Impact of the COVID-19 pandemic on the incidence of surgical site infection after orthopaedic surgery: an interrupted time series analysis of the nationwide surveillance database in Japan

BACKGROUND

During the COVID-19 pandemic, hygiene awareness was increased in communities and hospitals. However, there is controversy regarding whether such circumstances affected the incidence of surgical site infections (SSIs) in the orthopaedic surgical field.

AIM

To examine the impact of the COVID-19 pandemic on the incidence of SSIs after orthopaedic surgery.

METHODS

The medical records of patients having undergone orthopaedic surgery were extracted from the nationwide surveillance database in Japan. The primary outcomes were the monthly incidences of total SSIs, deep or organ/space SSIs, and SSIs due to meticillin-resistant Staphylococcus aureus (MRSA). Interrupted time series analysis was conducted between pre-pandemic (January 2017 to March 2020) and pandemic (April 2020 to June 2021) periods.

RESULTS

A total of 309,341 operations were included. Interrupted time series analysis adjusted for seasonality showed no significant changes in the incidence of total SSIs (rate ratio 0.94 and 95% confidence interval 0.98-1.02), deep or organ/space SSIs (0.91, 0.72-1.15), or SSIs due to MRSA (1.07, 0.68-1.68) along with no remarkable slope changes in any parameter (1.00, 0.98-1.02; 1.00, 0.97-1.02; and 0.98, 0.93-1.03, respectively).

CONCLUSIONS

Awareness and measures against the COVID-19 pandemic did not markedly influence the incidence of total SSIs, deep or organ/space SSIs, or SSIs due to MRSA following orthopaedic surgery in Japan.

Deficiency of sphingomyelin synthase 1 but not sphingomyelin synthase 2 reduces bone formation due to impaired osteoblast differentiation

Background

There are two isoforms of sphingomyelin synthase (SMS): SMS1 and SMS2. SMS1 is located in the Golgi apparatus only while SMS2 is located in both the plasma membrane and the Golgi apparatus. SMS1 and SMS2 act similarly to generate sphingomyelin (SM). We have undertaken the experiments reported here on SMS and osteoblast differentiation in order to better understand the role SMS plays in skeletal development.

Methods

We analyzed the phenotype of a conditional knockout mouse, which was generated by mating a Sp7 promoter-driven Cre-expressing mouse with an SMS1-floxed SMS2-deficient mouse (Sp7-Cre;SMS1^f/f;SMS2^−/− mouse).

Results

When we compared Sp7-Cre;SMS1^f/f;SMS2^−/− mice with C57BL/6, SMS2-deficient mice (SMS1^f/f;SMS2^−/−) and SP7-Cre positive control mice (Sp7-Cre, Sp7-Cre;SMS1^+/+;SMS2^+/− and Sp7-Cre;SMS1^+/+;SMS2^−/−), we found that although cartilage formation is normal, Sp7-Cre;SMS1^f/f;SMS2^−/− mice showed reduced trabecular and cortical bone mass, had lower bone mineral density, and had a slower mineral apposition rate than control mice. Next, we have used a tamoxifen-inducible knockout system in vitro to show that SMS1 plays an important role in osteoblast differentiation. We cultured osteoblasts derived from ERT2-Cre;SMS1^f/fSMS2^−/− mice. We observed impaired differentiation of these cells in response to Smad1/5/8 and p38 that were induced by bone morphogenic protein 2 (BMP2). However, Erk1/2 phosphorylation was unaffected by inactivation of SMS1.

Conclusions

These findings provide the first genetic evidence that SMS1 plays a role in bone development by regulating osteoblast development in cooperation with BMP2 signaling. Thus, SMS1 acts as an endogenous signaling component necessary for bone formation.

