The impact of palliative radiotherapy on health-related quality of life in patients with head and neck cancer - Results of a multicenter prospective cohort study

Purpose

Palliative radiotherapy for patients with head and neck cancer can be used to alleviate symptoms. Only a few studies have investigated its impact on patient-reported outcomes (PRO). Therefore, we conducted a prospective multicenter observational study. The primary objective was to assess changes in health-related quality of life (HrQoL) per PRO.

Methods

Eligibility criteria included i.) head and neck cancer and ii.) palliative radiotherapy indicated (EQD_2Gy < 60 Gy). The primary follow-up date was eight weeks after radiotherapy (t_8w). PRO measures included the EORTC QLQ-C30 and EORTC QLQ-H&N43 and pain per Numeric Rating Scale (NRS). Per protocol, five PRO domains were to be reported in detail as well as PRO domains corresponding to a primary and secondary symptom as determined by the individual patient. We defined a minimal important difference (MID) of 10 points.

Results

From 06/2020 to 06/2022, 61 patients were screened and 21 patients were included. Due to death or decline in health-status, HrQoL data was available for 18 patients at the first fraction and for eight patients at t_8w. The MID was not met for the predefined domains in terms of mean values as compared from first fraction to t_8w. Individually in those patients with available HrQoL data at t_8w, 71% (5/7) improved in their primary and 40% (2/5) in their secondary symptom domain reaching the MID from first fraction to t_8w, respectively. There was a significant improvement in pain per NRS in those patients with available data at t_8w per Wilcoxon signed rank test (p = 0.041). Acute mucositis of grade ≥3 per CTCAE v5.0 occurred in 44% (8/18) of the patients. The median overall survival was 11 months.

Conclusion

Despite low patient numbers and risk of selection bias, our study shows some evidence of a benefit from palliative radiotherapy for head and neck cancer as measured by PRO.German Clinical Trial Registry identifier: DRKS00021197.

Meeting report of the first conference of the International Placenta Stem Cell Society (IPLASS)

The International Placenta Stem Cell Society (IPLASS) was founded in June 2010. Its goal is to serve as a network for advancing research and clinical applications of stem/progenitor cells isolated from human term placental tissues, including the amnio-chorionic fetal membranes and Wharton's jelly. The commitment of the Society to champion placenta as a stem cell source was realized with the inaugural meeting of IPLASS held in Brescia, Italy, in October 2010. Officially designated as an EMBO-endorsed scientific activity, international experts in the field gathered for a 3-day meeting, which commenced with "Meet with the experts" sessions, IPLASS member and board meetings, and welcome remarks by Dr. Ornella Parolini, President of IPLASS. The evening's highlight was a keynote plenary lecture by Dr. Diana Bianchi. The subsequent scientific program consisted of morning and afternoon oral and poster presentations, followed by social events. Both provided many opportunities for intellectual exchange among the 120 multi-national participants. This allowed a methodical and deliberate evaluation of the status of placental cells in research in regenerative and reparative medicine. The meeting concluded with Dr. Parolini summarizing the meeting's highlights. This further prepared the fertile ground on which to build the promising potential of placental cell research. The second IPLASS meeting will take place in September 2012 in Vienna, Austria. This meeting report summarizes the thought-provoking lectures delivered at the first meeting of IPLASS.

Xenogeneic transplantation of equine testicular cells into seminiferous tubules of immunocompetent rats

The objectives were to develop a transplantation assay for equine testicular cells using busulfan-treated prepubertal immunocompetent rats as recipients, and to determine if putative equine spermatogonial stem cells (SSCs) could be enriched by flow cytometric cell sorting (based on light scattering properties), thereby improving engraftment efficiency. Four weeks after transplantation of frozen/thawed PKH26-labeled equine testicular cells, 0.029 ± 0.045% (mean ± SD) of viable donor cells transplanted had engrafted. Donor cells were present in seminiferous tubules of all recipient rats forming chains, pairs, mesh structures, or clusters (with two to >30 cells/structure). Cells were localized to the basal compartment by the basement membrane. Although equine cells proliferated within rat seminiferous tubules, no donor-derived spermatogenesis was evident. Furthermore, there was no histologic evidence of acute cellular rejection. No fluorescent cells were present in control testes. When equine testicular cells were sorted based on light scattering properties, the percentage of transplanted donor cells that engrafted was higher after injection of cells from the small, low complexity fraction (II; 0.169 ± 0.099%) than from either the large, high complexity fraction (I; 0.046 ± 0.051%) or unsorted cells (0.009 ± 0.007%; P < 0.05). Seminiferous tubules of busulfan-treated prepubertal immunocompetent rats provided a suitable niche for engraftment and proliferation, but not differentiation, of equine testicular cells. Sorting equine testicular cells based on light scattering properties resulted in a 19-fold improvement in colonization efficiency by cells with high forward scatter and low side scatter, which may represent putative equine SSCs.

Development of human umbilical cord matrix stem cell-based gene therapy for experimental lung tumors

Umbilical cord matrix stem (UCMS) cells are unique stem cells derived from Wharton's jelly, which have been shown to express genes characteristic of primitive stem cells. To test the safety of these cells, human UCMS cells were injected both intravenously and subcutaneously in large numbers into severe combined immunodeficiency (SCID) mice and multiple tissues were examined for evidence of tumor formation. UCMS cells did not form gross or histological teratomas up to 50 days posttransplantation. Next, to evaluate whether UCMS cells could selectively engraft in xenotransplanted tumors, MDA 231 cells were intravenously transplanted into SCID mice, followed by intravenous transplantation of UCMS cells 1 and 2 weeks later. UCMS cells were found near or within lung tumors but not in other tissues. Finally, UCMS cells were engineered to express human interferon beta--designated 'UCMS-IFN-beta'. UCMS-IFN-beta cells were intravenously transplanted at multiple intervals into SCID mice bearing MDA 231 tumors and their effect on tumors was examined. UCMS-IFN-beta cells significantly reduced MDA 231 tumor burden in SCID mouse lungs indicated by wet weight. These results clearly indicate safety and usability of UCMS cells in cancer gene therapy. Thus, UCMS cells can potentially be used for targeted delivery of cancer therapeutics.

Transplantation of pig stem cells into rat brain: proliferation during the first 8 weeks

Previous work indicated that pig umbilical cord matrix (pUCM) cells are a type of primitive stem cell and that these cells could be recovered after central or peripheral injection into rats that did not receive immune suppression therapy. To determine the safety and proliferation potential of pUCM cells after brain transplantation, approximately 150 pUCM cells were transplanted into the brains of rats that previously received a striatal injection of the neurotoxin 6-hydroxydopamine (6-OHDA). The pUCM cells were previously engineered to express enhanced green fluorescent protein (eGFP); in this way, the graft cells were identified. The rats did not receive immune suppression therapy. There were no postsurgical complications and the animals thrived following transplantation. At 2, 4, 6, and 8 weeks after transplantation, two rats were sacrificed and the morphology, size and number of graft cells, and the percentage of tyrosine hydroxylase (TH)-positive graft cells were determined. The size distribution of the grafted pUCM cells was unimodal and normal, and the average size increased significantly over the 2- to 8-week survival period. The number of pUCM cells increased from approximately 5400 cells at the 2-week survival period post-transplantation to approximately 20,000 cells at the 8-week survival period. There was an increase in the percentage of TH-positive pUCM cells from approximately 1% at the 2-week survival period to approximately 6% at the 8-week survival period. There was no evidence of a significant host immune response at any time; for example, no accumulation of CD-4, CD-8, CD-11b, CD-161 cells in the transplantation site. These results suggest that pUCM cells engraft and proliferate without requiring immune suppression. These findings also suggest that a subset of pUCM cells can differentiate into TH-positive cells within 8 weeks after transplantation into the 6-OHDA lesioned rat brain.

Weight gain after transjugular intrahepatic portosystemic shunt is associated with improvement in body composition in malnourished patients with cirrhosis and hypermetabolism

BACKGROUND/AIMS

To search for changes in body composition and energy metabolism associated with the repeatedly observed weight gain of cirrhotic patients after portosystemic shunting.

