Mystery of the memory engram: History, current knowledge, and unanswered questions

The quest to understand the memory engram has intrigued humans for centuries. Recent technological advances, including genetic labelling, imaging, optogenetic and chemogenetic techniques, have propelled the field of memory research forward. These tools have enabled researchers to create and erase memory components. While these innovative techniques have yielded invaluable insights, they often focus on specific elements of the memory trace. Genetic labelling may rely on a particular immediate early gene as a marker of activity, optogenetics may activate or inhibit one specific type of neuron, and imaging may capture activity snapshots in a given brain region at specific times. Yet, memories are multifaceted, involving diverse arrays of neuronal subpopulations, circuits, and regions that work in concert to create, store, and retrieve information. Consideration of contributions of both excitatory and inhibitory neurons, micro and macro circuits across brain regions, the dynamic nature of active ensembles, and representational drift is crucial for a comprehensive understanding of the complex nature of memory.

Comorbidity and polypharmacy impact neurobehavioral symptoms and symptom validity failure among post-9/11 veterans with mild traumatic brain injury

Objective

The study aimed to examine the association between post-concussive comorbidity burdens [post-traumatic stress disorder (PTSD), depression, and/or headache] and central nervous system (CNS) polypharmacy (five or more concurrent medications) with reported neurobehavioral symptoms and symptom validity screening among post-9/11 veterans with a history of mild traumatic brain injury (mTBI).

Setting

Administrative medical record data from the Department of Veterans Affairs (VA) were used in the study.

Participants

Post-9/11 veterans with mTBI and at least 2 years of VA care between 2001 and 2019 who had completed the comprehensive traumatic brain injury evaluation (CTBIE) were included in the study.

Design

Retrospective cross-sectional design was used in the study.

Main measures

Neurobehavioral Symptom Inventory (NSI), International Classification of Diseases, Ninth Revision, and Clinical Modification diagnosis codes were included in the study.

Results

Of the 92,495 veterans with a history of TBI, 90% had diagnoses of at least one identified comorbidity (PTSD, depression, and/or headache) and 28% had evidence of CNS polypharmacy. Neurobehavioral symptom reporting and symptom validity failure was associated with comorbidity burden and polypharmacy after adjusting for sociodemographic characteristics. Veterans with concurrent diagnoses of PTSD, depression, and headache were more than six times more likely [Adjusted odds ratio = 6.55 (99% CI: 5.41, 7.92)]. to fail the embedded symptom validity measure (Validity-10) in the NSI.

Conclusion

TBI-related multimorbidity and CNS polypharmacy had the strongest association with neurobehavioral symptom distress, even after accounting for injury and sociodemographic characteristics. Given the regular use of the NSI in clinical and research settings, these findings emphasize the need for comprehensive neuropsychological evaluation for individuals who screen positively for potential symptom overreporting, the importance of multidisciplinary rehabilitation to restore functioning following mTBI, and the conscientious utilization of symptom validity measures in research efforts.

The Military Injuries: Understanding Post-Traumatic Epilepsy Study: Understanding Relationships among Lifetime Traumatic Brain Injury History, Epilepsy, and Quality of Life

Understanding risk for epilepsy among persons who sustain a mild (mTBI) traumatic brain injury (TBI) is crucial for effective intervention and prevention. However, mTBI is frequently undocumented or poorly documented in health records. Further, health records are non-continuous, such as when persons move through health systems (e.g., from Department of Defense to Veterans Affairs [VA] or between jobs in the civilian sector), making population-based assessments of this relationship challenging. Here, we introduce the MINUTE (Military INjuries-Understanding post-Traumatic Epilepsy) study, which integrates data from the Veterans Health Administration with self-report survey data for post-9/11 veterans (n = 2603) with histories of TBI, epilepsy and controls without a history of TBI or epilepsy. This article describes the MINUTE study design, implementation, hypotheses, and initial results across four groups of interest for neurotrauma: 1) control; 2) epilepsy; 3) TBI; and 4) post-traumatic epilepsy (PTE). Using combined survey and health record data, we test hypotheses examining lifetime history of TBI and the differential impacts of TBI, epilepsy, and PTE on quality of life. The MINUTE study revealed high rates of undocumented lifetime TBIs among veterans with epilepsy who had no evidence of TBI in VA medical records. Further, worse physical functioning and health-related quality of life were found for persons with epilepsy + TBI compared to those with either epilepsy or TBI alone. This effect was not fully explained by TBI severity. These insights provide valuable opportunities to optimize the resilience, delivery of health services, and community reintegration of veterans with TBI and complex comorbidity.

