Transition from susceptible-infected to susceptible-infected-recovered dynamics in a susceptible-cleric-zombie-recovered active matter model.

The susceptible-infected (SI) and susceptible-infected-recovered (SIR) models provide two distinct representations of epidemic evolution, distinguished by whether or not the number of susceptibles always drops to zero at long times. Here we introduce a new active matter epidemic model, the "susceptible-cleric-zombie-recovered" (SCZR) model, in which spontaneous recovery is absent but zombies can recover with probability γ via interaction with a cleric. Upon colliding with a zombie, both susceptibles and clerics enter the zombie state with probability ß and α, respectively. By changing the initial fraction of clerics or their healing ability rate γ, we can tune the SCZR model between SI dynamics, in which no susceptibles or clerics remain at long times, and SIR dynamics, in which a finite number of clerics and susceptibles survive at long times. The model is relevant to certain real world diseases such as HIV where spontaneous recovery is impossible but where medical interventions by a limited number of caregivers can reduce or eliminate the spread of infection.

Using active matter to introduce spatial heterogeneity to the susceptible infected recovered model of epidemic spreading.

The widely used susceptible-infected-recovered (S-I-R) epidemic model assumes a uniform, well-mixed population, and incorporation of spatial heterogeneities remains a major challenge. Understanding failures of the mixing assumption is important for designing effective disease mitigation approaches. We combine a run-and-tumble self-propelled active matter system with an S-I-R model to capture the effects of spatial disorder. Working in the motility-induced phase separation regime both with and without quenched disorder, we find two epidemic regimes. For low transmissibility, quenched disorder lowers the frequency of epidemics and increases their average duration. For high transmissibility, the epidemic spreads as a front and the epidemic curves are less sensitive to quenched disorder; however, within this regime it is possible for quenched disorder to enhance the contagion by creating regions of higher particle densities. We discuss how this system could be realized using artificial swimmers with mobile optical traps operated on a feedback loop.

Active matter shepherding and clustering in inhomogeneous environments.

We consider a mixture of active and passive run-and-tumble disks in an inhomogeneous environment where only half of the sample contains quenched disorder or pinning. The disks are initialized in a fully mixed state of uniform density. We identify several distinct dynamical phases as a function of motor force and pinning density. At high pinning densities and high motor forces, there is a two-step process initiated by a rapid accumulation of both active and passive disks in the pinned region, which produces a large density gradient in the system. This is followed by a slower species phase separation process where the inactive disks are shepherded by the active disks into the pin-free region, forming a nonclustered fluid and producing a more uniform density with species phase separation. For higher pinning densities and low motor forces, the dynamics becomes very slow and the system maintains a strong density gradient. For weaker pinning and large motor forces, a floating clustered state appears, and the time-averaged density of the system is uniform. We illustrate the appearance of these phases in a dynamic phase diagram.

Nicotinic receptors and cognition in Parkinson's Disease: the importance of neuronal synchrony.

Parkinson's Disease (PD) is associated with cognitive deficits. The earliest impairment is evident for executive abilities, visuospatial orientation and memory. Dopamine deficiency is unlikely to be singly responsible for all cognitive changes in PD. Acetyl-choline has an essential role in cognition, thus cholinergic transmission may have an important role in non-dopaminergic cognitive changes. If so, some cognitive defects could possibly be treated with choline-esterase inhibitors. A concern is the potential negative motor effect of cholinergic medication in PD. Surprisingly, these are reported only in a few patients studied. Establishing the relationship between select cognitive deficits and nicotinic neurotransmission may lay the foundation for rational pharmacotherapy of cognitive dysfunction in PD. We summarize anatomical, physiological and pharmacological aspects of nicotinic receptor function. The focus is on those nicotine receptor dependent cognitive dysfunctions which are likely to contribute to motor impairment. Lastly, we discuss hypotheses concerning cholinergic involvement in neuronal synchrony and sensorimotor integration in PD.

Characterization of chemical meningitis after neurological surgery.