METHODS

Twenty-one patients were studied prospectively before and 6 and 12 months after transjugular intrahepatic portosystemic shunt (TIPS) to assess body cell mass by two independent methods (total body potassium counting: body cell mass determined by TBP, BCMTBP, bioelectric impedance analysis: body cell mass determined by BIA, BCMBIA), muscle mass (anthropometry), resting energy expenditure (REECALO) by indirect calorimetry, and nutritional intake by dietary recall analysis.

RESULTS

Prior to TIPS patients were hypermetabolic in terms of measured vs. predicted REE (REECALO median 1423 (range 1164-1838) vs. REEPRED 1279 (1067-1687) kcal; P<0.05) and their body cell mass was lower (19.1 (10.9-33.4) vs. 31.7 (16.8-47.1) kg; P=0.001). After TIPS body cell mass (BCMBIA) increased to 23.5 (12.7-44.3) (P<0.025) and 25.7 (14.2-39.7) kg (P=0.05) at 6 and 12 months after TIPS and this was confirmed by total potassium counting (BCMTBP before TIPS: 18.8 (10.6-26.7) vs. 22.4 (12.9-28.5) kg at 6 months; P<0.01). Hypermetabolism persisted throughout the study period. Energy and protein intake increased significantly by 26 and 33%.

CONCLUSIONS

An increase of prognostically relevant variables body cell and muscle mass contributes to the weight gain after TIPS in malnourished patients with cirrhosis and hypermetabolism.

Normal anatomical and histochemical characteristics of the lacrimal glands in the American bison and cattle

Dorsal lacrimal glands, superior glands of the third eyelid and Harderian glands (deep gland of the third eyelid) from 19 bison and 18 cattle free of apparent ocular disease were examined to compare the normal anatomical properties of these glands. All glands were characterized and measured (length and width). The gross anatomy of the dorsal lacrimal glands was similar, with the exception of a bipartite gland in cattle. The bison's superior gland of the third eyelid and Harderian gland was longer as compared with cattle. A subset of the bison and cattle samples (five bison and five cattle) was sectioned for histological and histochemical analysis. The histology of the dorsal lacrimal and superior gland of the third eyelid revealed tubuloalveolar cells with basophilic vacuolated cytoplasm in bison and eosinophilic granular cytoplasm in cattle. The Harderian glands consisted of a tubuloalveolar anterior part combined with large lumens acini lined with cuboidal epithelium in the posterior part; the posterior part of the bison Harderian gland was more predominant than in cattle samples. Mucosubstance histochemistry revealed acidic and neutral glycoproteins with similar staining patterns in all glands of both species.

Transplantation of porcine umbilical cord matrix cells into the rat brain

Immune rejection of transplanted material is a potential complication of organ donation. In response to tissue transplantation, immune rejection has two components: a host defense directed against the grafted tissue and an immune response from the grafted tissue against the host (graft vs host disease). To treat immune rejection, transplant recipients are typically put on immunosuppression therapy. Complications may arise from immune suppression or from secondary effects of immunosuppression drugs. Our preliminary work indicated that stem cells may be xenotransplanted without immunosuppression therapy. Here, we investigated the survival of pig stem cells derived from umbilical cord mucous connective tissue (UCM) after transplantation into rats. Our data demonstrate that UCM cells survive at least 6 weeks without immune suppression of the host animals after transplantation into either the brain or the periphery. In the first experiment, UCM cells were transplanted into the rat brain and recovered in that tissue 2-6 weeks posttransplantation. At 4 weeks posttransplantation, the UCM cells engrafted into the brain along the injection tract. The cells were small and roughly spherical. The transplanted cells were positively immunostained using a pig-specific antibody for neuronal filament 70 (NF70). In contrast, 6 weeks posttransplantation, about 10% of the UCM cells that were recovered had migrated away from the injection site into the region just ventral to the corpus callosum; these cells also stained positively for NF70. In our second experiment, UCM cells that were engineered to constitutively express enhanced green fluorescent protein (eGFP) were transplanted. These cells were recovered 2-4 weeks after brain transplantation. Engrafted cells expressing eGFP and positively staining for NF70 were recovered. This finding indicates a potential for gene therapy. In the third experiment, to determine whether depositing the graft into the brain protected UCM cells from immune detection/clearance, UCM cells were injected into the tail vein and/or the semitendinosis muscle in a group of animals. UCM cells were recovered from the muscle or within the kidney 3 weeks posttransplantation. In control experiments, rat brains were injected with PKH 26-labeled UCM cells that had been lysed by repeated sonic disruption. One and 2 weeks following injection, no PKH 26-labeled neurons or glia were observed. Taken together, these data indicate that UCM cells can survive xenotransplantation and that a subset of the UCM cells respond to local signals to differentiate along a neural lineage.

Incorporation of bovine bone marrow stromal cells into porcine foetal tissues after xenotransplantation

Bovine bone marrow stromal cells (BMSCs) were injected into the liver of foetal pigs at about 40 days of gestation to test whether these cells could populate developing tissue, and if so, which ones. Approximately 40 days after injection, the foetuses were harvested and tissue sections from many areas of the body were analysed for the presence of bovine cells using two different methods. First, using PCR, bovine repetitive DNA was found to be present in DNA extracted from foetal pig tissues. Secondly, using oligonucleotide primed in situ synthesis (PRINS), the in situ presence of bovine cells was found within porcine tissue sections. PRINS-labelled cells were found within cartilage, perichondrium, connective tissue and smooth muscle. These data suggest that bovine BMSCs integrate throughout the foetal pig.

The paraventricular nucleus: an important component of the central neurocircuitry regulating sympathetic nerve outflow

AIM

The sympathetic nervous system plays an important role in the regulation of physiological homeostasis under basal conditions and in response to acute and chronic stressors. It is known that multiple levels of the neuroaxis, including the paraventricular nucleus (PVN) of the hypothalamus, are involved in regulation of efferent sympathetic nerve discharge (SND). This review focuses on the role of the PVN in regulation of functional characteristics of efferent SND.

RESULTS

The available experimental evidence indicates that the level of efferent sympathetic nerve activity is altered after microinjection of numerous substances into the PVN, including excitatory amino acids, gamma-aminobutyric acid (GABAA) receptor agonists and antagonists, and PVN nitric oxide synthase inhibitors. In addition, antagonism of PVN GABAA receptors changes the pattern of synchronized discharge bursts in efferent sympathetic nerves and enhances the frequency-domain coupling between low-frequency bursts in sympathetic nerve pairs. Finally, PVN microinjections of excitatory amino acids (L-glutamate, D,L-homocysteic acid) have been shown to produce non-uniform changes in the level of efferent sympathetic nerve activity.

CONCLUSION

These findings support the concept that the PVN is an important component of the central neurocircuitry regulating functional characteristics (basal level of activity, bursting pattern, and relationships between discharges in nerves innervating different targets) of efferent sympathetic nerve outflow.

Modifications to central neural circuitry during heart failure

AIM

During heart failure (HF), excess sodium retention is triggered by increased plasma renin-angiotensin-aldosterone activity and increased basal sympathetic nerve discharge (SND). Enhanced basal SND in the renal nerves plays a role in sodium retention. Therefore, as a hypothetical model for the central sympathetic control pathways that are dysregulated as a consequence of HF, the central neural pathways regulating the sympathetic motor output to the kidney are reviewed in the context of their role during HF.

CONCLUSION

From these findings, a model of the neuroanatomical circuitry that may be affected during HF is constructed.