Incidence and etiology of infectious diarrhea from a facility-based surveillance system in Guatemala, 2008-2012

BACKGROUND

Diarrhea is a major cause of morbidity and mortality, yet incidence and etiology data are limited. We conducted laboratory-based diarrhea surveillance in Guatemala.

METHODS

A diarrhea case was defined as ≥3 loose stools in a 24-h period in a person presenting to the surveillance facilities. Epidemiologic data and stool specimens were collected. Specimens were tested for bacterial, parasitic, and viral pathogens. Yearly incidence was adjusted for healthcare seeking behaviors determined from a household survey conducted in the surveillance catchment area.

RESULTS

From November 2008 to December 2012, the surveillance system captured 5331 diarrhea cases; among these 1381 (26%) had specimens tested for all enteric pathogens of interest. The adjusted incidence averaged 659 diarrhea cases per 10,000 persons per year, and was highest among children aged < 5 years, averaging 1584 cases per 10,000 children per year. Among 1381 (26%) specimens tested for all the pathogens of interest, 235 (17%) had a viral etiology, 275 (20%) had a bacterial, 50 (4%) had parasites, and 86 (6%) had co-infections. Among 827 (60%) specimens from children aged < 5 years, a virus was identified in 196 (23%) patients; 165 (20%) had norovirus and 99 (12%) rotavirus, including co-infections. Among 554 patients aged ≥5 years, 103 (19%) had a bacterial etiology, including diarrheagenic Escherichia coli in 94 (17%) cases, Shigella spp. in 31 (6%), Campylobacter spp. in 5 (1%), and Salmonella spp. in 4 (1%) cases. Detection of Giardia and Cryptosporidium was infrequent (73 cases; 5%).

CONCLUSIONS

There was a substantial burden of viral and bacterial diarrheal diseases in Guatemala, highlighting the importance of strengthening laboratory capacity for rapid detection and control and for evaluation of public health interventions.

Psychiatric comorbidities go unrecognized in patients with epilepsy: "You see what you know"

Patients with epilepsy (PWE) have a significantly higher prevalence of psychiatric comorbid disorders involving depression, anxiety, psychotic, and attention-deficit disorders compared with the general population or patients with other chronic medical conditions. Currently, there is no systematic approach in the evaluation and management of psychiatric comorbidities in these patients. In addition, neurologists are not trained to recognize these disorders, and consequently, they remain undertreated. Despite the high prevalence of psychiatric comorbidities in patients evaluated for epilepsy surgery, most epilepsy centers in North America do not include a psychiatric evaluation as part of the presurgical work-up. Despite the intimate relationship between psychiatric comorbidities and epilepsy, collaboration between epileptologists and psychiatrists is sparse at best and nonexistent at worse. The purpose of this paper was to highlight and try to understand the causes behind the persistent lack in communication between neurologists and psychiatrists, the gap in the training of neurologists on psychiatric aspects of neurologic disorders and vice versa and to propose new initiatives to fix the problem. This article is part of the Special Issue "Obstacles of Treatment of Psychiatric Comorbidities in Epilepsy".

Clinical Characteristics of Hospitalized Infants With Laboratory-Confirmed Pertussis in Guatemala

BACKGROUND

Pertussis is an important cause of hospitalization and death in infants too young to be vaccinated (aged <2 months). Limited data on infant pertussis have been reported from Central America. The aim of this study was to characterize acute respiratory illnesses (ARIs) attributable to Bordetella pertussis among infants enrolled in an ongoing surveillance study in Guatemala.