Polyhedral microcrystals encapsulating bone morphogenetic protein 2 improve healing in the alveolar ridge

Atelocollagen sponges incorporating polyhedra encapsulating bone morphogenetic protein 2 (BMP-2) were implanted into lateral bone defects in the mandible. Half of the bone defects on the left side were treated with atelocollagen sponges containing 1.8 × 10(7) BMP-2 polyhedra, and half were treated with sponges containing 3.6 × 10(6) BMP-2 polyhedra. As controls, we treated the right-side bone defects in each animal with an atelocollagen sponge containing 5 µg of recombinant human BMP-2 (rhBMP-2) or 1.8 × 10(7) empty polyhedral. After a healing period of six months, whole mandibles were removed for micro-computed tomography (CT) and histological analyses. Micro-CT images showed that more bone had formed at all experimental sites than at control sites. However, the density of the new bone was not significantly higher at sites with an atelocollagen sponge containing BMP-2 polyhedra than at sites with an atelocollagen sponge containing rhBMP-2 or empty polyhedra. Histological examination confirmed that the BMP-2 polyhedra almost entirely replaced the atelocollagen sponges and connected the original bone with the regenerated bone. These results show that the BMP-2 delivery system facilitates the regeneration of new bone in the mandibular alveolar bone ridge and has an advance in the technology of bone regeneration for implant site development.

3D co-cultures of keratinocytes and melanocytes and cytoprotective effects on keratinocytes against reactive oxygen species by insect virus-derived protein microcrystals

Stable protein microcrystals called polyhedra are produced by certain insect viruses. Cytokines, such as fibroblast growth factors (FGFs), can be immobilized within polyhedra. Here, we investigated three-dimensional (3D) co-cultures of keratinocytes and melanocytes on collagen gel containing FGF-2 and FGF-7 polyhedra. Melanocytes were observed to reside at the base of the 3D cell culture and melanin was also typically observed in the lower layer. The 3D cell culture model with FGF-2 and FGF-7 polyhedra was a useful in vitro model of the epidermis due to effective melanogenesis, proliferation and differentiation of keratinocytes. FGF-7 polyhedra showed a potent cytoprotective effect when keratinocytes were treated with menadione, which is a generator of reactive oxygen species. The cytoprotective effect was activated by the inositol triphosphate kinase-Akt pathway leading to upregulation of the antioxidant enzymes superoxide dismutase and peroxiredoxin 6.

Control of angiogenesis by VEGF and endostatin-encapsulated protein microcrystals and inhibition of tumor angiogenesis

Encapsulation of cytokines within protein microcrystals (polyhedra) is a promising approach for the stabilization and delivery of therapeutic proteins. Here, we investigate the influence of vascular endothelial growth factor (VEGF) microcrystals and endostatin microcrystals on angiogenesis. VEGF was successfully encapsulated into microcrystals derived from insect cypovirus with overexpression of protein disulfide bond isomerase. VEGF microcrystals were observed to increase the phosphorylation of p42/p44 MAP kinase and to stimulate the proliferation, migration, and network and tube formation of human umbilical vein endothelial cells (HUVECs). Endostatin was also successfully encapsulated into microcrystals. Endostatin microcrystals showed antiangiogenesis activities and inhibited the migration, and network and tube formation of HUVECs. Local administration of endostatin microcrystals in mice inhibited both angiogenesis and tumor growth with clear significant differences between treatment and control groups. Endostatin microcrystals only affected angiogenesis, but had no significant effect on lymphangiogenesis compared to controls. Local therapy using endostatin microcrystals offers a potential approach to achieve sustained therapeutic release of antiangiogenic molecules for cancer treatment.

Gelatin powders accelerate the resorption of calcium phosphate cement and improve healing in the alveolar ridge

The aim of this study was to show the effectiveness of combining calcium phosphate cement and gelatin powders to promote bone regeneration in the canine mandible. We mixed gelatin powders with calcium phosphate cement to create a macroporous composite. In four beagle dogs, two saddle-type bone defects were created on each side of the mandible, and calcium phosphate cement alone or calcium phosphate cement containing composite gelatin powders was implanted in each of the defects. After a healing period of six months, mandibles were removed for µCT and histological analyses. The µCT and histological analyses showed that at experimental sites at which calcium phosphate cement alone had been placed new bone had formed only around the periphery of the residual calcium phosphate cement and that there had been little or no ingrowth into the calcium phosphate cement. On the other hand, at experimental sites at which calcium phosphate cement containing composite gelatin powders had been placed, we observed regenerated new bone in the interior of the residual calcium phosphate cement as well as around its periphery. The amount of resorption of calcium phosphate cement and bone regeneration depended on the mixing ratio of gelatin powders to calcium phosphate cement. New bone replacement was significantly better in the sites treated with calcium phosphate cement containing composite gelatin powders than in those treated with calcium phosphate cement alone.