Bovine herpesvirus 5 (BHV-5) Us9 is essential for BHV-5 neuropathogenesis

Bovine herpesvirus 5 (BHV-5) is a neurovirulent alphaherpesvirus that causes fatal encephalitis in calves. In a rabbit model, the virus invades the central nervous system (CNS) anterogradely from the olfactory mucosa following intranasal infection. In addition to glycoproteins E and I (gE and gI, respectively), Us9 and its homologue in alphaherpesviruses are necessary for the viral anterograde spread from the presynaptic to postsynaptic neurons. The BHV-5 Us9 gene sequence was determined, and the predicted amino acid sequence of BHV-5 Us9 was compared with the corresponding Us9 sequences of BHV-1.1. Alignment results showed that they share 77% identity and 83% similarity. BHV-5 Us9 peptide-specific antibody recognized a doublet of 17- and 19-kDa protein bands in BHV-5-infected cell lysates and in purified virions. To determine the role of the BHV-5 Us9 gene in BHV-5 neuropathogenesis, a BHV-5 Us9 deletion recombinant was generated and its neurovirulence and neuroinvasive properties were compared with those of a Us9 rescue mutant of BHV-5 in a rabbit model. Following intranasal infection, the Us9 rescue mutant of BHV-5 displayed a wild-type level of neurovirulence and neural spread in the olfactory pathway, but the Us9 deletion mutant of BHV-5 was virtually avirulent and failed to invade the CNS. In the olfactory mucosa containing the olfactory receptor neurons, the Us9 deletion mutant virus replicated with an efficiency similar to that of the Us9 rescue mutant of BHV-5. However, the Us9 deletion mutant virus was not transported to the bulb. Confocal microscopy of the olfactory epithelium detected similar amounts of virus-specific antigens in the cell bodies of olfactory receptor neuron for both the viruses, but only the Us9 rescue mutant viral proteins were detected in the processes of the olfactory receptor neurons. When injected directly into the bulb, both viruses were equally neurovirulent, and they were transported retrogradely to areas connected to the bulb. Taken together, these results indicate that Us9 is essential for the anterograde spread of the virus from the olfactory mucosa to the bulb.

Silver-haired bat rabies virus variant does not induce apoptosis in the brain of experimentally infected mice

To examine whether induction of apoptosis plays a role in the pathogenesis of street rabies, we compared the distribution of viral antigens, histopathology, and the induction of apoptosis in the brain of mice infected with a street rabies virus (silver-haired bat rabies virus, SHBRV) and with a mouse-adapted laboratory rabies virus strain (challenge virus standard, CVS-24). Inflammation was identified in the meninges, but not in the parenchyma of the brain of mice infected with either CVS-24 or SHBRV. Necrosis was present in numerous cortical, hippocampal, and Purkinje neurons in CVS-24-infected mice, but only minimal necrosis was identified in mice infected with SHBRV. Likewise, extensive terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL) staining was observed in the brain of mice infected with CVS-24 but little or none in the brain of mice infected with SHBRV. Rabies virus antigens were distributed similarly in the CNS infected with either virus. However, the expression of the glycoprotein (G) is more widespread and the staining of G is generally stronger in CVS- than SHBRV-infected mice, whereas the expression of rabies virus nucleoprotein (N) is similar in mice infected with either CVS or SHBRV. The positive TUNEL staining thus correlates with the high level of G expression in CVS-infected mouse brain. Northern blot hybridization revealed that the ratio between the N and G transcripts is similar in brains infected with either virus, indicating that the reduced expression of G protein is not caused by reduced transcription in SHBRV-infected animals. Taken together, these observations suggest that apoptosis is not an essential pathogenic mechanism for the outcome of a street rabies virus infection and that other pathologic processes may contribute to the profound neuronal dysfunction characteristic of street rabies.

Neural circuitry of the kidney: NO-containing neurons

The neurons synthesizing nitric oxide (NO) that are part of the renal sympathetic pathways were located by double-staining for the neuronal isoform of nitric oxide synthase (nNOS) using immunocytochemistry to identify NO-synthesizing neurons and transneuronal tracing following infection of the left kidney with pseudorabies virus (PRV). Following kidney injection with PRV, the animals survived 4-day post-inoculation prior to sacrifice and tissue processing. PRV-infected neurons that double-stained for nNOS were found in the paraventricular hypothalamic nucleus (PVN), the raphe obscurus nucleus (ROb), the ventromedial medulla (VMM), the rostral ventrolateral medulla (rVLM) and the A5 cell group. In the thoracolumbar spinal cord, nNOS neurons co-localized with PRV-infected cells in the dorsal horn in laminae I, III-V ipsilateral to the injected kidney and in lamina X, the intermediolateral cell column, the lateral funiculus, the intercalated nucleus and the central autonomic area. We conclude that NO synthesizing cells may significantly affect renal autonomic pathways in the rat by interacting with the renal sensory and sympathomotor circuitry at multiple sites.

Paraventricular nucleus bicuculline alters frequency components of sympathetic nerve discharge bursts

Autospectral and coherence analyses were used to determine the effect of paraventricular nucleus (PVN) GABA(A) receptor antagonism [microinfusion or microinjections of bicuculline methiodide (BMI) 100 pmoles] on sympathetic nerve discharge (SND) frequency components (bursting pattern and relationships between discharges in regionally selective nerves) in alpha-chloralose-anesthetized rats. SND was recorded from the renal, splenic, and lumbar nerves. The following observations were made. First, PVN BMI microinjections, but not PVN saline or cortical BMI microinjections, transformed the cardiac-related SND bursting pattern in baroreceptor-innervated rats to one characterized by the presence of low-frequency bursts not synchronized to the cardiac cycle or phrenic nerve discharge bursts. Second, SND pattern changes were similar in the renal, splenic, and lumbar nerves, and peak coherence values relating low-frequency bursts in sympathetic nerve pairs (renal-splenic, renal-lumbar, and splenic-lumbar) were significantly increased from preinjection control after PVN BMI microinjection. Third, PVN BMI microinjections significantly increased the coupling between low-frequency SND bursts in baroreceptor-denervated rats. Finally, PVN BMI-induced changes in the SND bursting pattern were not observed after PVN pretreatment with muscimol (GABA agonist, 1 nmole). We conclude that PVN GABA(A) receptor antagonism profoundly alters the frequency components in sympathetic nerves.

Renal sympathetic nerve regulation to heating is altered in rats with heart failure

Heart failure (HF) alters the regulation of basal sympathetic nerve discharge (SND); however, the effect of HF on SND responses to acute stress is not well established. In the present study, renal SND responses to hyperthermia were determined in chloralose-anesthetized HF rats and in sham controls. Whole body heating (colonic temperature increased from 38 to 41 degrees C) was used as an acute stressor because increased internal body temperature provides a potent stimulus to the sympathetic nervous system. Left ventricular end-diastolic pressure and the right ventricular wt-to-body wt ratio were increased (P < 0.05) in HF compared with sham rats. The following observations were made: 1) renal sympathoexcitatory responses to heating were significantly reduced in HF compared with sham rats, 2) renal blood flow remained unchanged from control levels during heating in HF rats but was significantly reduced in sham rats, and 3) renal SND responses to heating were significantly higher in HF rats with bilateral lesions of the hypothalamic paraventricular nucleus (PVN) compared with sham PVN-lesioned HF rats. These results demonstrate a marked attenuation in the responsiveness of renal SND to heating in HF rats and suggest that HF alters the organization of neural pathways mediating SND responses to heating.

The estrous cycle affects pseudorabies virus (PRV) infection of the CNS

Previous work had suggested that mucosal immunity may be affected by the stage of the estrous cycle. Here, susceptibility to a neurotropic virus infection at different stages of the estrous cycle was assessed in a rodent model after direct injection of the virus into visceral organs. In the first two experiments, female Sprague-Dawley rats were infected with pseudorabies virus (PRV, Bartha's K-strain) by injection into either the cervix or the kidney after monitoring their estrous cycle. After either 4- or 5-day survival period post-infection, the rats were euthanized by transcardially perfusion and peripheral and central nervous system tissues were removed for immunocytochemical staining. The number of infected neurons was counted in various regions. Statistical analysis revealed that: (1) the number of infected cells in the sympathetic or parasympathetic ganglion, or the dorsal root ganglia was not affected regardless of the stage of the estrous cycle after cervix injection with PRV; (2) in contrast, the number of infected neurons in the spinal cord was affected significantly by the stage of the estrous cycle during viral infection of the cervix; (3) after kidney infection, the number of infected neurons found within the spinal cord or dorsal root ganglia varied significantly across the estrous cycle. In both cases, animals infected in proestrus or estrus had fewer infected neurons than animals infected in diestrus I or diestrus II (proestrous and estrous animals had less than 20% of infected cells found in diestrus I or diestrus II rats). In the third experiment, older, persistent estrous or persistent diestrous rats were infected by kidney injection and given a 4-day survival period, prior to virus isolation from lower thoracic spinal cord. Animals in persistent estrous had significantly less virus per gram of tissue than the persistent diestrous rats. These data suggest that the CNS of animals in proestrus or estrus is less susceptible to PRV infection compared to animals in either diestrus I or diestrus II. Because estrogen replacement therapy is known to restore some immune functions during reproductive ageing, it is speculated that plasma estrogen levels modulate the central nervous system's susceptibility to viral infections.

