First-trimester cavum veli interpositi: prevalence and natural history

OBJECTIVE

To confirm the identity and assess the prevalence and evolution of the fluid-filled interhemispheric midline structure, thought to be the cavum veli interpositi (CVI), in fetuses at 11-14 weeks' gestation.

METHODS

This was a retrospective study of first-trimester ultrasound scans performed at a single center over 3 months. Inclusion criteria were singleton pregnancies at 11-14 weeks' gestation with known neonatal outcome. Five experts reviewed the images. Mixed-effects logistic regression and generalized estimating equations (GEE) were conducted to analyze the associations between the presence of the structure and variables including ultrasound approach (transabdominal vs transvaginal), maternal body mass index (BMI), gestational age, fetal crown-rump length (CRL) and biparietal diameter (BPD). Second-trimester ultrasound scans of the fetal central nervous system at 18-24 weeks' gestation were evaluated for the persistence of the CVI in fetuses in which the structure was observed in the first trimester.

RESULTS

Of the 223 cases reviewed, 104 were included, among which the CVI was observed in 25 (24%) cases. There was no statistically significant difference in CVI visualization between transabdominal and transvaginal ultrasound examinations. GEE showed significant associations between the presence of the fetal structure and CRL (odds ratio (OR) per 10-unit increase, 1.32; P < 0.0001) and BPD (OR per 10-unit increase, 1.88; P = 0.0011). Maternal BMI and gestational age showed no significant effect on the presence of the CVI. At second-trimester follow-up of the 25 fetuses in which the CVI was observed initially, 44% still showed a CVI, 32% exhibited a cavum vergae, 4% had both structures and 20% had neither.

CONCLUSIONS

Based on its anatomical location and, in some fetuses, its visualization as a distinct entity from the third ventricle, the identity of the interhemispheric midline structure in the suprathalamic region of the fetal brain between 11-14 weeks' gestation was confirmed as the CVI. The CVI and/or cavum vergae persisted into the second trimester in 80% of fetuses identified initially as having a CVI. Its presence is not linked to pathology, offering reassurance to practitioners and parents. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

The impact of baseline transmitral diastolic mean gradient on left atrial pressure reduction in patients undergoing transcatheter mitral valve edge-to-edge repair

BACKGROUND

Elevated transmitral gradient post transcatheter mitral valve edge-to-edge repair (TEER) has been associated with worse outcomes. Whether an elevated baseline transmitral diastolic mean gradient (MG) ≥5 mmHg is associated with hemodynamic outcomes after TEER is unknown.

METHODS

A total of 164 consecutive patients undergoing TEER at Mayo Clinic between June 2014 and May 2018 were analyzed in this retrospective study. Baseline demographics, as well as clinical, echocardiographic, and procedural data were obtained. Data on direct left atrial pressure (LAP) before and after TEER were recorded. Logistic regression models were constructed to evaluate the association between preprocedure transmitral diastolic mean gradient (pre-MG) and (1) improvement in LAP following TEER, (2) postprocedure transmitral diastolic mean gradient (post-MG). A decrease in LAP post TEER was considered an improvement in hemodynamic response. Pre-MG was categorized as: ≥5 and <5 mmHg.

RESULTS

Median age of the cohort was 81.5 years (Q1: 76.3, Q3: 87) and 34% were female. At baseline, median transmitral diastolic MG was 4 mmHg (Q1: 3, Q3: 5) and median LAP was 19 mmHg (Q1:16, Q3: 23.5). In a multivariable model, adjusted for age and sex, patients with pre-MG ≥ 5 mmHg were less likely to see an improvement in LAP post TEER (adjusted odds ratio [aOR]: 0.22, 95% confidence interval [CI]: 0.09, 0.55; p = 0.001) and more likely to have elevated post-MG (aOR; 7.08, 95% CI: 2.93, 17.13; p < 0.001).

CONCLUSION

Higher pre-MG (≥5 mmHg) was associated with a lower reduction in LAP and higher residual transmitral gradient following TEER suggesting other potential contributors to increased LAP besides mitral regurgitation as a cause of elevated baseline MG.

