Treatment strategy for severe trauma patients requiring aortic occlusion for impending cardiopulmonary arrest in the hybrid emergency room.

Aim: Computed tomography (CT) is useful in trauma care. Severely ill trauma patients may not tolerate whole-body CT even without patient transfer. This study examined clinical flow of severe trauma patients requiring aortic occlusion (AO) such as resuscitative thoracotomy or REBOA in the hybrid emergency room (ER) and investigated patient clinical courses prioritizing CT first versus resuscitation including AO first. Methods: This retrospective, single-center observational study included consecutive trauma patients visiting our ER between May 2016 and February 2023. Patients were divided into the CT first group (whole-body CT preceded AO) and AO first group (AO preceded whole-body CT) and into two subgroups: AO after CT (AO/interventions for hemorrhage performed just after CT in the CT first group), and CT after AO (CT or damage control surgery performed after AO in the AO first group). We investigated 28-day survival rates. Results: Survival probability by TRISS method was 49% (range: 3.3-94) in the CT first group (n = 6) and 20% (range: 0.7-45) in the AO first group (n = 7). Actual 28-day survival rates were 50% and 57%, respectively. Survival rates of the AO after CT subgroup (CT first group) were 75% (3/4) and 0% (0/2), respectively, and those of the CT after AO subgroup (AO first group) were 25% (1/4) and 100% (3/3), respectively. Conclusion: In severe trauma patients with low predicted probability of survival treated in the hybrid ER, survival rates might be better if resuscitation including AO is performed before CT and if damage control surgery is performed first before CT.

Thromboembolic complications during and after embolization of unruptured aneurysms: A chronological outcome in periprocedural thromboembolic events.

Background: Ischemic complications develop after elective coil embolization procedures at a certain rate. The prevention of these events has been a longstanding issue for many interventional neuroradiologists. This study aimed to clarify whether procedural ischemic events after unruptured aneurysm embolization decrease over time with perioperative anti-thromboembolic treatment or surgical experience. Methods: This study included patients with cerebral aneurysms in our institution between July 2012 and June 2020. Dual-antiplatelet therapy (DAPT) was performed (Phase 1). Thromboembolic events developed at a certain rate; thus, rivaroxaban was administered with single-antiplatelet therapy (SAPT) to improve thromboembolic results (Phase 2), showing better outcomes than in Phase 1. Subsequently, DAPT was administered again (Phase 3). Ischemic complications were evaluated in each phase or compared between the DAPT group and the direct oral anticoagulant (DOAC) with the clopidogrel (DOAC+SAPT) group. Results: Relatively, fewer symptomatic ischemic events were noted in Phase 2 or the DOAC+SAPT group, but the outcome was not better in Phase 3 than in Phase 2. Symptomatic complications were more common in Phase 3 than in Phases 1 and 2. Conclusion: Ischemic complications occurred at a certain rate after endovascular procedures for unruptured aneurysms. The incidence did not decrease over time; particularly, standard DAPT plus postoperative anti-thromboembolic medication did not adequately decrease complications in Phase 3 compared to Phases 1 and 2. Therefore, accumulated experience or a learning curve could not explain the results. DOAC administration might decrease the risk of these events, but further accumulation of evidence or prospective investigation is warranted.

Clinical experience of treatment of immunocompromised individuals with persistent SARS-CoV-2 infection based on drug resistance mutations determined by genomic analysis: a descriptive study.