Bioelectrical impedance analysis is a useful bedside technique to assess malnutrition in cirrhotic patients with and without ascites

Protein-calorie malnutrition is associated with poor prognosis in chronic liver disease, but reliable assessment is hampered by changes in body water. We prospectively evaluated the effect of fluid retention on bioelectrical impedance analysis (BIA) as a simple method for the estimation of body cell mass (BCM(BIA)) in 41 patients with cirrhosis (n = 20 with ascites; n = 21 without ascites) using total body potassium counting (BCM(TBP)) as a reference method. Arm muscle area and creatinine-derived lean body mass were compared with total body potassium data. In patients total body potassium was 24.4% lower than in controls and this loss was more severe in patients with ascites (-34.1%; P<.01). BCM(BIA) and BCM(TBP) were closely correlated in controls (r(2) =.87, P<.0001), patients without ascites (r(2) =.94, P <.0001) and patients with ascites (r(2) =.56, P<.0001). Removal of 6.2 +/- 3 L of ascites had only minor effects on BCM(BIA) (deviation of -0.18 kg/L ascites). Limits of agreement between both methods were wider in patients with ascites than in patients without (6.2 vs. 4.2 kg). In patients without ascites arm muscle area (r(2) =.64; P<.001) and lean body mass (r(2) =.55; P<.001) correlated significantly with total body potassium, but not in patients with ascites. For assessment of protein malnutrition in patients with cirrhosis, body cell mass determination by use of BIA offers a considerable advantage over other widely available but less accurate methods like anthropometry or the creatinine approach. Despite some limitations in patients with ascites, BIA is a reliable bedside tool for the determination of body cell mass in cirrhotic patients with and without ascites.

Neurovirulence of glycoprotein C(gC)-deleted bovine herpesvirus type-5 (BHV-5) and BHV-5 expressing BHV-1 gC in a rabbit seizure model

Herpesvirus glycoprotein C (gC) is one of the major virus attachment proteins. Bovine herpesvirus type 1 (BHV-1) causes respiratory and genital diseases in cattle, whereas BHV-5 causes acute meningoencephalitis in calves. The gC gene sequence of these two viruses are substantially different. To determine the contribution of the BHV-5 glycoprotein gC (gC5) to the neuropathogenesis of BHV-5, we have constructed two BHV-5 recombinants: gC-deleted BHV-5 (BHV-5gCDelta) and BHV-5 expressing BHV1 gC (BHV-5gC1). Neurovirulence properties of these viruses were analyzed using a rabbit seizure model that distinguishes BHV-1 and -5 based on their differential neuropathogeneses. Intranasal inoculations of BHV-5gCDelta and BHV-5gC1 viruses produced neurological signs in 30% and 40% of the infected rabbits, respectively. Immuno-histochemistry results showed that the number of infected neurons was 2 - 4-fold less with the gC-deleted BHV-5 than with the wild-type BHV-5. The gC-deleted BHV-5 did not invade the hippocampus but invaded additional sites not invaded by wild-type BHV-5. Similarly, the BHV-5gC1 virus failed to invade the hippocampus, but it did not invade the additional sites. Virus isolation results suggest that these recombinants replicate less efficiently in the brain than the wild-type and gC-revertant viruses. However, compared to the gC-deleted BHV-5, the gC-exchanged BHV-5gC1 replicated better within the CNS. These results indicate that gC regulates BHV-5 neurotropism in some areas of the olfactory pathway. Additionally, gC is important for BHV-5 neurovirulence in the olfactory pathway but it is not essential.

Effects of midbrain and spinal cord transections on sympathetic nerve responses to heating

In the present study, we investigated the contributions of forebrain, brain stem, and spinal neural circuits to heating-induced sympathetic nerve discharge (SND) responses in chloralose-anesthetized rats. Frequency characteristics of renal and splenic SND bursts and the level of activity in these nerves were determined in midbrain-transected (superior colliculus), spinal cord-transected [first cervical vertebra (C1)], and sham-transected (midbrain and spinal cord) rats during progressive increases in colonic temperature (T(c)) from 38 to 41.6-41.7 degrees C. The following observations were made. 1) Significant increases in renal and splenic SND were observed during hyperthermia in midbrain-transected, sham midbrain-transected, C1-transected, and sham C1-transected rats. 2) Heating changed the discharge pattern of renal and splenic SND bursts and was associated with prominent coupling between renal-splenic discharge bursts in midbrain-transected, sham midbrain-transected, and sham C1-transected rats. 3) The pattern of renal and splenic SND bursts remained unchanged from posttransection recovery levels during heating in C1-transected rats. We conclude that an intact forebrain is not required for the full expression of SND responses to increased T(c) and that spinal neural systems, in the absence of supraspinal circuits, are unable to markedly alter the frequency characteristics of SND in response to acute heat stress.

Activation of renal afferent pathways following furosemide treatment. I. Effects Of survival time and renal denervation

Three experiments were performed to determine whether renal afferent pathways were activated by the diuretic drug, furosemide. It was hypothesized that activated neurons of the renal afferent pathway would express the protein product Fos of the c-fos immediate early gene and be identified by immunocytochemical staining for Fos in the cell nucleus. In the first two experiments, rats were injected with either furosemide (5 mg) or vehicle solution (sterile isotonic saline) and sacrificed either 1.75 h (short-survival experiment) or 3.5 h (long-survival experiment) after injection. In both experiments, the furosemide-treated rats had significantly more Fos-positive cell nuclei than vehicle-treated rats in the subfornical organ (SFO), organum vasculosum lamina terminalis (OVLT), supraoptic nuclei (SON), and magnocellular region of the paraventricular nuclei (PVN) - areas previously shown to be activated by hypovolemia or peripheral angiotensin. In the short-survival experiment, the furosemide-treated rats had more Fos-positive cell nuclei in the nucleus of the solitary tract (NTS) and in the dorsal horn of the spinal cord at spinal levels T(11), T(12), and T(13). In contrast, furosemide treatment did not produce more Fos-positive cell nuclei in the NTS and dorsal horn of the spinal cord in the long-survival experiment. These results suggest that the activation of the SFO, OVLT, SON and PVN may be via a different mechanism than that of NTS or spinal cord dorsal horn. Based upon our previous work, we hypothesized that the NTS and spinal cord dorsal horn labeling was due to activation of sympathetic afferents originating in the kidney and labeling in forebrain structures was due to stimulation by angiotensin generated by renal renin release. To test this hypothesis, a third experiment was devised that was identical to the short-survival experiment, except that all rats had bilateral renal denervation surgery 1 week previously. In this experiment, furosemide administration increased the number of Fos-positive cells in the SFO, OVLT, SON and PVN, but not in the caudal thoracic spinal cord or NTS. These results together with the results of first two experiments lend support to our hypothesis that furosemide-induced neuronal activation in the thoracic spinal cord and NTS is due to activation of second- and/or third-order neurons of a renal sympathetic afferent pathway. Furosemide-induced activation in the SFO, OVLT, SON and PVN does not depend on renal innervation. It is hypothesized that activation in these forebrain regions depends on the action of angiotensin II that is generated after furosemide treatment. Our results indicate that both a hormonal pathway and a renal sympathetic afferent pathway conduct information from the kidney to the central nervous system (CNS) after furosemide treatment.