Evaluation of guided bone regeneration with poly(lactic acid-co-glycolic acid-co-ε-caprolactone) porous membrane in lateral bone defects of the canine mandible

PURPOSE

The aim of this study was to qualitatively evaluate a poly(lactic acid-co-glycolic acid-co-ε-caprolactone) (PLGC) membrane as a barrier for guided bone regeneration in the canine mandible and to compare it to a nonresorbable polytetrafluoroethylene (PTFE) membrane.

MATERIALS AND METHODS

Two wedge-shaped bone defects were created bilaterally in the mandibles of 12 beagle dogs. The bone defects in the left mandible were divided into three groups and treated as follows: PLGC membrane alone, PLGC membrane plus autogenous cortical bone chips, and titanium-reinforced expanded PTFE (TR-PTFE) membrane. The bone defects in the right mandible of each animal were left without membranes as a control. Computed tomography (CT) was performed at 3 and 6 months postoperative to evaluate bone regeneration. After a healing period of 6 months, the mandibles were removed en bloc for micro-CT and histologic analyses.

RESULTS

CT analyses at 3 and 6 months showed that there was significantly more bone augmentation at all experimental sites than at the control sites. The volume of bone at defect sites covered with TR-PTFE was significantly greater than at defect sites covered with PLGC membrane with or without autogenous cortical bone. Micro-CT measurements showed that the volume of new bone formed at sites covered with TR-PTFE was significantly greater than at sites covered with PLGC membrane. However, the density of new bone was significantly higher at sites covered with PLGC membrane, with or without cortical bone, than at sites covered with TR-PTFE. Histologic analysis verified the presence of well-vascularized loose connective tissue in the pores of the PLGC membrane.

CONCLUSIONS

Compared to TR-PTFE, the macroporous bioresorbable PLGC membrane did not significantly increase the amount of new bone in defect sites, but it facilitated the regeneration of mature bone.

Alveolar bone regeneration using poly-(lactic acid-co-glycolic acid-co-ε-caprolactone) porous membrane with collagen sponge containing basic fibroblast growth factor: An experimental study in the dog

The aim of this study was to evaluate the effects of combining porous poly-lactic acid-co-glycolic acid-co-ε-caprolactone (PLGC) as a barrier membrane and collagen sponge containing basic fibroblast growth factor (bFGF) to promote bone regeneration in the canine mandible. In six beagle dogs, two lateral bone defects per side were created in the mandible. The lateral bone defects on the left side were treated with a PLGC membrane plus a collagen sponge containing bFGF. In half of these, the collagen sponge contained 50 µg of bFGF. In the other half, it contained 250 µg of bFGF. As a control, we treated the right-side bone defects in each animal with the same PLGC membrane but with a collagen sponge containing phosphate buffered saline. Computed tomography (CT) images were recorded at 3 and 6 months post-op to evaluate regeneration of the bone defects. After a healing period of 6 months, whole mandibles were removed for micro-CT and histological analyses. The post-op CT images showed that more bone had formed at all experimental sites than at control sites. At 3 months post-op, the volume of bone at defect sites covered with PLGC membrane plus 250 µg of bFGF was significantly greater than it was at defect sites covered with PLGC membrane plus 50 µg of bFGF. At 6 months post-op, however, this difference was smaller and not statistically significant. Micro-CT measurement showed that the volume of new bone regenerated at bone-defect sites, covered with PLGC membrane plus bFGF, was significantly greater than that of control sites. However, the presence or absence of bFGF in the collagen sponge did not significantly affect the bone density of new bone. These results suggest that the macroporous bioresorbable PLGC membrane plus collagen sponge containing bFGF effectively facilitates healing in GBR procedures.