BACKGROUND: The efficacy of antiviral drugs that neutralize antibody drugs and fight against SARS-COV-2 is reported to be attenuated by genetic mutations of the virus in vitro. When B-cell immunocompromised patients are infected with SARS-COV-2, the infection can be prolonged, and genetic mutations can occur during the course of treatment. Therefore, for refractory patients with persistent COVID-19 infection, genomic analysis was performed to obtain data on drug resistance mutations as a reference to determine which antiviral drugs and antibody therapies might be effective in their treatment. METHODS: This was a descriptive analysis with no controls. Patients were diagnosed as having COVID-19, examined, and treated in the Kansai Medical University General Medical Center between January 2022 and January 2023. The subjects of the study were B-cell immunocompromised patients in whom genome analysis of SARS-CoV-2 was performed. RESULTS: During the study period, 984 patients with COVID-19 were treated at our hospital. Of those, 17 refractory cases underwent genomic analysis. All 17 patients had factors related to immunodeficiency, such as malignant lymphoma or post-organ transplantation. Eleven patients started initial treatment for COVID-19 at our hospital, developed persistent infection, and underwent genomic analysis. Six patients who were initially treated for COVID-19 at other hospitals became persistently infected and were transferred to our hospital. Before COVID-19 treatment, genomic analysis showed no intrahost mutations in the NSP5, the NSP12, and the RBD regions. After COVID-19 treatment, mutations in these regions were found in 12 of 17 cases (71%). Sixteen patients survived the quarantine, but one died of sepsis. CONCLUSIONS: In genomic analysis, more mutations were found to be drug-resistant after COVID-19 treatment than before COVID-19 treatment. Although it was not possible to demonstrate the usefulness of genome analysis for clinical application, the change of the treatment drug with reference to drug resistance indicated by genomic analysis may lead to good outcome of immunocompromised COVID-19 patients.

Hybrid emergency room: Installation, establishment, and innovation in the emergency department.

A novel trauma workflow system called the hybrid emergency room (Hybrid ER) that combines a sliding computed tomography (CT) scanning system with interventional radiology features was first installed in Osaka General Medical Center in 2011. The Hybrid ER enables CT diagnosis and emergency therapeutic interventions without transferring the patient to another examination room. In this article, the history of CT in trauma care, the world's first installation of the Hybrid ER, clinical experiences, and evidence for the Hybrid ER in trauma workflow and nontrauma fields are summarized, and the future and innovation of the Hybrid ER are reviewed.

Peak value of serum KL-6 may be useful for predicting poor prognosis of severe COVID-19 patients.

BACKGROUND: Serum Krebs von den Lungen 6 (KL-6), which reflects alveolar epithelial injury, was reported to be useful to predict the progression of pneumonitis induced by COVID-19 in the early phase. This study aimed to evaluate the peak value of serum KL-6 during hospitalization for COVID-19 to discover a more useful biomarker for predicting prognosis in COVID-19 patients. METHODS: In this retrospective, single-center, observational study, we analyzed the data of 147 hospitalized patients who required supplemental oxygen, high-flow oxygen therapy, or invasive mechanical ventilation for respiratory failure due to COVID-19 from March 2020 to February 2021. We extracted data on patient sex, age, comorbidities, treatment, and biomarkers including the initial and peak values of KL-6. Inclusion criteria were examination of the studied biomarkers at least once within 3 days of admission, then at least once a week, and at a minimum, at least twice during the entire hospitalization. Area under the receiver operating curve (AUC) was analyzed to determine the accuracy of several biomarkers including KL-6 and LDH for predicting poor prognosis defined as survivors requiring invasive mechanical ventilation for over 28 days or non-survivors of COVID-19. Univariable and multivariate logistic regression analyses were performed to investigate the prognostic value of the baseline characteristics and biomarkers. RESULTS: Among the 147 patients, 108 (73.5%) had a good prognosis and 39 (26.5%) had a poor prognosis. The AUC analysis indicated that peak KL-6 showed precise accuracy in the discrimination of patients with poor prognosis (AUC 0.89, p < 0.001). The best cut-off value for KL-6 concentration was 966 U/mL (sensitivity 81.6%, specificity84.3%). After adjustment, increasing peak values of KL-6 or LDH were associated with a high risk of poor prognosis, with an adjusted odds ratio of 1.35 for peak value of KL-6, per 100 U/mL increase (95% CI 1.17-1.57, p < 0.001) and 2.16 for peak value of LDH, per 100 U/L increase (95% CI 1.46-3.20, p < 0.001). CONCLUSIONS: Peak values of KL-6 and LDH measured during hospitalization might help to identify COVID-19 patients with respiratory failure who are at higher risk for a poor prognosis.

Short-Vessel Occlusion Might Indicate Higher Possibility of Success in Reperfusion following Mechanical Thrombectomy in Acute Middle Cerebral Artery Occlusion.