Activation of renal afferent pathways following furosemide treatment. II. Effect Of angiotensin blockade

The goal here and in the accompanying paper was to evaluate the two pathways used by the kidney to provide information to the central nervous system (CNS); e.g., the indirect, hormonal route via activation of the renin-angiotensin system and the direct pathway via activation of sympathetic afferents in the caudal thoracic spinal cord. Here, three experiments were designed to evaluate the actions of angiotensin elicited by subcutaneous injection of furosemide on neural activation of the CNS. The number of neurons immunocytochemically staining for the protein product (Fos) of the c-fos gene was used as an index of neuronal activation. In the first experiment, furosemide injection was preceded by treatment with a dose of Captopril, CAP, (an angiotensin-converting enzyme (ACE) inhibitor) that blocks the peripheral but not the central formation of angiotensin II. In the second experiment, furosemide injection was preceded by treatment with a higher dose of CAP; this dosage blocks the peripheral and central formation of angiotensin II. In the third experiment, furosemide injection was preceded by treatment with Losartan, a competitive receptor antagonist of type I angiotensin II receptors at a dose that would block central and peripheral angiotensin receptors. Control animals in each experiment received injections of vehicle (sterile isotonic saline) instead of furosemide. In each experiment, rats were sacrificed 1.75 h following furosemide or saline injection by transcardial perfusion and tissues were immunocytochemically processed for demonstration of Fos antigen. Rats receiving furosemide plus the low CAP dose showed more Fos-positive cells than control rats in the subfornical organ (SFO), organum vasculosum lamina terminalis (OVLT), supraoptic nucleus (SON), magnocellular region of the paraventricular nucleus, nucleus of the solitary tract (NTS), and caudal thoracic/rostral lumbar spinal cord dorsal horn. Rats receiving furosemide plus Losartan or furosemide plus the higher CAP dose did not show increased Fos immunoreactivity in any of the abovementioned structures relative to their respective control animals. We conclude that the receptor-mediated action of angiotensin II is in some way involved in the activation of the pathway that occurs in the SFO, OVLT, SON, and magnocellular region of the paraventricular nucleus (PVN) in response to furosemide treatment. It is possible that the furosemide-induced activation in the SON and PVN is not due to direct actions of angiotensin II on angiotensin receptors in those structures, but instead occurs synaptically as a result of inputs from the SFO and OVLT, which have themselves been activated directly by angiotensin II. In the accompanying paper, furosemide-induced activation in the NTS and caudal thoracic spinal cord is abolished by prior bilateral renal denervation, meaning that these neurons are likely part of a renal afferent pathway. Here, these structures did not elaborate Fos in animals injected with furosemide plus the high CAP dose or furosemide plus Losartan. Thus, the present results also suggest that the central blockade of the formation of angiotensin II or blockade of the actions of angiotensin II prevents in some way the activation of the renal afferent pathway mediated by the renal nerves (the direct pathway) in response to the actions of furosemide. Therefore, these results suggest that central angiotensin II is somehow involved in "priming" or increasing the sensitivity of the direct renal afferent pathway. Taken together with the accompanying paper, our results indicate that interruption of the direct pathway via renal denervation did not interfere with the elaboration of Fos in the lamina terminalis; in contrast, modification of the humoral renal afferent pathway can affect the sensitivity of the direct pathway. These results may have important implications for pathophysiological changes associated with fluid balance disorders including renal hypertension.

Bovine herpesvirus 5 glycoprotein E is important for neuroinvasiveness and neurovirulence in the olfactory pathway of the rabbit

Glycoprotein E (gE) is important for full virulence potential of the alphaherpesviruses in both natural and laboratory hosts. The gE sequence of the neurovirulent bovine herpesvirus 5 (BHV-5) was determined and compared with that of the nonneurovirulent BHV-1. Alignment of the predicted amino acid sequences of BHV-1 and BHV-5 gE open reading frames showed that they had 72% identity and 77% similarity. To determine the role of gE in the differential neuropathogenesis of BHV-1 and BHV-5, we have constructed BHV-1 and BHV-5 recombinants: gE-deleted BHV-5 (BHV-5gEDelta), BHV-5 expressing BHV-1 gE (BHV-5gE1), and BHV-1 expressing BHV-5 gE (BHV-1gE5). Neurovirulence properties of these recombinant viruses were analyzed using a rabbit seizure model (S. I. Chowdhury et al., J. Comp. Pathol. 117:295-310, 1997) that distinguished wild-type BHV-1 and -5 based on their differential neuropathogenesis. Intranasal inoculation of BHV-5 gEDelta and BHV-5gE1 produced significantly reduced neurological signs that affected only 10% of the infected rabbits. The recombinant BHV-1gE5 did not invade the central nervous system (CNS). Virus isolation and immunohistochemistry data suggest that these recombinants replicate and spread significantly less efficiently in the brain than BHV-5 gE revertant or wild-type BHV-5, which produced severe neurological signs in 70 to 80% rabbits. Taken together, the results of neurological signs, brain lesions, virus isolation, and immunohistochemistry indicate that BHV-5 gE is important for efficient neural spread and neurovirulence within the CNS and could not be replaced by BHV-1 gE. However, BHV-5 gE is not required for initial viral entry into olfactory pathway.

Characterization of the central cell groups regulating the kidney in the rat

Retrograde, transneuronal viral tracing technique combined with neurotransmitter immunohistochemistry was used to identify the type of neurons in spinal cord and brain that project to the rat's kidney. Pseudorabies virus (PRV) injections were made into the left kidney. After an incubation of 4 days postinjection, PRV-infected neurons were located immunocytochemically in the ipsilateral intermediolateral (IML) cell column of the spinal cord and several brainstem cell groups: medullary raphe nuclei, ventromedial medulla (VMM), rostral ventrolateral medulla (RVLM), A5 cell group and the hypothalamic paraventricular nucleus (PVH). In the medulla, serotonin (5-HT)-immunoreactive neurons of the caudal raphe nuclei, substance P (SP)-immunoreactive neurons of the raphe obscurus (ROb) nuclei and tyrosine hydroxylase (TH)-immunoreactive neurons of A5 cells were infected. In the VMM and RVLM, immunoreactive phenylethanolamine-N-methyltransferase (PNMT) neurons were infected. Some PRV-infected neurons in VMM contain 5-HT immunoreactivity. In the hypothalamus, immunoreactive vasopressin (VP) and oxytocin (OT) neurons were infected with PRV. This work indicates that sympathetic outflow to kidney is regulated by different types of neurons and the bulbospinal pathways regulating sympathetic outflow to the kidney are not obviously different from those regulating the other visceral, e.g., adrenal, heart, etc.

Spread of bovine herpesvirus type 5 (BHV-5) in the rabbit brain after intranasal inoculation

Following intranasal inoculation of wild-type BHV-5 in rabbits, we studied the sequential transneuronal passage of the virus in the CNS by immunocytochemistry, histopathology, and virus isolation. At 4 and 6 days postinfection (d.p.i.), rabbits had no or mild neurological signs, and virus was isolated only from the olfactory bulbs. At 8 and 9 d.p.i., infected rabbits had severe neurological signs, and virus could be isolated from multiple regions of the brain segments. In these rabbits, high titers of virus were consistently present in the anterior and posterior cortices, including frontal, piriform/entorhinal, temporal, parietal, and occipital cortices, the hippocampus and the amygdala. Virus was isolated occasionally from the midbrain/diencephalon and pons/medulla. Virus was not isolated from the cerebellum and trigeminal ganglion of rabbits examined from 2-12 d.p.i. Immunocytochemistry revealed virus-specific antigens at 4 d.p.i. within the glomerular layer, external plexiform layer, and mitral cell layer of the main olfactory bulb. At 6 d.p.i., virus-specific antigens were also present within the inner granular layer of the main olfactory bulb. At 8 and 9 d.p.i., widespread BHV-5-specific staining occurred in the areas of the brain connected to the main olfactory bulb, including the frontal/cingulate cortex, anterior olfactory nucleus, lateral olfactory tubercle, piriform/entorhinal cortex, hippocampus, amygdala, dorsal raphe, and locus coeruleus. In the trigeminal ganglion, specific staining was detected within a few neurons at 2,4, 6, 8 d.p.i. However, further spread of the virus along the trigeminal pathway was not evident. These data indicate that BHV-5 replicates and spreads preferentially in the olfactory pathway following intranasal instillation and that this viral spread correlated with the severity of neurological symptoms and histopathological lesions.