Quantitative systems pharmacology modeling sheds light into the dose response relationship of a trispecific T cell engager in multiple myeloma

In relapsed and refractory multiple myeloma (RRMM), there are few treatment options once patients progress from the established standard of care. Several bispecific T-cell engagers (TCE) are in clinical development for multiple myeloma (MM), designed to promote T-cell activation and tumor killing by binding a T-cell receptor and a myeloma target. In this study we employ both computational and experimental tools to investigate how a novel trispecific TCE improves activation, proliferation, and cytolytic activity of T-cells against MM cells. In addition to binding CD3 on T-cells and CD38 on tumor cells, the trispecific binds CD28, which serves as both co-stimulation for T-cell activation and an additional tumor target. We have established a robust rule-based quantitative systems pharmacology (QSP) model trained against T-cell activation, cytotoxicity, and cytokine data, and used it to gain insight into the complex dose response of this drug. We predict that CD3-CD28-CD38 killing capacity increases rapidly in low dose levels, and with higher doses, killing plateaus rather than following the bell-shaped curve typical of bispecific TCEs. We further predict that dose–response curves are driven by the ability of tumor cells to form synapses with activated T-cells. When competition between cells limits tumor engagement with active T-cells, response to therapy may be diminished. We finally suggest a metric related to drug efficacy in our analysis—“effective” receptor occupancy, or the proportion of receptors engaged in synapses. Overall, this study predicts that the CD28 arm on the trispecific antibody improves efficacy, and identifies metrics to inform potency of novel TCEs.

Outcomes of Radial Versus Femoral Access in Patients With Severe Aortic Stenosis Undergoing Percutaneous Coronary Intervention Prior to Transcatheter Aortic Valve Replacement

BACKGROUND

The safety and feasibility of radial access in patients undergoing percutaneous coronary intervention (PCI) prior to transcatheter aortic valve replacement (TAVR) has not been studied.

METHODS

This study included consecutive patients who underwent PCI within 30 days before TAVR at Mayo Clinic. Vascular access was left to the discretion of the operator. Baseline demographics, procedural data, PCI outcomes, and subsequent transfemoral TAVR outcomes were extracted from patient charts.

RESULTS

A total of 331 patients were included in this study, with 107 patients undergoing PCI via radial access (rPCI), and 224 via femoral access (fPCI). Mean age was 80.6 years and 35.6% were females (35.5% rPCI vs 35.3% fPCI). More patients in the fPCI group had previous coronary artery bypass graft surgery (13.1% rPCI vs 34.4% fPCI; P<.001). Fluoroscopy time (13.36 minutes vs 18.86 minutes; P<.001) and contrast use (115 mL vs 140 mL; P<.01) were lower in the rPCI group than in the fPCI group. Crossover rate from radial to femoral was 6.5%. There were more access-site hematomas in the fPCI group (2.8% rPCI vs 14.3% fPCI; P<.001), with no statistically significant rate of other access-related complications. There was no difference in stroke, myocardial infarction, cardiac arrest, or unplanned surgery. There was no difference in bleeding or stroke between both groups during subsequent transfemoral TAVR.

CONCLUSION

Radial access for pre-TAVR PCI is feasible and safe and is associated with a lower rate of access-site hematoma. This study supports the increased use of transradial access for pre-TAVR PCI.

30-day patient reported outcomes can be predicted by change in left atrial pressure and not change in transmitral gradient following MitraClip

BACKGROUND

Change in left atrial pressure (LAP) has been shown to be associated with symptom improvement post-MitraClip; however, the association between acute procedural changes in transmitral diastolic mean gradient (MG) compared to LAP and symptom improvement is not well established.

METHODS

164 consecutive patients undergoing MitraClip at Mayo Clinic between June 2014 and May 2018 were included. Preclip and postclip MG and LAP were recorded. Baseline demographics, clinical, and echocardiographic outcomes, including 30-day New York Heart Association (NYHA) functional status were obtained from patient charts.

RESULTS

Median age was 81.5 years (IQR: 76.3, 87), 34% were female and 94.5% had NYHA class III and IV functional status at baseline. At baseline, median MG was 4 mmHg (IQR: 3, 5) and LAP was 19 mmHg (IQR: 16, 23.5). Following MitraClip deployment, the median MG was 4 mmHg (IQR: 3, 6) and the median LAP was 17 mmHg (IQR: 14, 21), 69.5% of patients had less than moderate MR. There was no statistically significant association between change in MG and NYHA functional class at 30 days (OR = 0.95, 95% CI: 0.76-1.20). However, a reduction in LAP following MitraClip deployment was significantly associated with improvement in NYHA functional status at 30 days following adjustments for age and sex (aOR 3.36, 95% CI: 1.34-8.65). There was no significant correlation between change in mean LAP and change in MG (p = .98).

CONCLUSION

Unlike change in left atrial pressure, change in MG post-MitraClip was not associated with patient reported outcomes at 30 days and did not correlate with change in left atrial pressure. Long-term follow up is needed to evaluate the impact of LA pressure on symptoms.