METHODS

As part of a population-based surveillance study in Guatemala, infants aged <2 months who presented with ARI and required hospitalization were enrolled, and nasopharyngeal and oropharyngeal swab specimens were obtained. For this study, these specimens were tested for B pertussis using real-time polymerase chain reaction (PCR).

RESULTS

Among 301 infants hospitalized with ARI, we found 11 with pertussis confirmed by PCR (pertussis-positive infants). Compared to pertussis-negative infants, pertussis-positive infants had a higher mean admission white blood cell count (20900 vs 12579 cells/μl, respectively; P = .024), absolute lymphocyte count (11517 vs 5591 cells/μl, respectively; P < .001), rate of admission to the intensive care unit (64% vs 35%, respectively; P = .054), and case fatality rate (18% vs 3%, respectively; P = .014). Ten of the 11 pertussis-positive infants had cough at presentation; the majority (80%) of them had a cough duration of <7 days, and only 1 had a cough duration of >14 days. Fever (temperature ≥ 38°C) was documented in nearly half (45%) of the pertussis-positive infants (range, 38.0-38.4°C).

CONCLUSIONS

In this study of infants <2 months of age hospitalized with ARI in Guatemala, pertussis-positive infants had a high rate of intensive care unit admission and a higher case fatality rate than pertussis-negative infants.

Rapid Active Sampling Surveys as a Tool to Evaluate Factors Associated with Acute Gastroenteritis and Norovirus Infection among Children in Rural Guatemala

We examined burden and factors associated with norovirus (NoV) acute gastroenteritis (AGE) among children in rural Guatemala. Children age 6 weeks to 17 years were enrolled into three AGE surveillance groups, using two-stage cluster sampling: a prospective participatory syndromic surveillance (PSS) cohort and two cross-sectional rapid active sampling (RAS) surveys, conducted from April 2015 to February 2016. Epidemiologic and NoV testing data were used to identify factors associated with NoV infection, AGE, and NoV+ AGE. The three cross-sectional surveys (PSS enrollment visit, RAS Survey 1, and RAS Survey 2) enrolled 1,239 children, who reported 134 (11%) AGE cases, with 20% of AGE and 11% of non-AGE samples positive for NoV. Adjusted analyses identified several modifiable factors associated with AGE and NoV infection. The cross-sectional RAS surveys were practical and cost-effective in identifying population-level risk factors for AGE and NoV, supporting their use as a tool to direct limited public health resources toward high-risk populations.

The relationship between mood disorder and insomnia depends on race in US veterans with epilepsy

PURPOSE

Few data exist on race, medical/psychiatric comorbidities, and insomnia symptoms in US veterans with epilepsy. Our aims were to examine 1) whether insomnia symptom prevalence was different between Black and White veterans and 2) whether predictors of insomnia symptoms varied by race.

METHODS

This retrospective, cross-sectional study included veterans evaluated in an epilepsy clinic over the course of 1.5years. Individuals completed standardized assessments for epilepsy and sleep complaints. Insomnia criteria were met by 1) report of difficulty with sleep initiation, maintenance, or premature awakenings accompanied by daytime impairment or 2) sedative-hypnotic use on most days of the month. Demographics, medical/psychiatric comorbidities, and medications were determined per electronic medical record review. Hierarchical multivariable logistic regression analyses were performed to determine if race, medical/mental health comorbidities, and the potential interaction of race with each comorbid condition were associated with insomnia.

RESULTS

Our sample consisted of 165 veterans (32% Black). The unadjusted prevalence of insomnia was not different between Black and White veterans (42% vs 39%, p=0.68). In adjusted analyses, the association between mood disorder and insomnia varied by race. Depressed White veterans had over 11-times higher predicted odds of insomnia (OR 11.4, p<0.001) than non-depressed White veterans, while depressed Black veterans had 4-times higher predicted odds of insomnia (OR 4.1, p=0.06) than non-depressed Black veterans. Although mood disorder diagnosis was associated with insomnia for both racial groups, White veterans had a stronger association between mood disorder diagnosis and insomnia than Black veterans.