The renal afferent pathways in the rat: a pseudorabies virus study

Retrograde tract tracing studies have indicated that dorsal root ganglion cells from T8 to L2 innervate the rat's left kidney. Electrophysiology studies have indicated that putative second-order sympathetic afferents are found in the dorsal horn at spinal segments T10 to L1 in laminae V-VII. Here, the spread of pseudorabies virus through renal sensory pathways was examined following 2-5 days post-infection (PI) and the virus was located immunocytochemically using a rabbit polyclonal antibody. Two days PI, dorsal root ganglion neurons (first-order sympathetic afferents) were infected with PRV. An average of 1.2, 0.8, 2.1 and 4.4% of the infected dorsal root ganglion neurons were contralateral to the injected kidney at spinal segments T10, T11, T12 and T13, respectively. Four days PI, infected neurons were detected within laminae I and II of the dorsal horn of the caudal thoracic and upper lumbar spinal cord segments. The labeling patterns in the spinal cord are consistent with previous work indicating the location of renal sympathetic sensory pathways. The nodose ganglia were labeled starting 4 days PI, suggesting the involvement of parasympathetic sensory pathways. Five days PI, infected neurons were found in the nucleus tractus solitarius. In the present study, it was unclear whether the infected neurons in the nucleus tractus solitarius are part of sympathetic or parasympathetic afferent pathways or represent a convergence of sensory information. Renal denervation prevented the spread of the virus into the dorsal root ganglia and spinal cord. Sectioning the dorsal roots from T10-L3 blocked viral spread into the spinal cord dorsal horn, but did not prevent infection of neurons in dorsal root ganglion nor did it prevent infection of putative preganglionic neurons in the intermediolateral cell column. The present results indicated that renal afferent pathways can be identified after pseudorabies virus infection of the kidney. Our results suggest that renal afferents travel in sympathetic and parasympathetic nerves and that this information may converge at the NTS.

Neuropathology of bovine herpesvirus type 5 (BHV-5) meningo-encephalitis in a rabbit seizure model

The suitability of a rabbit seizure model for studying the neuropathogenesis of bovine herpesvirus type 5 (BHV-5) encephalitis was evaluated. Intranasal administration of BHV-5 (strain TX89) together with intramuscular administration of dexamethasone produced seizures in 70% of rabbits tested and meningo-encephalitis in 100%. Infectious BHV-5 was consistently isolated from the following sites: olfactory bulb; anterior cortex, containing the frontal cortex, olfactory tract and anterior portion of the olfactory cortex; posterior cortex, containing the temporal, parietal, piriform, entorhinal and occipital cortices; amygdala; hippocampus. Less frequently, BHV-5 was isolated from the midbrain and diencephalon, the pons and medulla, the cerebellum, and the trigeminal ganglia. Rabbits similarly infected with the Cooper strain of bovine herpesvirus type 1 showed no neurological signs or meningo-encephalitis, and virus was not recovered from the brain. The brains of BHV-5-infected rabbits showed neuronal degeneration, leptomeningitis, gliosis and perivascular cuffing, predominantly in the olfactory cortex (piriform and entorhinal cortices), amygdala and hippocampus. Mild lymphocytic meningitis was seen in the olfactory bulb and focal lymphocytic infiltration was sometimes present in the medulla and cerebellum. BHV-5, specific antigens and nucleic acids were detected in the olfactory cortex, amygdala and hippocampus by immunohistochemical methods and in-situ hybridization. The results suggested that, after intranasal BHV-5 inoculation, the virus spread to the central nervous system via the olfactory and trigeminal pathways. The olfactory pathway was more susceptible than the trigeminal pathway to neuropathogenic effects.

Effect of the estrous cycle on olfactory bulb response to vaginocervical stimulation in the rat: results from electrophysiology and Fos immunocytochemistry experiments

To determine whether the stage of the estrous cycle modified the response of olfactory bulb neurons to vaginocervical stimulation, (1) vaginocervical stimulation was applied to animals in proestrus-estrus and metestrus-diestrus and the extracellular electrophysiological response of units in the mitral cell layer of the main olfactory bulb was compared, and (2) the effect of vaginocervical or sham stimulation and the effect of the estrous cycle on the number of neurons stained immunocytochemically for Fos in the main and accessory olfactory bulb was examined. Animals in proestrus-estrus had basal firing rates of 21.8 +/- 1.8 spikes per 5 s and vaginocervical stimulation produced an increase in firing rate. In contrast, animals in metestrus-diestrus had a slower basal firing rate (14.3 +/- 2.3 spikes per 5 s) and vaginocervical stimulation produced a decrease in the firing rate. For animals in proestrus-estrus, vaginocervical stimulation increased the number of Fos-stained cells in the granular cell layer of the accessory olfactory bulb, and in the glomerular and in external plexiform layers of the main olfactory bulb. In contrast, the number of Fos-stained cells decreased in the granular cell layer of the main olfactory bulb after stimulation was applied to animals in proestrus-estrus. The number of Fos-stained cells in the granular layer of the accessory olfactory bulb and the granular and glomerular cell layers of the main olfactory bulb was modulated by the estrous cycle. Therefore, olfactory bulb activity, measured both electrophysiologically and by Fos staining, was affected by the estrous cycle and vaginocervical stimulation, and the two variables interacted. It is likely that integration of interoceptive and environmental stimulation is important for the normal expression of sexual behavior in the female rat.

Increased renal interstitial hydrostatic pressure causes c-fos expression in the rat's spinal cord dorsal horn

To describe a sympathetic afferent circuit, interstitial hydrostatic pressure in the left kidney was increased in anesthetized rats for 1.5 h to activate renal mechanoreceptor afferents. Following renal afferent stimulation, the number of immunocytochemically stained cells for the immediate early gene c-fos was increased within the dorsal horn of the spinal cord. Relative to the surgical control procedure, increasing renal interstitial hydrostatic pressure produced more immunocytochemically stained cells per tissue section in laminae I and II of the dorsal horn both ipsilateral and contralateral to the stimulated kidney in the three most caudal thoracic spinal segments. Further, the number of c-fos immunocytochemically stained cells per section in the dorsal horn ipsilateral to the stimulated kidney was 28% greater than the number of stained cells contralateral to it. The staining patterns in the dorsal horns of stimulated and control animals were similar with most labeled cells in laminae I and II. These results indicate that (1) c-fos immunocytochemical staining may be useful for tracing specific sympathetic afferent pathways, (2) sensory pathways affected by increased renal interstitial hydrostatic pressure include spinal neurons located at lower thoracic levels, and (3) some of this sympathetic afferent pathway is located contralateral to the stimulated kidney. Neurons in the contralateral dorsal horn activated by renal stimulation may mediate renorenal reflexes.

Ureteral ligation induces Fos expression in the dorsal horn

To describe a sympathetic afferent circuit, the left ureter was ligated in anesthetized rats for 1.5-2 h followed by immunocytochemical processing to localize expression of either the immediate early gene (IEG) c-fos or Krox-24 in the spinal cord or dorsal root ganglia (DRG). No IEG expression was detected in DRG. Both Fos and Krox-24 expression was found in the dorsal horn. More Fos immunocytochemically stained cells were found in the dorsal horn both ipsi- and and contralateral to the ligated ureter at spinal segments T10-T13 after ureteral than after either sham ligation or anesthesia control procedures. More Fos stained cells were in the dorsal horn ipsilateral to the ligated ureter than on the contralateral side. The Fos staining patterns in the dorsal horn of ligated and sham-ligated animals were similar with most labeled cells in dorsomedial portions of laminae I and II. In contrast, the Fos staining pattern in the dorsal horn in anesthetized animals (unoperated controls) was noticeably different from operated animals with the most Fos cells in the ventrolateral part of laminae I-II. These results indicate that (1) Fos Immunocytochemistry may be useful for tracing sympathetic afferent pathways, (2) the sensory pathway activated by ureteral ligation enters the spinal cord at lower thoracic levels, where renal and upper ureteral afferents are terminating, and (3) some of this sympathetic afferent pathway is located contralateral to the stimulated kidney. Neurons activated by ureteral ligation in the contralateral dorsal horn may mediate reno-renal reflexes.