Changing the Culture: Improving Helmet Utilization to Prevent Traumatic Brain Injury

BACKGROUND

Several groups have instituted helmet initiatives with varying success across the world. Helmet use has been well documented to prevent traumatic brain injury. Despite the known benefits, many people, including university students, refuse to utilize helmets when riding bikes, mopeds, or motorcycles. We recognized a need within our community regarding the lack of helmet use at University of Florida and developed a program to institute change.

METHODOLOGY

We identified community champions and hosted weekly round table discussion initiatives. Through these round table discussions we identified events already going on within the community and developed new opportunities to promote helmet use. We had stories from survivors and parents, utilized school administration support, and partnered with local bike shops.

RESULTS

The pilot initiative was successful in increasing awareness across the city and got stakeholders excited in the process. It also spearheaded more data driven initiatives that will look at reduction of traumatic brain injuries in the clinical setting.

CONCLUSION

This project highlights the University of Florida Helmet Initiative that has already generated renewed interest in safety and traumatic brain injury prevention. The school of nursing has implemented safety protocols and further support is being garnered by the administration across campus. Most importantly we have identified community champions that will carry the work forward.

Identifying and Overcoming Roadblocks that Limit the Translation of Research Findings to the Achievement of Health Equity

Almost two decades ago, the Institute of Medicine's Clinical Research Roundtable commented on the major challenges of moving health related basic science discovery to the clinical setting. The roadblocks identified included challenges in evaluating a discovery's application to human disease, and, if justified, getting that application out to the general population. The obstacles to achieving this translation of discovery to improvements in human health remain today and are most evident in populations at highest risk for inequitably poor health. We address four potential roadblocks which, if solved, will have a great impact on achieving health equity. They are expanding the definition of basic discovery to include all facets of health disparities science, understanding the daily factors that affect a community's well-being, including diverse populations in clinical trials, and training the right scientists to perform the community-engaged research required to move discovery to application in the community.

Thyrotoxic Valvulopathy: Case Report and Review of the Literature

We report a 42-year-old female who was admitted for abdominal pain, and also endorsed dyspnea, fatigue and chronic palpitations. Past medical history included asthma, patent ductus arteriosus repaired in childhood and ill-defined thyroid disease. Physical examination revealed blood pressure of 136/88 mm Hg and heart rate of 149 beats per minute. Cardiovascular exam revealed an irregularly irregular rhythm, and pulmonary exam revealed mild expiratory wheezing. Abdomen was tender. Electrocardiogram revealed atrial fibrillation with rapid ventricular response which responded to intravenous diltiazem. Labs revealed TSH of < 0.1 mU/L and free T4 of 2.82 ng/dL, a positive TSH-receptor and thyroid peroxidase antibodies suggesting Grave’s thyrotoxicosis. A transthoracic echocardiogram reported an ejection fraction of 55-60%, with mild to moderate mitral regurgitation (MR) and moderate to severe tricuspid regurgitation (TR) and dilated right heart chambers. Pulmonary artery systolic pressure was 52 mm Hg. Transesophageal echocardiogram revealed a myxomatous tricuspid valve with thickening and malcoaptation of the leaflets and moderate to severe TR, mild to moderate MR with mild thickening of the mitral valve leaflets. Abdominal ultrasound revealed wall thickening of the gall bladder concerning for acute cholecystitis. She underwent laparoscopic cholecystectomy and was discharged in stable condition on methimazole for her thyroid disease, and on oral diltiazem for rate control and anticoagulation for atrial fibrillation. Follow-up visit with her cardiologist few months later documented absence of cardiac symptoms, and no murmurs were reported on physical examination. This case underscores the importance of maintaining a high index of suspicion for hyperthyroidism when faced with significant newly diagnosed pulmonary hypertension and TR, as treatment of the thyroid abnormalities can reverse these cardiac findings.