We reviewed the records of 70 consecutive adult patients with meningitis after a neurosurgical procedure, to determine the characteristics that might help to distinguish a sterile postoperative chemical meningitis from bacterial infection. The spinal fluid profiles in bacterial and chemical meningitis are similar. The exceptions are that a spinal fluid white blood cell count > 7500/microL (7500 x 10(6)/L) and a glucose level of < 10 mg/dL were not found in any case of chemical meningitis. The clinical setting and clinical manifestations were distinct enough that no antibiotic was administered after lumbar puncture to 30 (43%) of the 70 patients with postoperative meningitis. Chemical meningitis was infrequent after surgery involving the spine and sinuses. Patients with chemical meningitis did not have purulent wound drainage or significant wound erythema or tenderness, coma, new focal neurological findings, or onset of a new seizure disorder. They rarely had temperatures > 39.4 degrees C or cerebrospinal fluid rhinorrhea or otorrhea.

Prostanoid synthesis in the cerebral blood vessels of asphyxiated piglets.

The aim of this study was to examine the effects of asphyxia-reventilation and hyperoxia on the cerebral blood perfusion and prostanoid production of the brain arteries and microvessels in piglets. After 10 min of asphyxia, animals were ventilated with room air, or with 100% O2. Following 4 hours of recovery, the brains were perfused, cerebral arteries were removed and microvessels were isolated from the cortex. The microvessels and the arteries were incubated with 1-14C-arachidonic acid, and the 1-14C-prostanoids were then separated by means of overpressure thin-layer chromatography and were quantitatively determined. Under control conditions, the synthesis of dilatory prostanoids dominated the arachidonate cascade both in the microvessels and in the arteries. Asphyxia and reventilation with room air did not modify the prostanoid production. O2 ventilation greatly affected the prostanoid synthesis of the microvessels, with an enhancement of PGD2 up to 247 +/- 27%. In the arteries, the production of PGI2 and of PGE2 was elevated to 272 +/- 15% and to 148 +/- 13%, respectively. These findings indicate that O2 ventilation after asphyxia substantially increases the extent of prostanoid synthesis in the cerebral blood vessels.

A case of Ureaplasma urealyticum septic arthritis in a patient with hypogammaglobulinemia.

Patients with hypogammaglobulinemia have an increased susceptibility to certain infections. We describe the case of a patient with common variable hypogammaglobulinemia for whom the diagnosis of destructive monoarticular arthritis caused by Ureaplasma urealyticum was established after two nondiagnostic open biopsies had been performed. Mycoplasmal infection may involve a joint in hypogammaglobulinemic patients without causing macroscopic purulence in the joint. Histological examination of the bone may be helpful in the differentiation of an infectious process from the rheumatoidlike arthritis that occurs in such patients. Culture of involved bone in addition to synovium or synovial fluid may also be helpful in establishing the diagnosis.

Comparison of electronic and viability counting methods for determination of postantibiotic effect of oxacillin on Staphylococcus aureus.

The postantibiotic effect of oxacillin on Staphylococcus aureus ATCC 6538P was determined under different test conditions by reference (viability counting) and semiautomated (electronic counting) methods. Differences in durations of the postantibiotic effect obtained with the two counting methods were not statistically significant. The semiautomated method provided a more rapid and convenient alternative to viability counting.

Chronic fatigue syndrome and the diagnostic utility of antibody to Epstein-Barr virus early antigen.

Antibody to Epstein-Barr virus (EBV) early antigen has been said to be the most specific indicator of symptomatic chronic EBV infection. We studied the clinical utility of this serologic test in the evaluation of patients with chronic fatigue. Thirty patients with chronic fatigue and highly elevated titers of antibody to early antigen (greater than or equal to 1:160) were compared with 30 age- and sex-matched controls with no antibody to early antigen. There were no significant differences noted between patients and controls at the initial evaluation (symptoms, physical examination, laboratory data). Follow-up information, available for 15 matched pairs, showed no differences in outcome between patients and controls. We conclude that the antibody to EBV early antigen is not helpful in the clinical evaluation of patients with chronic fatigue.

Acute fulminating fatal leukoencephalopathy as the only manifestation of human immunodeficiency virus infection.