Nonuniform sympathetic nerve responses to intravenous hypertonic saline infusion

Peripheral hyperosmolality produced by the intravenous infusion of hypertonic saline (HTS) increases mean arterial blood pressure (MAP) in experimental animals. The mechanisms mediating the pressor response have not been fully ascertained, but likely involve vasopressin and/or activation of the sympathetic nervous system. The primary aim of this study was to determine if HTS infusion produces regionally uniform or nonuniform changes in sympathetic nerve discharge (SND). For this purpose we recorded renal, splanchnic and lumbar SND during intravenous HTS infusion (2.5 M NaCl, 10 microliters/100 g BW per min) in chloralose-anesthetized, Sprague-Dawley rats. In rats with intact arterial baroreceptors, HTS infusion significantly increased MAP (17 +/- 2 mmHg) and lumbar SND (29 +/- 13%) but reduced splanchnic (-52 +/- 7%) and renal SND (-33 +/- 8%). After sinoaortic denervation (SAD), HTS infusion significantly increased MAP (28 +/- 6 mmHg) and lumbar SND (27 +/- 9%) and decreased renal SND (-22 +/- 8%). The increase in lumbar SND occurred significantly sooner in SAD compared with baroreceptor-intact rats. In contrast, splanchnic SND remained unchanged from control levels during HTS infusion after SAD. These results demonstrate that HTS infusion produces regionally nonuniform changes in SND, and suggest that the pressor and lumbar sympathoexcitatory responses to HTS infusion are opposed by the arterial baroreceptors.

A constant current source for extracellular microiontophoresis

A sophisticated constant-current source suitable for extracellular microiontophoresis of tract-tracing substances, such as Phaseolus vulgaris leucoagglutinin, Biocytin or Fluoro-Gold, is described. This design uses a flyback switched-mode power supply to generate controllable high-voltage and operational amplifier circuitry to regulate current and provide instrumentation. Design features include a fast rise time, +/- 2000 V supply (stable output in < 250 ms), simultaneous load current and voltage monitoring, and separate pumping and holding current settings. Three features of this constant-current source make it especially useful for extracellular microiontophoresis. First, the output voltage monitor permits one to follow changes in the microelectrode resistance during current injection. Second, the voltage-limit (or out-of-compliance) indicator circuitry will sound an alarm when the iontophoretic pump is unable to generate the desired current, such as when the micropipette is blocked. Third, the high-compliance voltage power supply insures up to +/- 20 microA of current through 100 M omega resistance. This device has proven itself to be a reliable constant-current source for extracellular microiontophoresis in the laboratory.

Direct retinal communication with the peri-amygdaloid area

Retinal projections to the basal forebrain in male Syrian hamsters were examined at the ultrastructural level following bilateral intraocular injections of horseradish peroxidase conjugated to either cholera toxin (CT-HRP) or wheat germ agglutinin (WGA-HRP). Light level microscopic analysis confirmed retinal projections along basal telencephalon, and examination on the electron microscope of individual fibers from the peri-amygdaloid area revealed en passant synaptic profiles. Sections from animals treated with WGA-HRP showed evidence of transsynaptic communication in the form of labeled dendrites in the peri-amygdaloid area. Taken together, these data show that the retina communicates directly with the periamygdaloid area, where photic and chemosensory information may be integrated to modulate reproductive behavior.

Effects of continuous environmental illumination on the albino rat hypothalamo-neurohypophysial system

Continuous environmental illumination or constant light (LL) exposure causes a suppression of daily water intake, and long-term exposure of greater than 19 days produces a hypertrophy of magnocellular neuroendocrine cells (MNCs) in the hypothalamus. These findings led Glantz to hypothesize that LL increases the secretion of vasopressin (VP). We wanted to determine whether LL could trigger morphological changes within the hypothalamo-neurohypophysial system (HNS) seen with other manipulations that result in enhanced hormone release. The posterior pituitary of male albino rats that were exposed to LL for 24 or 48 h were examined ultrastructurally for evidence of enhanced hormone release. In addition, water intake, plasma VP levels, and MNC size within the supraoptic nucleus (SON) were measured. After LL exposure, the posterior pituitary morphology was different, suggesting enhanced hormone release. LL exposure did not affect plasma VP or the size of SON MNCs, but did suppress drinking behavior. These data show that posterior pituitary morphology is affected rapidly by LL exposure. The HNS response to LL exposure may consist of changes within the first 24 h of LL found within the posterior pituitary followed later by hypertrophy of the SON MNCs.

Supraoptic nucleus afferents from the accessory olfactory bulb: evidence from anterograde and retrograde tract tracing in the rat

Our earlier electrophysiological work provided evidence of a direct input to the supraoptic nucleus (SON) from the olfactory bulbs; however, these experiments could not determine if the input originated in the main and/or accessory portions of the olfactory bulb. Here, a connection between the accessory olfactory bulb (AOB) and the SON of the rat was examined using a combination of anatomic techniques. We employed neurophysin immunocytochemistry to delineate the morphological boundaries of the SON and the proximal arborizations of supraoptic dendrites. Accessory olfactory bulb efferents to the SON were studied by injection of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the AOB. The distribution of retrogradely labeled cells within the AOB was also determined after injection of either rhodamine-labeled latex microspheres (rhodamine beads) or Fluoro-Gold (FG) into the SON. Neurophysin immunocytochemistry revealed that SON dendrites extended beyond the generally accepted boundaries of the nucleus, coursing ventrolaterally along the surface of the periamygdaloid cortex. Anterograde tract tracing with WGA-HRP labeled AOB efferents including a dense plexus of terminals and fibers around the ipsilateral SON along the path of the ventrally projecting dendrites. Injections of retrograde tracers into the SON resulted in rhodamine bead or FG labeling of mitral cells throughout the ipsilateral AOB. Taken together, these anatomic studies suggest a direct projection from the accessory olfactory bulb to the SON of the rat and thus a vomeronasal organ to SON pathway.

Intravenous injection of Evans Blue labels magnocellular neuroendocrine cells of the rat supraoptic nucleus in situ and after dissociation

Previous work has demonstrated that intravenous injection of neuronal tracers, e.g. horseradish peroxidase or Fast Blue, can retrogradely label neurons in brain areas that project outside the blood-brain barrier, e.g. magnocellular neuroendocrine neurons of the hypothalamus. Here we have shown that 24 h after intravenous injection of the fluorescent retrograde tracer Evans Blue, the same population of magnocellular neuroendocrine neurons is labeled in the paraventricular, supraoptic and accessory magnocellular nuclei. Parvicellular neuroendocrine cells in the paraventricular nuclei are also labeled. Most Evans Blue-labeled magnocellular neuroendocrine cells in the supraoptic nucleus could be stained immunocytochemically for neurophysins, suggesting that these neurons continue to produce their peptide hormones after taking up the fluorescent dye. Ultrastructural observation of supraoptic cells retrogradely labeled with Evans Blue shows that 95% of the neurons appeared healthy. There was no ultrastructural evidence of degeneration, hyperstimulation, or interruption of the axoplasmic flow. Labeling the neuroendocrine cells with Evans Blue did not alter the size of magnocellular cells, the animal's fluid balance or ingestive behavior. Following enzymatic/mechanical dissociation of the supraoptic nucleus from animals that had been injected with Evans Blue 24 h previously, phase-bright neurons that often contained fluorescent material were observed, thus identifying these neurons as neuroendocrine. Recording from identified neuroendocrine cells showed that these neurons generated spontaneous or current-evoked overshooting action potentials with an afterhyperpolarization and had negative resting membrane potentials. Action potential broadening, a feature of magnocellular neurons, was observed during bursts of action potentials elicited by depolarizing current injection. Taken together, this work would suggest that Evans Blue is non-toxic at the doses used and that it provides a method to identify single neuroendocrine cells in primary cell cultures made from adult hypothalamus for voltage-clamp recordings.