Anastrozole and goserelin combination as first treatment for premenopausal receptor positive advanced or metastatic breast cancer: A phase II trial

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Background: Aromatase inhibitors (AIs) have shown high activity in postmenopausal women. However, as AIs do not suppress ovarian oestrogen synthesis, they are not effective in premenopausal women. The aim of this trial was to assess the efficacy of the combination of anastrozole and goserelin (LHRH agonist) in premenopausal women with advanced or metastatic hormonal receptor positive breast cancer. Methods: Premenopausal women with advanced estrogen receptor (ER) and/or progesterone receptor (PR) positive breast cancer were enrolled in this open, multicentre, non-comparative phase II trial and received anastrozole 1mg/day p.o. and gosereline 3.6 mg subcutaneously monthly until progression. The primary endpoint was objective response rate (ORR) assessed according to RECIST criteria. Results: Thirty-three patients (33), with a mean age of 44 (+ 5.9) years, PS 0–2, were enrolled from December 2001 to May 2005. All patients were ER positive and 75.8% PR positive and 6 patients (18.2%) received adjuvant treatment with anti estrogens. There were 4 (12.1%) complete responses (CR), 14 (42.4%) partial responses (PR), and 11 (33.3%) stable diseases (SD), giving an ORR of 54.6% (IC 95% [36.4; 71.9]). Twenty-one (63.6%) patients showed a clinical benefit (CR+PR+SD≥24 weeks) for a median duration of 13.7 (IC 95% [8.74; 22.97]) months. Median time to progression was 13 (6;33) months. The most commun AEs were hot flush in 29 (87.9%), arthralgia in 13 (39.4%) and nausea in 12 (36.4%) patients. Conclusions: The combination of anastrozole and gosereline is well tolerated and appears to be an effective treatment of premenopausal women with advanced breast cancer in this exploratory phase II trial.

No significant financial relationships to disclose.

Antinociceptive and anti-inflammatory effects of the ethyl acetate stem bark extract of Bridelia scleroneura (Euphorbiaceae)

Bridelia scleroneura is a member of the Euphorbiaceae family. In folk medicine in Cameroon, the stem bark of this plant is used for relieving abdominal pain, contortion, arthritis and inflammation. In this study, the antinociceptive and anti-inflammatory activities of the ethyl acetate stem bark extract have been evaluated. The putative analgesic effect of the plant extract was examined in abdominal constriction, hot plate, formalin and on pain using tail immersion mouse models and in carrageenan-induced paw edema in rats. The extract (150-600 mg/kg) exhibited a dose-dependent analgesic effect (46.27-78.97%) in acetic acid-induced abdominal constriction in mice. B. scleroneura extract increased the pain latency of nociceptive response to thermal stimuli at the higher dose of 600 mg/kg. B. scleroneuna induced significant dose-dependent reduction of the nociception in both early and late phases of the formalin test. The extract at the dose of 300 mg/kg, increased significantly, by 63.70% and 52.01% the tail-immersion latency time, 1 and 2 h post-dosing. In the carrageenan test, B. scleroneura (150-600 mg/kg, p.o) had dose-dependent and significant effects at different time intervals. This behaviour was similar to indometacin (10 mg/kg) used as a standard drug. These results show that the ethyl acetate stem bark extract of B. scleroneura possesses peripheral and central analgesic properties as well as anti-inflammatory activity against acute inflammation processes, in support of the folk medicinal use of the plant.

Patient reperfusion preferences in acute myocardial infarction: mortality versus stroke, benefits versus costs, high technology versus drugs

BACKGROUND

Reperfusion therapy, thrombolysis and primary percutaneous coronary intervention (PCI) decrease mortality in ST elevation acute myocardial infarction. Tissue plasminogen activator (tPA) reduces the risk of death but at an increased risk of stroke and cost compared with streptokinase (SK). PCI reduces the risk of death and stroke compared with tPA, but at increased costs. The authors explored patient preferences for the various reperfusion strategies.

PATIENTS AND METHODS

Among patients hospitalized with an acute coronary syndrome, preferences for tPA or SK were determined using a questionnaire based on Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-1) trial data including risk of death, stroke and the combination of the two. The impact of cost was assessed under the assumption of government or patient payment. Overall, the societal preference was solicited based on all the data. A similar survey was conducted comparing primary PCI with tPA using outcome data from a Cochrane review.

RESULTS

When viewed in the context of net clinical benefit (NCB), 66.7% of patients chose tPA over SK. The preference for tPA diminished under the scenario of patient payment compared with government payment. However, as a societal strategy, the preference for tPA was 40.5% (P<0.001 versus NCB). Preference for primary PCI over tPA was strong whether based on risk of death (78.5%), stroke (88.1%) or NCB (95.4%). Cost considerations resulted in a slight fall in PCI preference (87.7%). As an overall societal strategy, 81.0% chose primary PCI over tPA (P=0.016 versus NCB). The preference for PCI was twice that for the most effective, but perhaps riskier, thrombolytic agent (tPA) (P<0.0001).