NK4 gene therapy combined with cisplatin inhibits tumour growth and metastasis of squamous cell carcinoma

BACKGROUND

NK4 inhibits vascularisation in tumour tissues, thereby arresting tumour growth. However, the antitumour efficacy of individual antiangiogenic molecules expressed in vivo is not sufficiently potent to induce regression in animal models. One of the strategies to overcome this disadvantage is to use chemotherapy.

MATERIALS AND METHODS

This study evaluated the efficacy of combining NK4 gene therapy with cisplatin to treat experimental squamous cell carcinomas. For gene therapy, biodegradable cationised gelatin microspheres were used for the controlled release of NK4 plasmid DNA.

RESULTS

A combined regimen of antiangiogenic gene therapy and low-dose cisplatin led to a marked decrease in tumour volume and vascularity, and caused increased apoptosis compared to NK4 gene therapy alone. Moreover, combination treatment of NK4 gene therapy and low-dose cisplatin dramatically inhibited the formation of lung metastases.

CONCLUSION

NK4 gene therapy combined with low-dose cisplatin may be an effective regimen for treating oral squamous cell carcinoma.

Enhanced regeneration of critical bone defects using a biodegradable gelatin sponge and beta-tricalcium phosphate with bone morphogenetic protein-2

We examine the osteogenicity of a sponge biomaterial consisting of a biodegradable mixture of gelatin and beta-tricalcium phosphate (betaTCP) that bound bone morphogenetic protein 2 (BMP-2) in critical-sized bone defects in rats. Gelatin-betaTCP sponges containing either phosphate buffered saline or incorporating BMP-2 are implanted into 5 mm diameter bone defects created in rat mandibles. We assess the defects biweekly for 8 weeks following implantation. There is significantly higher osteoinductive activity and significantly more Gla-osteocalcin content at bone-defect healing sites treated with gelatin-betaTCP sponges incorporating BMP-2 than there is in those treated with sponges that did not contain BMP-2. Histologically, new bone that contains bone marrow and that is connected to the original bone almost entirely replaces the regenerated bone. These results show that biodegradable gelatin-betaTCP incorporating BMP-2 is osteogenic enough to promote healing in large bone defects.

Cationized gelatin delivery of a plasmid DNA expressing small interference RNA for VEGF inhibits murine squamous cell carcinoma

Double-stranded RNA (dsRNA) plays a major role in RNA interference (RNAi), a process in which segments of dsRNA are initially cleaved by the Dicer into shorter segments (21-23 nt) called small interfering RNA (siRNA). These siRNA then specifically target homologous mRNA molecules causing them to be degraded by cellular ribonucleases. RNAi down regulates endogenous gene expression in mammalian cells. Vascular endothelial growth factor (VEGF) is a key molecule in vasculogenesis as well as in angiogenesis. Tumor growth is an angiogenesis-dependent process, and therapeutic strategies aimed at inhibiting angiogenesis are theoretically attractive. To investigate the feasibility of using siRNA for VEGF in the specific knockdown of VEGF mRNA, thereby inhibiting angiogenesis, we have performed experiments with a DNA vector based on a siRNA system that targets VEGF (siVEGF). It almost completely inhibited the expression of three different isoforms (VEGF120, VEGF164 and VEGF188) of VEGF mRNA and the secretion of VEGF protein in mouse squamous cell carcinoma NRS-1 cells. The siVEGF released from cationized gelatin microspheres suppressed tumor growth in vivo. A marked reduction in vascularity accompanied the inhibition of a siVEGF-transfected tumor. Fluorescent microscopic study showed that the complex of siVEGF with cationized gelatin microspheres was still present around the tumor 10 days after injection, while free siVEGF had vanished by that time. siVEGF gene therapy increased the fraction of vessels covered by pericytes and induced expression of angiopoietin-1 by pericytes. These data suggest that cationized-gelatin microspheres containing siVEGF can be used to normalize tumor vasculature and inhibit tumor growth in a NRS-1 squamous cell carcinoma xenograft model.