Retinohypothalamic tract in the female albino rat: a study using horseradish peroxidase conjugated to cholera toxin

There are several anatomically and functionally distinct retinofugal pathways, one of which is the retinohypothalamic tract (RHT). In this study, horseradish peroxidase conjugated to cholera toxin (CT-HRP), a sensitive neural tracer, was employed to describe the RHT in the female albino rat. Following uniocular injection of CT-HRP, both medial and lateral components of the RHT were evident. The medial component swept caudally into and through the suprachiasmatic nucleus (SCN) and dorsally to the subparaventricular zone. Terminal label was seen in the medial preoptic region, peri-SCN area, retrochiasmatic area, periventricular nucleus, anterior and central parts of the anterior hypothalamic area, and the subparaventricular zone. In contrast to the more focused and symmetrical medial component, the lateral component was diffuse with light terminal label in the lateral preoptic region, olfactory tubercle, lateral hypothalamus, supraoptic nucleus, and medial and posteroventral medial amygdaloid nuclei. The striking exception to this diffuse pattern of the lateral component was an extremely dense columnar terminal field over the dorsal border of the supraoptic nucleus. Whereas the intensity of label in terminal fields of the medial component was often similar on the sides ipsilateral and contralateral to the injection, the lateral component was consistently asymmetrical with greater labeling on the side contralateral to the injection. In addition, a light projection arrived at several thalamic nuclei by returning toward the thalamus from the tectal or pretectal areas via stria medullaris, and thus was not a part of the RHT. Implications for circadian as well as noncircadian photobiologic effects are discussed.

Retinofugal projections to the hypothalamus, anterior thalamus and basal forebrain in hamsters

In Part a of the study, the retinal inputs to the hypothalamus, anterior thalamus and basal forebrain of Syrian hamsters were studied using intraocular injections of horseradish peroxidase conjugated to cholera toxin (CT-HRP). In the hypothalamus, the heaviest retinal input was to the suprachiasmatic nucleus (SCN), however, many labeled fibers coursed through the SCN to reach more caudal, periventricular and lateral sites including the anterior and lateral hypothalamus, the paraventricular nucleus (PVN), the subparaventricular zone, the ventromedial nucleus and the pars compacta of the dorsomedial nucleus. Some of these fibers continued dorsally into the zona incerta (ZI). Other fibers emerged from the lateral optic chiasm and traveled either rostro-medially to end in the preoptic area (POA) or further laterally to reach the supraoptic nucleus. A subset of fibers extended laterally from the chiasm to form a well-defined tract which provided input to the pyriform cortex. The extrageniculate retinal input to the thalamus was to the anterior thalamic area (AT) via the stria terminalis. In Part b, injections of rhodamine-labeled latex microspheres were made in three brain areas that contained labeled fibers after intraocular injections of CT-HRP. Injections in the AT, PVN/ZI area and POA consistently produced a small number of labeled retinal ganglion cells, whereas control injections did not. Taken together, these results indicate that many regions of the brain involved in the control of reproductive and regulatory functions receive photic informations via direct retinal inputs. These retinal inputs may play a role in the photoperiodic modulation of physiology and behavior.

Collateral input to the paraventricular and supraoptic nuclei in rat. II. Afferents from the ventral lateral medulla and nucleus tractus solitarius

In the rat, medullary afferents to the hypothalamic magnocellular nuclei mediate the baroreceptor reflexes of vasopressinergic neurons and the cholecystokinin- or gastric distention-induced excitation of oxytocinergic neurons. One strategy that reflexes such as these may use to coordinate the activity of magnocellular neuroendocrine neurons is collateral branching of input. Previous work has shown that the distributions of medullary neurons projecting to the paraventricular and the supraoptic nuclei overlap and that their axons branch. Thus, we hypothesized that single neurons in the ventral lateral medulla and/or the nucleus tractus solitarius would project to both the paraventricular and supraoptic nuclei via collateral branches of their axons. Medullary afferent neurons were retrogradely labeled after injection into the paraventricular and the supraoptic nucleus on one side of the brain with two different fluorescent tracers: Fluoro-Gold or rhodamine-labeled latex microspheres. The topographic distribution of labeled cells in the medulla containing either a single fluorescent tracer or both tracers were plotted. Of these labeled neurons, a small percentage (7%) contained both dyes, suggesting that they send collateral branches to both of the magnocellular neuroendocrine nuclei injected. Single labeled cells were both ipsi- and contralateral to the injected side (53% ipsilateral), but most double-labeled cells were ipsilateral (84%). In rats, areas that project to both the paraventricular and the supraoptic nuclei may act upon both nuclei together. Thus, afferent inputs, in conjunction with the known inter- and intracellular changes that take place within the magnocellular nuclei, may be involved with the coordinated responses throughout magnocellular neuroendocrine system during medullary reflexes, i.e., the baroreceptor-mediated reflexes or the gastric distention reflexes.

Voltage-clamp recordings from identified dissociated neuroendocrine cells of the adult rat supraoptic nucleus

In vitro intracellular recordings of membrane potential obtained from the oxytocin and vasopressin neurons of the mammalian hypothalamo-neurohypophysial system in slices (1-3) and expiants (4, 5) have demonstrated many of the intrinsic properties of these magnocellular neuroendocrine cells (MNCs). Voltage-clamp techniques, which are required to study directly the currents underlying intrinsic or transmitter-evoked potential changes, have been applied to cultured embryonic (6) or neonatal supraoptic neurons (7-9) and have been successfully applied to adult supraoptic neurons in situ in only one laboratory (10, 11). We have modified a technique for dissociation of viable adult guineapig hippocampal neurons (12) to dissociate supraoptic MNCs from adult rats for voltage-clamp studies. MNCs were selectively labelled with a fluorescent dye in vivo so that they could be identified after dissociation and prior to making recordings. These data have been published in abstract form elsewhere (13, 14).

Collateral input to the paraventricular and supraoptic nuclei in rat. I. Afferents from the subfornical organ and the anteroventral third ventricle region

Injections of two fluorescent retrograde tracers were used to investigate the existence of collateral branching of input to the hypothalamic magnocellular neuroendocrine neurons. Injection of one tracer (either Fluoro-Gold or rhodamine-labeled microspheres) into the supraoptic nucleus and the other tracer into the ipsilateral paraventricular nucleus produced labeled neurons within the subfornical organ and the anteroventral third ventricle area. Some labeled cells were found to contain both fluorescent tracers (double-labeled cells), suggesting that they project to both the paraventricular and supraoptic nuclei via branching axons. Most double-labeled cells were found within the subfornical organ. Fewer of these cells were located within the nucleus medianus preopticus, and still fewer were distributed in the organum vasculosum lamina terminalis, the bed nucleus of the stria terminalis, and the medial and the lateral preoptic areas. These data present the first direct evidence that single cells may provide input to more than one magnocellular neuroendocrine nucleus. Hypothetically, hormonal release would require coordinated firing of many magnocellular cells. Thus, the branched input to these neurons may assist in the organization and the timely activation of this system in response to physiological stimuli.

Magnocellular tuberomammillary nucleus input to the supraoptic nucleus in the rat: anatomical and in vitro electrophysiological investigations

Anatomical and electrophysiological methods were used to investigate the existence and role of inputs from the magnocellular tuberomammillary nucleus to the supraoptic nucleus. After injecting either Fluoro-Gold or rhodamine-labeled latex microspheres into the supraoptic nucleus, consistent patterns of retrogradely labeled neurons within the tuberomammillary nucleus were observed. The results indicate that both subdivisions of the supraoptic nucleus, the tuberal and the anterior, receive input from the tuberomammillary nucleus. Injections into the tuberal supraoptic nucleus tended to label more cells in the contralateral tuberomammillary nucleus, while injections into the anterior supraoptic nucleus may label more cells on the ipsilateral side. The in vitro intracellular electrophysiological results support the anatomical findings and extend them in several ways. Some tuberomammillary neurons were found to project to the supraoptic nuclei on both sides of the brain. Intracellular Lucifer Yellow injections into tuberomammillary cells after electrophysiological recording revealed labeled axons that were traceable into the supraoptic nucleus, where apparent varicosities (possible en passant terminals) were seen. Magnocellular tuberomammillary nucleus neurons had characteristic passive and active membrane properties and morphology, similar to histaminergic neurons in this area studied by other workers. Finally, in two of the 21 cases, Lucifer Yellow injection into one neuron revealed dye-coupled pairs of tuberomammillary neurons. Previous work by others has shown that histamine excited cells in the tuberal subdivision of the supraoptic nucleus, stimulating vasopressin release, and that the tuberomammillary nucleus provides histaminergic input to the anterior portion of the supraoptic. The present findings show that the tuberomammillary nucleus supplies input to both subdivisions of the supraoptic nucleus and that this input is provided bilaterally. Taken together with previous work, these data suggest that the tuberomammillary nucleus provides histaminergic input to the supraoptic nucleus and may be involved specifically with vasopressin release.