CONCLUSIONS

The relationship between mood disorder diagnosis and insomnia was stronger for White than Black veterans with epilepsy. Future studies are needed to explore mental health symptoms and psychosocial determinants of insomnia with larger samples of minority individuals with epilepsy.

Examining Adherence Among Challenging Patients in Public and Private HIV Care in Argentina

Treatment engagement, retention and adherence to care are required for optimal HIV outcomes. Yet, patients may fall below the treatment recommendations for achieving undetectable viral load or not be retained in care. This study examined the most challenging patients in Buenos Aires, Argentina, those non-adherent to HIV care. Men (n = 61) and women (n = 59) prescribed antiretrovirals (ARVs) and non-adherent to treatment in the prior 3-6 months were enrolled and assessed regarding adherence, knowledge, motivation and attitudes regarding treatment. Private clinic patients had lower viral load and higher self-reported adherence than public clinic patients. Motivations to be adherent and positive beliefs regarding ARVs were associated with increased adherence in public clinic participants. Increased self-efficacy was associated with increased adherence among participants from both clinics. Results support patient and provider interventions that strengthen the characteristics supporting adherence, engagement and retention in public and private clinic settings.

Reversible craniocervical dystonia associated with levofloxacin

Background

Dystonia is a hyperkinetic movement disorder related to dysfunction of inhibitory basal ganglia and cortical circuits. GABA is the major inhibitory neurotransmitter in the central nervous system. Quinolones can rarely produce serious neurologic effects, which have been attributed to impaired inhibition through GABA antagonism. We report a case of reversible craniocervical dystonia associated with oral levofloxacin.

Case presentation

A 62-year-old man on hemodialysis presented with craniocervical dystonia 3 days after initiation of levofloxacin 500 mg. twice daily. Levofloxacin was discontinued. Seven days later the abnormal movements completely disappeared and did not recur in the following 3 months.

Conclusion

Levofloxacin should be considered as a rare but potentially reversible trigger of craniocervical dystonia. Older age, renal impairment and high doses of the drug might be risk factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s40734-015-0021-8) contains supplementary material, which is available to authorized users.

X-ray power and yield measurements at the refurbished Z machine

Advancements have been made in the diagnostic techniques to measure accurately the total radiated x-ray yield and power from z-pinch implosion experiments at the Z machine with high accuracy. The Z machine is capable of outputting 2 MJ and 330 TW of x-ray yield and power, and accurately measuring these quantities is imperative. We will describe work over the past several years which include the development of new diagnostics, improvements to existing diagnostics, and implementation of automated data analysis routines. A set of experiments on the Z machine were conducted in which the load and machine configuration were held constant. During this shot series, it was observed that the total z-pinch x-ray emission power determined from the two common techniques for inferring the x-ray power, a Kimfol filtered x-ray diode diagnostic and the total power and energy diagnostic, gave 449 TW and 323 TW, respectively. Our analysis shows the latter to be the more accurate interpretation. More broadly, the comparison demonstrates the necessity to consider spectral response and field of view when inferring x-ray powers from z-pinch sources.

Respiratory syncytial virus circulation in seven countries with Global Disease Detection Regional Centers

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in young children globally, with the highest burden in low- and middle-income countries where the association between RSV activity and climate remains unclear.

METHODS

Monthly laboratory-confirmed RSV cases and associations with climate data were assessed for respiratory surveillance sites in tropical and subtropical areas (Bangladesh, China, Egypt, Guatemala, Kenya, South Africa, and Thailand) during 2004-2012. Average monthly minimum and maximum temperatures, relative humidity, and precipitation were calculated using daily local weather data from the US National Climatic Data Center.