BACKGROUND: The impact of the length of the occluded vessel in acute large-vessel occlusion on successful reperfusion by mechanical thrombectomy remains unclear. This study evaluated whether diameter and length of the occluded vessel in acute middle cerebral artery (MCA) occlusion might relate to successful reperfusion following mechanical thrombectomy. METHODS: This retrospective study included patients with acute MCA occlusion who underwent intra-aortic injection of contrast medium to obtain maximum intensity projection (MIP) images acquired by flat-panel detector computed tomography (FD-CT) equipped with an angiographic system. All patients received mechanical thrombectomy and were divided into two groups: those with successful reperfusion (Thrombolysis in Cerebral Infarction [TICI] 2b/3) and those without. We compared the diameter and length of the occluded vessel between the groups. In the sub-analysis of patients with stent retriever use, ratio of length of occluded vessel to length of the active zone was compared. RESULTS: We enrolled 29 patients (median age: 73, M1 occlusion: 51%, stent retriever use: 72%). Eighteen patients achieved TICI 2b/3 with significantly larger distal end diameter (1.7 [interquartile range: 1.5-1.9] vs. 1.2 [1.2-1.5] mm, p = 0.007) and shorter length (7.1 [4.9-9.7] vs. 12.3 [7.2-15.8] mm, p = 0.043) of the occluded vessel. Sub-analysis of 21 patients showed that the cut-off value for TICI 2b/3 reperfusion was 0.32 as the ratio between the occluded vessel and stent retriever active zone (receiver operating characteristic area under the curve: 0.90). CONCLUSION: In acute MCA occlusion, larger diameter of the distal end and shorter length of the occluded vessel on FD-CT MIP images might indicate a higher possibility of achieving TICI 2b/3 following mechanical thrombectomy.

Successful Mechanical Thrombectomy for Subocclusive Thrombus at the Origin of Lenticulostriate Artery.

Optimal treatment of patients with intracranial subocclusive thrombus remains unclear. Such a rare case successfully managed with endovascular mechanical thrombectomy is presented. A 71-year-old man experienced a sudden onset of dysarthria and motor deficits. At the time of admission his National Institutes of Health Stroke Scale (NIHSS) score was 4. DWI demonstrated incomplete infarction within the left lenticulostriate artery (LSA) territory, MRA showed partial flow defect in the distal left M1 segment and non-visualization of the LSA, and ECG revealed atrial fibrillation, thus ischemic stroke caused by cardiogenic embolism was diagnosed. Tissue plasminogen activator was administered, but symptoms progressed and NIHSS score increased up to 8. Diagnostic angiogrpahy confirmed presence of the subocclusive thrombus within the distal left M1 segment and complete occlusion of LSA at its origin. Since conservative therapy was ineffective, mechanical thrombectomy utilizing ADAPT (a direct aspiration first-pass thrombectomy) technique was performed resulting in compete recanalization of the LSA accompanied by the prompt regress of neurological symptoms. Eventally, the patient demonstrated nearly full recovery (modified Rankin Scale score 1). Thus, mechanical thrombectomy should be considered as a reasonable option in cases of acute cerebral stroke caused by subocclusive thrombus and progressive neurological deficits despite standard conservative therapy. J. Med. Invest. 67 : 372-374, August, 2020.

Intra-arterial infusion of fasudil hydrochloride to treat post-traumatic cerebral vasospasm.

BACKGROUND: The effect of intra-arterial infusion of fasudil hydrochloride in patients with post-traumatic cerebral vasospasm remains unclear. Here we report a case of intra-arterial infusion of fasudil hydrochloride for post-traumatic cerebral vasospasm. CASE PRESENTATION: A 47-year-old man was transferred to our hospital with a fractured skull and traumatic subarachnoid hemorrhage. As rhinorrhea of cerebrospinal fluid had not improved, repair surgery was carried out on day 4. Aphasia appeared on day 13. Magnetic resonance imaging and angiography showed an ischemic region in the left temporal lobe and vasospasm of the left middle cerebral artery. We immediately carried out angiography and diagnosed severe vasospasm of the M1 region of the left middle cerebral artery. After placing a microcatheter into the proximal middle cerebral artery, we injected fasudil hydrochloride intra-arterially. Vasospasm improved and aphasia resolved. CONCLUSION: In this case, intra-arterial infusion of fasudil hydrochloride was effective against post-traumatic cerebral vasospasm.

A case of curable dementia treated by effective endovascular embolization for dural arteriovenous fistula.