Essential role of LFA-1 in activating Th2-like responses by alpha-galactosylceramide-activated NKT cells

NKT cells produce large amounts of cytokines associated with both the Th1 (IFN-gamma) and Th2 (IL-4) responses following stimulation of their invariant Valpha14 Ag receptor. The role of adhesion molecules in the activation of NKT cells by the Valpha14 ligand alpha-galactosylceramide (alpha-GalCer) remains unclear. To address this issue, LFA-1-/- (CD11a-/-) mice were used to investigate IL-4 and IFN-gamma production by NKT cells following alpha-GalCer stimulation. Intriguingly, LFA-1-/- mice showed increased IL-4, IL-5, and IL-13 production and polarized Th2-type responses in response to alpha-GalCer in vitro and in vivo. Furthermore, the Th2-specific transcription factor GATA-3 was up-regulated in alpha-GalCer-activated NKT cells from LFA-1-/- mice. These results provide the first genetic evidence that the adhesion receptor LFA-1 has a crucial role in Th2-polarizing functions of NKT cells.

Contribution of hippocampal place cell activity to learning and formation of goal-directed navigation in rats

Although extensive behavioral studies have demonstrated that hippocampal lesions impair navigation toward specific places, the role of hippocampal neuronal activity in the development of efficient navigation during place learning remains unknown. The aim of the present study was to investigate how hippocampal neuronal activity changes as rats learn to navigate efficiently to acquire rewards in an open field. Rats were pre-trained in a random reward task where intracranial self-stimulation rewards were provided at random locations. Then, the rats were trained in a novel place task where they were rewarded at two specific locations as they repeatedly shuttled between them. Hippocampal neuronal activity was recorded during the course of learning of the place task. The rats learned reward sites within several sessions, and gradually developed efficient navigation strategies throughout the learning sessions. Some hippocampal neurons gradually changed spatial firing as the learning proceeded, and discharged robustly near the reward sites when efficient navigation was established. Over the learning sessions, the neuronal activity was highly correlated to formation of efficient shuttling trajectories between the reward sites. At the end of the experiment, spatial firing patterns of the hippocampal neurons were re-examined in the random reward task. The specific spatial firing patterns of the neurons were preserved if the rats navigated, as if they expected to find rewards at the previously valid locations. However, those specific spatial firing patterns were not observed in rats pursuing random trajectories. These results suggest that hippocampal neurons have a crucial role in formation of an efficient navigation.

Regression of an unresectable pancreatic tumor following nonmyeloablative allogeneic peripheral-blood stem-cell transplantation

A 59-year-old female with an unresectable, large pancreatic tumor (10.0 x 8.0 cm(2) on CT scan) underwent nonmyeloablative allogeneic peripheral-blood stem-cell transplantation from her HLA-identical sibling. Pronounced tumor regression and relief from pain without acute graft-versus-host disease (GVHD) were observed following transplantation. The patient is surviving (more than 300 days) after transplantation, with extensive chronic GVHD, and has tumor regression with an 80% reduction in tumor size. The observed clinical course may suggest a graft-versus-tumor effect on the pancreatic tumor following allogeneic stem-cell transplantation.

Essential role of the adhesion receptor LFA-1 for T cell-dependent fulminant hepatitis