CONCLUSIONS

Preference for the potentially inferior thrombolytic agent appears to depend on the lesser risk of stroke and the lower cost. Primary PCI was preferred by patients likely due to the lower risk of death and stroke, despite the increased cost. The preferences appeared to be influenced by societal costs. In addition, the allure and heightened expectations of high technology may play a role.

Mobilization of the cell adhesion glycoprotein F3/contactin to axonal surfaces is activity dependent

F3/contactin is a cell adhesion/recognition molecule of the immunoglobulin superfamily implicated in axonal growth. We examined its subcellular distribution and mobilization to the cell surface in oxytocin- (OT-) secreting neurons, which express it throughout life and the axons of which undergo activity-dependent remodelling. This was performed in hypothalamic organotypic slice cultures containing OT neurons with properties of adult neurosecretory cells. Immunocytochemistry and immunoblot analysis confirmed that OT neurons express high levels of F3/contactin in vitro. Light and confocal microscopy of cultures that underwent double immunofluorescence after fixation showed F3/contactin immunoreactivity throughout the cytoplasm of OT somata, dendrites and axons, and also in non-OT axons and in putative synaptic boutons which contacted OT neurons. By contrast, after treatment of live cultures with anti-F3/contactin antibodies followed by double immunofluorescence for the glycoprotein and OT, F3/contactin immunoreactivity was visible only on the surface of axons, whether or not OT-immunoreactivity was present. Because of its glycosylphosphatidyl-inositol (GPI) linkage, F3/contactin can occur in a membrane-bound or soluble form. As seen from immunocytochemistry of live cells and immunoblot analysis, treatment of cultures with a GPI-specific phospholipase C (GPI-PLC) resulted in loss of F3/contactin immunoreactivity from all cell surfaces. F3/contactin immunoreactivity reappeared on axonal surfaces within 5 h after enzyme washout. Such re-expression was accelerated by neuronal activity facilitation (by K+ depolarization or gamma-aminobutyric acid (GABA)-A receptor blockade with bicuculline) and inhibited by neuronal activity repression [by blockade of Ca2+ channels with Mn2+, Na+ channels with tetrodotoxin (TTX) or excitatory inputs with glutamate antagonists]. Our observations establish therefore that F3/contactin surface expression in hypothalamic neurons is polarized to the axons where it occurs mainly in a GPI-linked form. We also provide direct evidence that externalization of F3/contactin depends on Ca2+ entry and neuronal electrical activity. Taken together with our earlier finding that the glycoprotein is localized in neurosecretory granules, we demonstrate that F3/contactin is mobilized to the axonal surface via the activity-dependent regulated pathway, thus arriving at the correct place and time to intervene in activity-dependent remodelling of axons.

Inhibition of intra-abdominal adhesions: a comparison of hemaseel APR and cryoprecipitate fibrin glue

Our previous studies demonstrated fibrin glue (FG) prepared from cryoprecipitate (cryo) inhibits intra-abdominal adhesions in rats. A new FG, Hemaseel APR, is Food and Drug Administration (FDA) approved for hemostasis during cardiac surgery and splenic trauma. This study was undertaken to determine if Hemaseel FG prevents intra-abdominal adhesions, and to compare it to cryo FG. Forty-five rats underwent laparotomy. Bilateral peritoneal-muscular defects were created. Polypropylene mesh was sewn into each defect with a running silk suture. The bowel was abraded with gauze. The rats were then randomized to mesh covered with Hemaseel FG, cryo FG, or control. On postoperative day 7, the severity of adhesions were graded by percentage of mesh covered by adhesion (0-100%) and degree of adhesion (0-3). The mean percentage of mesh covered by adhesion was 9% for Hemaseel FG, 43% for cryo FG (p = .005), and 65% for the controls (p < .0001). The mean density adhesion score was 0.5 for Hemaseel FG, 1.2 for cryo FG (p = .04), and 2.1 for the controls (p < .0001). In the Hemaseel FG group, 77% of patches had no adhesions, compared with 37% in the cryo FG group (p = .004) and 13% in the controls (p < .0001). Thus, Hemaseel FG significantly decreases intra-abdominal adhesions, and is more effective than cryo FG.