BACKGROUND: We report a case in which an effective endovascular treatment cured the worsening of dementia due to a dural arteriovenous fistula (dAVF). CASE REPORT: A 73-year-old woman suffered for 1.5 years from gait disturbance and disorientation that were suspicious of dementia. A brain MRI revealed that her symptoms were likely due to dAVF. An angiography provided a definitive diagnosis of dural transverse-sigmoid sinus fistula. Transvenous embolization completely occluded the fistula and led to a significant improvement of her cognitive function in tandem with a restoration of the cerebral blood flow. CONCLUSION: Endovascular treatment for dAVF is sometimes effective in treating worsening dementia, which might be due to the drastic change in cerebral blood flow in the area relevant to the cognitive function.

Memory impairment caused by cerebral hematoma in the left medial temporal lobe due to ruptured posterior cerebral artery aneurysm.

BACKGROUND: Cognitive disorders, such as memory disturbances, are often observed following a subarachnoid hemorrhage. We present a very rare case where rupture of a posterior cerebral artery aneurysm caused restricted damage to the hippocampus unilaterally, and caused memory disturbances. CASE PRESENTATION: A 56-year-old, right-handed man, with a formal education history of 16 years and company employees was admitted to our hospital because of a consciousness disturbance. He was diagnosed as having a subarachnoid hemorrhage due to a left posterior cerebral artery dissecting aneurysm, and coil embolization was performed. Subsequently, he had neither motor paresis nor sensory disturbances, but he showed disorientation, and both retrograde and anterograde amnesia. Although immediate recall and remote memory were almost intact, his recent memory was moderately impaired. Both verbal and non-verbal memories were impaired. Brain computed tomography (CT) and magnetic resonance imaging (MRI) revealed a cerebral hematoma in the left temporal lobe involving the hippocampus and parahippocampal gyrus, and single-photon emission computed tomography (SPECT) demonstrated low perfusion areas in the left medial temporal lobe. CONCLUSIONS: We suggest that the memory impairment was caused by local tissue destruction of Papez's circuit in the dominant hemisphere due to the cerebral hematoma.

Retrosplenial amnesia without topographic disorientation caused by a lesion in the nondominant hemisphere.

We report the case of a 68-year-old right-handed man who was admitted to our hospital because of sudden onset of headache. On admission, he presented with left homonymous hemianopsia, disorientation, and recent memory disturbance; however, he had normal remote memory and digit span. He was able to recall the room layout of his house and describe the route from the nearest station to his home on a map. However, at the hospital, he sometimes lost his way because of amnesia. Computed tomography (CT) and magnetic resonance imaging revealed a subcortical hematoma in the right occipital forceps and the parietal lobe, involving the cingulate isthmus. Single-photon emission CT imaging showed reduced perfusion not only in the retrosplenial region but also in the right thalamus. These findings suggested that the retrosplenial amnesia might have been caused by the interruption of hippocampal input into the anterior thalamus.

Significance of urinary incontinence, age, and consciousness level on arrival among patients with stroke.

PURPOSE: We retrospectively investigated prognostic factors including urinary incontinence on arrival among the patients with stroke. MATERIALS AND METHODS: A medical chart review was retrospectively performed for patients with stoke admitted between January 2010 and December 2010 in Ken-o Tokorozawa Hospital which had stroke care unit. The subjects were divided into a control group (functional outcome with modified Rankin scale (mRS) 0-3 at 3 months) and a poor group (severe disability or death, mRS 4-6). RESULTS: There were 160 cases that had favorable outcome (the Control group) and 77 cases that had poor outcome (the Poor group). There were no significant differences between the two groups concerning the sex ratio, systolic blood pressure, heart rate, temperature, ratio of diabetes mellitus. However, the average age, ratio of hemorrhagic stroke, ratio of patients with a previous stroke, ratio of urinary incontinence upon admission, and duration of hospitalization in the Poor group was significantly higher than in the Control group. The Glasgow Coma Scale upon admission and ratio of hypertension in the Poor group were significantly lower than that in the Control group. Using a multiple logistic regression analysis, urinary incontinence (odds ratio, 3.17; 95% confidence interval, 1.45-6.93; P = 0.002), age (odds ratio, 1.04; 95% confidence interval, 1.01-1.07; P = 0.003) and Glasgow Coma Scale (odds ratio, 0.87; 95% confidence interval, 0.78-0.97; P = 0.01) were found to be factors independently associated with a poor outcome. CONCLUSION: Among the patients with strokes, the presence of urinary incontinence on arrival, the old age, and the level of consciousness are important prognostic factors. Physicians should therefore check for these factors when evaluating a patient who has experienced a stroke or suspected stroke.