RESULTS

RSV circulated with 1-2 epidemic periods each year in site areas. RSV seasonal timing and duration were generally consistent within country from year to year. Associations between RSV and weather varied across years and geographic locations. RSV usually peaked in climates with high annual precipitation (Bangladesh, Guatemala, and Thailand) during wet months, whereas RSV peaked during cooler months in moderately hot (China) and arid (Egypt) regions. In South Africa, RSV peaked in autumn, whereas no associations with seasonal weather trends were observed in Kenya.

CONCLUSIONS

Further understanding of RSV seasonality in developing countries and various climate regions will be important to better understand the epidemiology of RSV and for timing the use of future RSV vaccines and immunoprophylaxis in low- and middle-income countries.

Nocturnal frontal lobe epilepsy presenting as excessive daytime sleepiness

Excessive daytime sleepiness (EDS) is common in the general population. Etiologies include insufficient sleep and primary sleep disorders. Due to its high prevalence, physicians often overlook EDS as a significant problem. However, EDS may also be the presenting symptom of seizures, in particular Nocturnal Frontal Lobe Epilepsy (NFLE). Due to the clinical similarity between the nocturnal behaviors of NFLE and parasomnias, and poor patient-related history, NFLE remains a challenging diagnosis. We report the case of a patient with NFLE who presented with a primary complaint of EDS, and discuss the differential diagnosis and evaluation of patients with EDS associated with nocturnal behaviors. In the context of a patient presenting with EDS and stereotyped nocturnal events, clinical suspicion should be high for NFLE.

Insomnia symptoms in South Florida military veterans with epilepsy

BACKGROUND

Despite the high prevalence of insomnia in veterans with epilepsy, it remains understudied. Our aim was to identify the associations of insomnia with epilepsy, comorbidities, and treatment-related variables in South Florida veterans.

METHODS

We performed a cross-sectional analysis of veterans attending an epilepsy clinic over 18 months. Participants completed standardized assessments of seizure and sleep. Insomnia was defined as 1) difficulty with sleep onset, maintenance, or premature awakenings with daytime consequences or 2) sedative-hypnotic use on most nights of the previous month.

RESULTS

One hundred sixty-five veterans (87% male, age 56 ± 15 years) were included: 66 reporting insomnia (40%). In logistic regression analysis, insomnia was significantly associated with post-traumatic seizure etiology, lamotrigine prescription, and mood and psychotic disorders. Female gender and levetiracetam treatment were associated with lower odds for insomnia.

CONCLUSION

Insomnia was associated with post-traumatic epilepsy, mood/psychotic comorbidities, and antiepileptic regimen. Insomnia represents an under-recognized opportunity to improve comprehensive epilepsy care.

Penetrating radiography of imploding and stagnating beryllium liners on the Z accelerator

The implosions of initially solid beryllium liners (tubes) have been imaged with penetrating radiography through to stagnation. These novel radiographic data reveal a high degree of azimuthal correlation in the evolving magneto-Rayleigh-Taylor structure at times just prior to (and during) stagnation, providing stringent constraints on the simulation tools used by the broader high energy density physics and inertial confinement fusion communities. To emphasize this point, comparisons to 2D and 3D radiation magnetohydrodynamics simulations are also presented. Both agreement and substantial disagreement have been found, depending on how the liner's initial outer surface finish was modeled. The various models tested, and the physical implications of these models are discussed. These comparisons exemplify the importance of the experimental data obtained.

Measurements of magneto-Rayleigh-Taylor instability growth during the implosion of initially solid Al tubes driven by the 20-MA, 100-ns Z facility

The first controlled experiments measuring the growth of the magneto-Rayleigh-Taylor instability in fast (∼100  ns) Z-pinch plasmas are reported. Sinusoidal perturbations on the surface of an initially solid Al tube (liner) with wavelengths of 25-400  μm were used to seed the instability. Radiographs with 15  μm resolution captured the evolution of the outer liner surface. Comparisons with numerical radiation magnetohydrodynamic simulations show remarkably good agreement down to 50  μm wavelengths.

