soft-tissue density opacification of a significantly hypoplastic sinus occurred in 6 patients (3.0%). Type III, characterized by absence of the uncinate process and a profoundly hypoplastic, cleft-like sinus, occurred in 1 patient (0.5%). Recognition of associated anomalies of the uncinate process in patients with maxillary sinus hypoplasia undergoing sinus surgery is of utmost clinical significance because the uncinate process serves as a key landmark during functional endoscopic sinus surgery. Failure to recognize hypoplasia or absence of the uncinate process could lead to inadvertent intraoperative damage to the adjacent medial orbital wall.

Direct angioplasty of the basilar artery in baboons.

The lower portion of the basilar artery is a site of significant disease, both aneurysmal and stenotic, but has been considered inaccessible via traditional surgical approaches. A baboon model was used to evaluate the feasibility of a direct surgical reconstruction via a transoral-transclival approach, utilizing temporary occlusion of the basilar artery. An arteriotomy was performed and either repaired primarily or a venous patch graft was sutured in place. All animals survived the surgery; one suffered fatal postoperative upper airway obstruction, but the other four were neurologically intact at the time of death. Patency at the site of repair was confirmed both angiographically and histologically. We conclude that temporary clamping in conjunction with direct reconstruction of the basilar artery is feasible in this primate model. Future studies will focus on further applications of this technique.

Non-nodal neck masses.

Planar imaging has made significant contributions to the evaluation of patients with non-nodal neck masses. The clinical history, physical examination, and imaging characteristics of these lesions are often complimentary. Yet, planar imaging much more accurately defines the size, location, and extent of these lesions than is revealed on physical examination. The CT and MR characteristics are often sufficiently specific to arrive at the correct preoperative diagnosis in these patients. We present the classical radiographic and clinical features of several non-nodal neck masses.

Posterior fossa neoplasms: multiplanar imaging.

Multiplanar imaging capabilities and increased tissue contrast inherent to MR permit inimitable evaluation of the normal and abnormal structures of the posterior fossa. A review of common posterior fossa neoplasms in adults and children is presented with emphasis on the MR characteristics.