Agraphia caused by left thalamic hemorrhage.

A 71-year-old right-handed man was admitted to our hospital with right hemiparesis and sensory impairment associated with mild aphasia. Although aphasia gradually resolved within 2 weeks after stroke onset, his writing ability remained disturbed. A computed tomography (CT) scan at stroke onset revealed a hematoma in the left thalamus, but no cortical lesions were observed. Further, a single-photon emission CT (SPECT) scan showed decreased blood flow in the left thalamus, in the cortical region extending from the left superior temporal gyrus to the parietal lobe, and in the frontal lobe. It is possible that agraphia may have directly resulted from the thalamic lesion, but SPECT findings strongly suggested that a general decrease in left cortical function concomitant with a disruption of the thalamocortical and cortico-thalamocortical projection fibers produced these cognitive deficits.

A patient with demyelination, laminar cortical necrosis, and rhabdomyolysis associated with hypernatremia.

A 60-year-old man with renal failure and intraabdominal abscess formation probably due to perforation of the colon underwent laparotomy on the sixth hospital day. He developed respiratory infection, deterioration of renal failure, and heart failure resulting in severe respiratory insufficiency after laparotomy. He was placed on mechanical ventilation using sedatives and muscle relaxant and was treated with antibiotics, steroids, and a diuretic. The value of serum sodium jumped from 146 to 164 mEq/L in 2 days. Sodium infusion was discontinued, and hypernatremia decreased. He fell into a coma and demonstrated generalized convulsions after mechanical ventilation was discontinued. His head computed tomography did not indicate any pathologic findings, and his convulsions were not controlled so that he was again placed on mechanical ventilation. The laboratory findings revealed rhabdomyolysis (18936 IU/L) 5 days after the normalization of hypernatremia. Mechanical ventilation and hemodialysis were terminated after the convulsions were controlled and the renal failure improved on the 82nd hospital day. Head magnetic resonance imaging exhibited that multiple hyperintensity lesions in the white matter with linear signal changes in both occipital cortex. He remained unconscious for 6 months. This is the first case that demonstrated demyelination, laminar cortical necrosis, and rhabdomyolysis associated with hypernatremia. Rhabdomyolysis after rapid occurrence of hypernatremia might be a laboratory sign of concomitant demyelination.

Transplantation of cultured choroid plexus epithelial cells via cerebrospinal fluid shows prominent neuroprotective effects against acute ischemic brain injury in the rat.

Choroid plexus (CP) epithelial cells (CPECs) produce cerebrospinal fluid (CSF) to provide the CNS with a specialized microenvironment. Our previous study showed that the conditioned medium of cultured CPECs enhanced the survival and neurite extension of hippocampal neurons. The present study examined the ability of cultured CPECs to protect against ischemic brain injury when transplanted into the CSF. Rats were subjected to a transient occlusion of the middle cerebral artery, followed by an injection of cultured CPECs into the fourth ventricle. The injection markedly reduced neurological deficits and infarction volume within 24h. Other beneficial effects were (1) a reduction in number of apoptotic and inflammatory cells, (2) an up-regulation of the mRNA expression of an anti-apoptotic effecter, cAMP-response element binding protein, and (3) a down-regulation of the production of pro-inflammatory factors such as interleukin-1 beta and inducible nitric oxide synthase. The injected CPECs were located within the ventricles and on the brain's surface, not in the ischemic foci, suggesting that they exert their effects by releasing diffusible neuroprotective factors into the CSF. The transplantation of CPECs via CSF is a potential new strategy for protecting against ischemic brain injury.

Increase in circulating CD34-positive cells in patients with angiographic evidence of moyamoya-like vessels.

Increasing evidence points to a role for circulating endothelial progenitor cells, including populations of CD34-positive (CD34(+)) cells, in maintenance of cerebral blood flow. In this study, we investigated the link between the level of circulating CD34(+) cells and neovascularization at ischemic brain. Compared with control subjects, a remarkable increase of circulating CD34(+) cells was observed in patients with angiographic moyamoya vessels, although no significant change was observed in patients with major cerebral artery occlusion (or severe stenosis) but without moyamoya vessels. Our results suggest that the increased level of CD34(+) cells associated with ischemic stress is correlated with neovascularization at human ischemic brain.