Duration of refractory status epilepticus and outcome: loss of prognostic utility after several hours

PURPOSE

Outcome for patients with status epilepticus (SE) depends strongly on etiology. Duration of SE is also predictive, at least in the first 2 h, but beyond this it is unclear that duration of SE influences outcome significantly. We sought to determine the influence of duration of SE on outcome in patients with prolonged SE, and to compare this influence with that of other factors.

METHODS

We reviewed the clinical course and outcome of 119 patients with SE, diagnosed by both clinical manifestations and electroencephalography (EEG) evidence. Using univariate and multivariate analyses, we sought predictors of outcome (survival vs. death or vegetative state) among age, etiology (epilepsy, anoxia or severe hypoxia, or other), presence of earlier epilepsy, multiple medical problems, presentation in coma, and type of SE (focal or generalized).

RESULTS

Median duration of SE was 48 h. Survival was greater with a shorter duration, especially when <10 h (69% vs. 31% for longer duration; p < 0.05). Epilepsy as the etiology, and an earlier diagnosis of epilepsy offered a favorable prognosis (p < 0.01), but only the former on multivariate analysis. Coma and SE caused by anoxia/hypoxia were unfavorable factors. Once corrected for etiology, presentation in coma, and type of SE (focal or generalized), duration of SE did not have a significant effect on outcome. Overall mortality was high, 65%, but 10 patients survived SE lasting over 3.5 days.

CONCLUSIONS

A duration of <10 h was associated with better outcome in SE, but this was not significant once etiology, presentation in coma, and type of SE were accounted for. Etiology of SE is still the primary determinant of outcome. Unless it follows anoxia, prolonged SE should not be considered a hopeless condition.

Purification of commercial coomassie brilliant blue R-250 and characterization of the chromogenic fractions

Coomassie brilliant blue R-250 (CBB) is a popular and widely used dye for detection of proteins by gel electrophoresis. However, commercially available CBBs are complex mixtures of numerous chromogenic compounds that vary from lot to lot, thereby giving an undesirable level of variation in reproducibility, precision, and specificity in staining gels. We have developed a silica gel column chromatographic method for purification of commercial CBBs in high yield and have standardized each lot to perform equivalently in staining proteins as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and quantitative scanning densitometry. This is a major improvement in protein purity determinations by quantitative scanning densitometry. A thinlayer chromatographic method for quality control testing of the purified CBB lots was also developed. Plasma desorption mass spectrometry was used to identify components of silica gel column fractions. Scanning densitometry was the technology used to establish performance equivalency between different CBB preparations. The less polar chromogenic compounds are nonblue and/or fluorescent in color, contain mono- or unsulfonated structures, and lack significant protein binding capacity. The more polar chromogenic compounds are green and blue-green in color, contain tri- and tetrasulfonated moieties, compared to the disulfonated structure of CBB, and bind to protein at least 40 times more effectively than pure CBB. The concentrations of these highly polar chromogens differ from lot to lot and act as "inhibitors" in protein staining, thereby causing variability in protein staining.

Periodontal changes by HIV serostatus in a cohort of homosexual and bisexual men

These data represent 20 months of follow-up on 114 homo/bisexual men. Periodontal changes were analyzed in relation to HIV-1 serostatus, immune status, age and plaque. Gingival index (GI), plaque index (PI), and relative attachment levels recorded by the computerized Florida disk probe were performed every 4 months. A threshold of > or = 3.0 mm of relative attachment loss (RAL) was selected as a significant longitudinal change. RAL > or = 3 mm occurred 6.16 times (95% CI = 1.95, 19.40) more frequently among subjects with T4 counts < 200 compared to subjects with counts of 200 or more. Among older subjects (age > or = 35 years), the incidence (33%) of RAL > or = 3 mm was significantly higher (p = 0.004) in more immunosuppressed subjects (T4 < 200) compared to the incidence (5%) in less immunosuppressed subjects (T4 > or = 200); this association was not significant in younger subjects less than 35 years old (p = 0.55). In 78 subjects present at all follow-up visits, averaged GI increased and were significantly higher in the seropositive subjects compared to seronegative subjects, but, GI was not related to T4 cell counts within the seropositive group. Separate linear regression of GI by PI by HIV serostatus revealed a significantly higher slope in the seropositive group compared to the seronegative group (p = 0.04), suggesting greater sensitivity to plaque in the seropositive group.