A case of acute human immunodeficiency virus (HIV) infection manifested by a rapidly fulminating, necrotizing, demyelinating encephalopathy that led to brain death in 5 days is reported. Autopsy demonstrated predominant white matter lesions, acute neuronal damage, and scanty cellular response. Cultures of cerebrospinal fluid were positive for HIV, suggesting an acute infection.

First report of subcutaneous phaeohyphomycosis of the foot caused by Phoma minutella.

Phoma minutella, a dematiaceous hyphomycete, was isolated to the exclusion of all other fungi from a subcutaneous inflammatory process on the foot of a farmer undergoing corticosteroid therapy for myasthenia gravis. Isolation was achieved on several nutrient media. Examination of stained smears and sections revealed dematiaceous fungal elements consistent with the mold. This is the first reported association of P. minutella with a human infection and only the second reported case involving a Phoma sp. as the etiologic agent of a subcutaneous infection.

Infective endocarditis: a challenging disease.

Enhanced clinical awareness of infective endocarditis, along with improved microbiologic methodology and more aggressive surgical intervention, has favorably influenced the outcome of the disease. The evolving nature of infective endocarditis over the past decade is described, as are the changing epidemiologic factors, microbiologic techniques, and echocardiographic contributions in the clinical management of patients with infective endocarditis.

Virologic studies in a case of transfusion-associated AIDS.

PIP: The authors present the case of a 60-year old woman who developed acquired immunedeficiency syndrome (AIDS) 43 months after a blood transfusion. The blood donor was identified as a sexually active homosexual man who frequently used intravenous drugs. Although he was asymptomatic, physical examination revealed generalized lymphadenopathy of cervical, axillary, and inguinal areas. 47 months after his blood donation, the donor underwent lymph node biopsy which revealed follicular hyperplasia. He was seropositive for antibodies to human T-lymphotropic virus type III (HTLV-III) and had serologic evidence of prior infection with cytomegalovirus, Epstein-Barr virus, and hepatitis B virus. On the other hand, he had a normal total lymphocyte count and normal T-cell subsets. Striking was the difference between the seropositivity of the high-risk donor and the seronegativity of the patient with transfusion-associated AIDS with respect to cytomegalovirus, Epstein-Barr virus, and hepatitis B virus. The demonstration of apparent transmission of HTLV-III by blood transfusion and the inability to detect evidence of infection with other viruses strongly indicate a primary etiologic role for this virus in the pathogenesis of AIDS. The high-risk blood donor continues to be an asymptomatic carrier of HTLV-III. The authors are currently comparing the HTLV-III isolates obtained from the blood donor with the HTLV-III-related RNA sequences detected in the spleen of the patient in order to determine whether molecular changes occurred after transmission of the virus that might be related to the development of AIDS.^ieng

Candida lusitaniae: a new opportunistic pathogen of the urinary tract.

A 78-year-old man with mild diabetes presented with dysuria and frequency of urination of 15 months' duration subsequent to urinary catheterization for cataract surgery. Multiple urine specimens revealed the presence of considerable quantities of yeast that were later identified as Candida lusitaniae. The patient responded well to irrigation of the bladder with amphotericin B.

[Indole alkaloids of Odyendea gabonensis]. / Alcaloïdes indoliques d'odyendea gabonensis.

From the trunk bark of Odyendea gabonensis six indole alkaloids have been isolated: Canthin-6-one (I); 5-Methoxy-canthin-6-one (II); 4,5-Dimethoxycanthin-6-one (III); 8-Hydroxy-canthin-6-one (IV); 1-Hydroxy-methyl-beta-carboline (V); and 1-Carboxamide-beta-carboline (VI). This is the first report of these products from this plant.

Brucella suis: an unusual cause of suppurative lymphadenitis in an outpatient.

A routine aerobic culture of purulent material from a draining sinus tract of a patient with chronic lymphadenitis yielded growth of a fastidious gram-negative coccobacillus later identified as Brucella suis biotype 1. The patient responded to administration of antibacterial drugs and surgical drainage.