Granulocyte colony-stimulating factor has a negative effect on stroke outcome in a murine model.

The administration of CD34-positive cells after stroke has been shown to have a beneficial effect on functional recovery by accelerating angiogenesis and neurogenesis in rodent models. Granulocyte colony-stimulating factor (G-CSF) is known to mobilize CD34-positive cells from bone marrow and has displayed neuroprotective properties after transient ischemic stress. This led us to investigate the effects of G-CSF administration after stroke in mouse. We utilized permanent ligation of the M1 distal portion of the left middle cerebral artery to develop a reproducible focal cerebral ischemia model in CB-17 mice. Animals treated with G-CSF displayed cortical atrophy and impaired behavioral function compared with controls. The negative effect of G-CSF on outcome was associated with G-CSF induction of an exaggerated inflammatory response, based on infiltration of the peri-infarction area with CD11b-positive and F4/80-positive cells. Although clinical trials with G-CSF have been started for the treatment of myocardial and limb ischemia, our results indicate that caution should be exercised in applying these results to cerebral ischemia.

Neuroprotective effect of bone marrow-derived mononuclear cells promoting functional recovery from spinal cord injury.

Neural cell transplantation, a new therapeutic strategy for replacing injured neural components and obtaining functional recovery, has shown beneficial effects in animal models. Use of this strategy in human patients, however, requires that a number of serious issues be addressed, including ethics, immunorejection, and the therapeutic time window within which the procedure will be effective. Bone marrow-derived mononuclear cells (BM-MNC) are attractive for transplantation because they can be used as an autograft, can be easily collected within a short time period, and do not have to be cultured. In a rat model of spinal cord injury (SCI), we transplanted BM-MNC at 1 h after SCI at Th 8-9 by injecting them into the cerebrospinal fluid (CSF), and investigated the effect of this on neurologic function. In the acute stage of injury, we found a neuroprotective antiapoptotic effect, with an elevated concentration of hepatocyte growth factor in CSF. At 1 week after transplantation, the Basso-Beattie-Bresnahan locomotor score had increased significantly over its base-line value. In the chronic stage of injury, we observed suppressed cavity formation and functional improvement. We conclude that transplantation of BM-MNC after SCI has a remarkable neuroprotective effect in the acute stage of injury, suppressing cavity formation, and contributing to functional recovery. Our results suggest that transplantation of BM-MNC via the CSF is a potentially effective means of enhancing functional recovery after SCI in humans.

Bone marrow stromal cells generate muscle cells and repair muscle degeneration.

Bone marrow stromal cells (MSCs) have great potential as therapeutic agents. We report a method for inducing skeletal muscle lineage cells from human and rat general adherent MSCs with an efficiency of 89%. Induced cells differentiated into muscle fibers upon transplantation into degenerated muscles of rats and mdx-nude mice. The induced population contained Pax7-positive cells that contributed to subsequent regeneration of muscle upon repetitive damage without additional transplantation of cells. These MSCs represent a more ready supply of myogenic cells than do the rare myogenic stem cells normally found in muscle and bone marrow.

Conditioned medium of the primary culture of rat choroid plexus epithelial (modified ependymal) cells enhances neurite outgrowth and survival of hippocampal neurons.

The choroid plexus epithelial (modified ependymal) cells (CPECs) are specialized for cerebrospinal fluid (CSF) production and serve as blood-CSF barrier. It is suggested that, in addition to CSF production, the CPECs may regulate CNS function through expression of secretory factors into CSF. There have been reports that the CPECs express various types of factors including growth factors. However, the actual effects of the molecules produced and secreted from the CPECs on the central nervous system (CNS) are virtually unknown both in vivo and in vitro. With the use of pure culture of CPECs, we demonstrated that the conditioned medium (CM) from CPECs can enhance neurite outgrowth and survival of cultured neurons derived from rat hippocampus on postnatal day 1 in 24-h cultures. The effect of the CM was retained in fractions that contains complex of molecules larger than 50kDa in native condition with ultrafiltration method and disappeared by trypsin digestion. The results of the present study indicate that CPECs can support the survival and function of neurons in vitro by secreting factors that are likely to be of peptide/protein nature rather than small chemicals.