The polysialylated neural cell adhesion molecule reaches cell surfaces of hypothalamic neurons and astrocytes via the constitutive pathway

Understanding how neurons and glia sort and deliver cell adhesion molecules to their cell surface should provide important clues as to how such molecules participate in dynamic neuronal functions in the developing and adult brain. The present study examines translocation of polysialylated neural cell adhesion molecule (PSA-NCAM), a negative regulator of cell adhesion, in cells of the rat hypothalamo-neurohypophysial system in which it is expressed throughout life and which undergo morphological remodelling in response to stimulation. PSA-NCAM expression in this system does not vary markedly in relation to different conditions of regulated neurosecretion, suggesting that the glycoprotein reaches cell surfaces via the constitutive pathway. To study this more directly, we here used immunofluorescence for PSA on NCAM in live, unpermeabilized cells to monitor PSA-NCAM surface expression in organotypic slice cultures from postnatal rat hypothalami. Subsequent immunolabelling for oxytocin confirmed that the cultures included magnocellular oxytocinergic neurons displaying many properties of adult neurosecretory neurons in situ. In the cultures, immunoreaction for PSA-NCAM was visible on the surface of oxytocinergic and non-oxytocinergic axons. This reaction disappeared after exposure of the cultures to endoneuraminidase, an enzyme which specifically cleaves alpha-2-8-linked PSA from NCAM. PSA-NCAM reappeared on axonal surfaces 4h after enzyme washout. Such reexpression was visibly not affected by neuronal activity inhibition (blockade of Ca(2+) channels with Mn(2+), of Na(+) channels with tetrodotoxin, or of glutamate receptors with 6-cyano-7-nitroquinoxaline-2,3-dione or D-2-amino-5-phosphonopentanoic acid) or facilitation (K(+) depolarization or GABA-A receptor blockade with bicuculline). In contrast, PSA-NCAM surface translocation was inhibited reversibly by cooling the cultures at 20 degrees C, a procedure which blocks constitutive secretion and which resulted in accumulation of PSA-NCAM in the cytoplasm of oxytocinergic and non-oxytocinergic neurons. This treatment also revealed PSA-NCAM in the cytoplasm of underlying astrocytes. Our observations provide direct evidence that PSA-NCAM reaches the cell surface of hypothalamic neurons and astrocytes via the constitutive pathway, independently of Ca(2+) entry and enhanced neuronal activity. Thus, PSA-NCAM in the hypothalamo-neurohypophysial system would be continuously available to permit its cells to undergo remodelling whenever the proper stimulus intervenes.

Cell-specific localization of monocarboxylate transporters, MCT1 and MCT2, in the adult mouse brain revealed by double immunohistochemical labeling and confocal microscopy

Recent evidence suggests that lactate could be a preferential energy substrate transferred from astrocytes to neurons. This would imply the presence of specific transporters for lactate on both cell types. We have investigated the immunohistochemical localization of two monocarboxylate transporters, MCT1 and MCT2, in the adult mouse brain. Using specific antibodies raised against MCT1 and MCT2, we found strong immunoreactivity for each transporter in glia limitans, ependymocytes and several microvessel-like elements. In addition, small processes distributed throughout the cerebral parenchyma were immunolabeled for monocarboxylate transporters. Double immunofluorescent labeling and confocal microscopy examination of these small processes revealed no co-localization between glial fibrillary acidic protein and monocarboxylate transporters, although many glial fibrillary acidic protein-positive processes were often in close apposition to elements labeled for monocarboxylate transporters. In contrast, several elements expressing the S100beta protein, another astrocytic marker found to be located in distinct parts of the same cell when compared with glial fibrillary acidic protein, were also strongly immunoreactive for MCT1, suggesting expression of this transporter by astrocytes. In contrast, MCT2 was expressed in a small subset of microtubule-associated protein-2-positive elements, indicating a neuronal localization. In conclusion, these observations are consistent with the possibility that lactate, produced and released by astrocytes (via MCT1), could be taken up (via MCT2) and used by neurons as an energy substrate.

Differential expression of two adhesion molecules of the immunoglobulin superfamily, F3 and polysialylated NCAM, in hypothalamic magnocellular neurones capable of plasticity

The adult hypothalamo-neurohypophysial system undergoes activity-dependent, reversible morphological changes which result in reduced astrocytic coverage of its neurones and an increase in their synaptic contacts. Our recent observations show that neurones and glia of the hypothalamo-neurohypophysial system continue to express 'embryonic' molecular features which may underlie their capacity to undergo such plasticity. These include expression of cell surface molecules like the glycosyl phosphatidyl inositol (GPI)-linked glycoprotein F3, which intervenes in axonal outgrowth, and the polysialylated isoform of the neural cell adhesion molecule (PSA-NCAM), which reduces cell adhesion and promotes dynamic cell interactions. F3 is colocalised with vasopressin and oxytocin hormones in neurosecretory granules and follows an activity-dependent, regulated pathway for surface expression on neurohypophysial axons. In contrast, PSA-NCAM appears to follow a constitutive pathway, independent of the activity of the hypothalamo-neurohypophysial system, for expression on axonal and glial surfaces, in the hypothalamic magnocellular nuclei and in the neurohypophysis. The role of F3 remains to be determined but in view of its presumptive functions during development, we propose that it promotes remodelling of neurosecretory terminals. On the other hand, we provide direct evidence that surface expression of PSA on NCAM is essential to morphological plasticity since its specific enzymatic degradation in vivo inhibited the neuronal-glial and synaptic changes normally induced by stimulation of secretion from the hypothalamo-neurohypophysial system.