CONCLUSION

immunosuppression, especially in combination with older age, may be a risk factor for attachment loss, and HIV seropositivity, independent of T4 cell counts, may be a risk factor for gingival inflammation.

HIV-associated oral lesions; immunologic, virologic and salivary parameters

There are numerous reports of oral lesions in HIV-infected individuals. However, few correlate the oral lesions with laboratory parameters. This study examined oral candidiasis and hairy leukoplakia, the two most common HIV-associated oral lesions, in relation to T-cell counts, p24 core antigen levels and salivary flow rates. Oral mucosal examinations, immunologic and virologic studies and stimulated whole and parotid saliva flow rates were conducted on 135 (HIV+ = 102, HIV- = 33) homosexual or bisexual men. Results indicate that, among HIV-infected subjects, the odds of having oral candidiasis is 6 times (95% CI = 0.6-56.6) greater for subjects with T4 counts between 200-399 per mm3, and 23 times (95% CI = 2.8-193.0) greater for subjects with T4 counts less than 200/mm3 compared to subjects with T4 counts of 400/mm3 or greater. Subjects had an equal likelihood of having hairy leukoplakia at different levels of immunocompetence. The prevalence of oral candidiasis and hairy leukoplakia was higher among subjects with infectious virus in their serum, but was only statistically significant for hairy leukoplakia (p = 0.01).

Recovery of infectious HIV-1 from whole saliva

Whole saliva and serum samples were collected from 75 HIV-infected homosexual or bisexual men. Thirty-eight percent of cultured sera were positive for cell-free, infectious virus while only 1 percent of the 218 cultured whole salivas contained cell-free, infectious virus. These data support previous studies suggesting unlikely potential transmissibility of HIV infection by saliva.

Differential migration of lymphoblasts and small lymphocytes induced by mitogens in culture: characteristics of lymphoid cells

Lymphoid cells from peripheral lymph nodes, spleen, and gut-associated lymphoid tissues (mesenteric lymph nodes and Peyer's patches) of the mouse were stimulated by concanavalin A and bacterial lipopolysaccharide in culture: their migration in the mouse was studied. Lymphoblasts and small-medium lymphocytes from the cultures, irrespective of their tissue origins, showed a differential migration when they were passively transferred into syngeneic, immunoglobulin-allotype congeneic or allogeneic recipients. Large lymphoblasts, at late S and G2 + M phases and without MEL-14 reactive determinants, migrated preferentially to the gut. In contrast, small and medium lymphocytes, at Go/Gl and early S phases and with MEL-14 reaction determinants, migrated preferentially to the spleen and liver. The differential migration was shown to be an inherent characteristic of the cultured lymphoid cells. These results suggest that selective migration and lodging of lymphoid cells in the body may be determined by the phases of cell cycle and stages of differentiation.

On the isolation of 2-hydroxydocosanoic and 2-hydroxytricosanoic acids from the marine sponge Amphimedon compressa

The first alpha-hydroxy fatty acids from a marine sponge, namely 2-hydroxydocosanoic and 2-hydroxytricosanoic, were identified in the Caribbean sponge Amphimedon compressa. These acids were found to occur in phosphatidylethanolamine and phosphatidylserine and constituted 52% of the total fatty acid mixture of this sponge. The long chain fatty acids 5,9,23-nonacosatrienoic (29:3) and 5,9,23-tricontatrienoic (30:3), as well as a new tetratricontatetraenoic (34:4) acid, were also found in A. compressa.