Regulated expression of the cell adhesion glycoprotein F3 in adult hypothalamic magnocellular neurons

F3, a glycoprotein of the immunoglobulin superfamily implicated in axonal growth, occurs in oxytocin (OT)-secreting and vasopressin (AVP)-secreting neurons of the adult hypothalamo-neurohypophysial system (HNS) whose axons undergo morphological changes in response to stimulation. Immunocytochemistry and immunoblot analysis showed that during basal conditions of HNS secretion, there are higher levels of this glycosylphosphatidyl inositol-anchored protein in the neurohypophysis, where their axons terminate, than in the hypothalamic nuclei containing their somata. Physiological stimulation (lactation, osmotic challenge) reversed this pattern and resulted in upregulation of F3 expression, paralleling that of OT and AVP under these conditions. In situ hybridization revealed that F3 expression in the hypothalamus is restricted to its magnocellular neurons and demonstrated a more than threefold increase in F3 mRNA levels in response to stimulation. Confocal and electron microscopy localized F3 in secretory granules in all neuronal compartments, a localization confirmed by detection of F3 immunoreactivity in granule-enriched fractions obtained by sucrose density gradient fractionation of rat neurohypophyses. F3 was not visible on any cell surface in the magnocellular nuclei. In contrast, in the neurohypophysis, it was present not only in secretory granules but also on the surface of axon terminals and glia and in extracellular spaces. Taken together, our observations reveal that the cell adhesion glycoprotein F3 is colocalized with neurohypophysial peptides in secretory granules. It follows, therefore, the regulated pathway of secretion in HNS neurons to be released by exocytosis at their axon terminals in the neurohypophysis, where it may intervene in activity-dependent structural axonal plasticity.

Factors governing activity-dependent structural plasticity of the hypothalamoneurohypophysial system

1. The adult hypothalamoneurohypophysial system (HNS) undergoes reversible morphological changes in response to physiological stimulation. 2. In the hypothalamus, stimulation of neurohormone secretion results in reduced astrocytic coverage of oxytocinergic somata and dendrites so that their surfaces become directly juxtaposed. Concurrently, there is a significant increase in the number of GABAergic, glutamatergic. and noradrenergic synapses impinging on the neurons. 3. In the neurohypophysis, stimulation induces retraction of pituicyte processes from the perivascular area and enlargement and multiplication of neurosecretory terminals. 4. These neuronal-glial and synaptic changes are reversible with cessation of stimulation, thus rendering the HNS an excellent model to study physiologically linked structural neuronal plasticity in the adult CNS. 5. We still do not know the cellular mechanisms and factors underlying such plasticity. Recent studies indicate, however, that the adult HNS expresses molecular characteristics normally associated with histogenesis and/or tissue reorganization in developing or regenerating neural systems. They include expression of cell adhesion molecules such as the highly sialylated isoform of the neural cell adhesion molecule, PSA-NCAM, and the glycoproteins, F3 and tenascin-C. 6. The expression of PSA-NCAM and tenascin-C does not show striking differences in terms of age, sex or physiological condition but that of F3 varies considerably with neurohypophysial stimulation. 7. We postulate that such molecular features allow magnocellular neurons and their glia to undergo neuronal-glial and synaptic plasticity throughout life, provided the proper stimulus intervenes. 8. Thus, in the hypothalamic nuclei, centrally released oxytocin acting in synergy with steroids can induce such plasticity, while adrenaline, acting through beta-adrenergic mechanisms, does so in the neurohypophysis.

Expression of high levels of the extracellular matrix glycoprotein, tenascin-C, in the normal adult hypothalamoneurohypophysial system

Glia and neurons of the hypothalamoneurohypophysial system (HNS) undergo reversible morphological changes, which are concomitant with the remodelling of afferents onto the neurons, under different conditions of neurohormone secretion. Here, we show that the adult rat HNS contains high levels of tenascin-C (TN-C), which is an extracellular matrix glycoprotein whose expression is usually associated with neuronal-glial interactions in the developing and lesioned central nervous system (CNS). By using light and electron microscopic immunocytochemical procedures, we visualized TN-C immunoreactivity in the hypothalamic supraoptic (SON) and paraventricular nuclei, where somata of the neurons are localized; in the median eminence, where their axons transit; and in the neurohypophysis, where they terminate. Hypothalamic areas adjacent to the magnocellular nuclei were devoid of immunoreactivity. Electron microscopy of the neurohypophysis showed immunolabelling of perivascular spaces, glial (pituicyte) and axonal surfaces, a type of labelling that also characterized the median eminence. In the hypothalamic nuclei, there was labelling of extracellular spaces and astrocytic surfaces. In normal animals, we detected no cytoplasmic reaction in glia somata, neurons, or endothelial cells. However, in animals treated with the intracellular transport blocker colchicine, there was intracytoplasmic labelling of all HNS glial cells, indicating a glial source for TN-C. Immunoblot analysis revealed TN-C isoforms of apparent high molecular weight (225, 240, and 260 kD) in the SON and median eminence, whereas lower MW forms (190/200 kD) predominated in the neurohypophysis. By using immunocytochemistry and immunoblot analysis, we found no visible differences in TN-C expression in relation to age, sex, or differing neurohypophysial secretion, which suggests that the expression of TN-C is a permanent feature of the HNS.

Environmental health in minority and other underserved populations: Benign methods for identifying lead hazards at day care centres of New Orleans

This study tests the hypothesis that exterior sources of lead dust are more important than interior sources in the route of exposure of children. Benign field methods were used to distinguish between potential and actual lead exposure problems. Utilising hand wipe and surface wipe techniques, hand and environmental samples were obtained from selected day care centres at different locations within New Orleans. Previous research has shown that soil lead is determined by location within the city. Private and public day care centres were selected from inner and outer city areas to estimate the extent of hand lead exposure. To measure and identify the extent of environmental lead exposure, hand wipes were taken before and after playing outdoors. Results of preliminary findings show that outdoor lead dust is a more potent contaminant of hands than indoor lead dust. An association was found between the amount of lead on children's hands after playing outdoors and the lead content in the exterior dust and soil. Although two girls out of forty children had exceptionally high hand lead quantities after playing outdoors, in general, boys have higher hand lead levels than girls. The private inner-city day care centre had a severe contamination problem in its outdoor play area. By contrast, the outdoor play area of the public inner city day care centre is of such a high quality that the quantity of lead dust is independent of location in the city.

Expression of a glycosyl phosphatidylinositol-anchored adhesion molecule, the glycoprotein F3, in the adult rat hypothalamo-neurohypophysial system

The F3 cell surface glycoprotein consists of six immunoglobulin-like domains, four fibronectin type III repeats and a glycosylphosphatidylinositol anchor and is found in membrane-bound and soluble form. Until now, it has been localized mainly on axons of subsets of developing and postnatal neurons and has been implicated in axonal growth and synaptogenesis. We here examined its expression in the adult rat hypothalamo-neurohypophysial system composed of magnocellular neurons whose axons can undergo remodelling in adulthood in response to lesion or physiological stimulation. Immunoblot analyses demonstrated high levels of F3 immunoreactivity in the hypothalamic nuclei containing the somata of the neurons, in the median eminence, through which pass their axons and in the neurohypophysis, where they terminate. The amount of F3 detected in the latter was 2-fold that in the hypothalamus. In addition, soluble forms predominated in the neurohypophysis and GPI-linked forms in the hypothalamus. Immunocytochemistry revealed a strong F3 immunoreactivity throughout the neurohypophysis and internal layer of the median eminence, characterized by a punctate labeling of fibers and dense filling of dilatations. In the hypothalamic nuclei, staining of variable intensity was visible in the cytoplasm of some magnocellular somata. In contrast, in colchicine-treated rats, all magnocellular somata throughout the hypothalamus displayed intense labeling while staining in the neurohypophysis was greatly reduced. Our observations reveal that neurons of the adult hypothalamo-neurohypophysial system express high level of F3, even under normal conditions. In view of its distribution and the differing proportions of membrane-bound and soluble forms, we propose that, after synthesis in the hypothalamus, F3 is targeted to the neurohypophysis where it accumulates in neurosecretory terminals or is released into the extracellular space. It remains to be seen whether its expression is linked to the secretion of the neurohypophysial peptides and in particular, to the ability of these neurons to undergo structural remodelling in adulthood.