Viral hepatitis affects more than 2 billion people worldwide. In particular, no effective treatment exists to abrogate death and liver damage in fulminant hepatitis. Activation of T cells is an initial and critical event in the pathogenesis of liver damage in autoimmune and viral hepatitis. The precise molecular mechanisms that induce T cell-mediated hepatocyte injury remain largely unclear. In mice, T cell-dependent hepatitis and acute liver damage can be modeled using ConA. In this study, we examined the role of the adhesion receptor LFA-1 in ConA-induced acute hepatic damage using LFA-1(-/-) (CD11a) mice. Massive liver cell apoptosis and metabolic liver damage were observed in LFA-1(+/+) mice following ConA injection. By contrast, LFA-1(-/-) mice were completely resistant to ConA-induced hepatitis and none of the LFA-1(-/-) mice showed any hepatic damage. Whereas activated hepatic T cells remained in the liver in LFA-1(+/+) mice, activated T cells were rapidly cleared from the livers of LFA-1(-/-) mice. Mechanistically, T cells from LFA-1(-/-) mice showed markedly reduced cytotoxicity toward liver cells as a result of impaired, activation-dependent adhesion. Importantly, adoptive transfer of hepatic T cells from LFA-1(+/+) mice, but not from LFA-1(-/-) mice, sensitized LFA-1(-/-) mice to ConA-induced hepatitis. Thus, LFA-1 expression on T cells is necessary and sufficient for T cell-mediated liver damage in vivo. These results provide the first genetic evidence on an adhesion receptor, LFA-1, that has a crucial role in fulminant hepatitis. These genetic data identify LFA-1 as a potential key target for the treatment of T cell-mediated hepatitis and the prevention of liver damage.

Growth of human squamous cell carcinoma xenografts in mice is inhibited by local angiostatin gene therapy

The possibility of inhibiting tumor growth by blocking the formation of new tumor vessels has recently received attention. Antiangiogenic tumor therapies have recently attracted intense interest because of their direct endothelial targeting and the absence of drug resistance. Local antiangiogenic gene therapy for cancer offers a potential way to achieve sustained therapeutic release of antiangiogenic substances. As a step toward this goal, we used liposomes complexed to angiostatin cDNA and targeted to human squamous cell carcinoma cell lines in vivo. Tumor cells expressing angiostatin after local gene transfer showed markedly reduced vascularity and contained many apoptotic tumor cells. These results demonstrate the potential utility of liposome-derived angiostatin for adjuvant therapy of oral cancer in humans.

The role of LFA-1 in osteoclast development induced by co-cultures of mouse bone marrow cells and MC3T3-G2/PA6 cells

Interactions between leukocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) influence the development of osteoclasts. However, little is known about how these adhesion molecules are involved in the process of osteoclast development. This study evaluated the role of LFA-1 and its ligands in osteoclast development and bone resorption. Co-cultures of bone marrow cells from LFA-1-deficient mice and MC3T3-G2/PA6 (PA6) cells were cultured in the presence of 1alpha,25(OH)2D3 and dexamethasone for 7 days. The number of TRAP-positive cells that were generated by bone marrow cells from LFA-1-deficient mice was smaller than that generated by bone marrow cells from wild-type mice. In addition, the bone-resorbing activity of osteoclast-like cells that were generated from LFA-1-deficient mice was lower than that generated by osteoclast-like cells from wild-type mice. Immunofluorescence flow cytometry showed that osteoclast stromal PA6 cells expressed the cell adhesion molecules, ICAM-1 and VCAM-1. When monoclonal antibodies to mice VCAM-1, CD11b or CD18 were added separately to the co-culture system, the number of TRAP-positive cells that were generated from LFA-1-deficient mice was 20-30% smaller than that generated from wild-type mice. The formation of TRAP-positive cells from both LFA-1 deficient and wild-type mice was especially inhibited by anti-CD18 antibody, in comparison to the addition of normal IgG serum. These results suggest that LFA-1 adhesion molecules play a role in osteoclast development by affecting adhesion between stromal cells and osteoclast progenitors before the occurrence of ODF-ODF receptor signaling. CD18 appears to be a key adhesion molecule in cell-to-cell contacts during the early stage of osteoclast development.

Cancer therapy by gene therapy with angiostatin

Angiostatin, an internal fragment of plasminogen, has been shown to inhibit angiogenesis. A new area of cancer research that has generated excitement is the use of angiostatin to treat cancer. Angiostatin protein therapy has not been pursued because current technology is inadequate to manufacture the needed biologically active proteins in sufficient quantities. It is sufficient for effective therapy with angiostatin to establish angiostatin production in the vicinity of tumors by gene transfer of angiostatin cDNA. There are various methods by which to transfer angiostatin cDNA. One way is to use a viral vector to incorporate the gene into cells. Another way is to use nonviral vectors. In this review, evidence accumulated from many laboratories suggests that angiostatin gene therapy may be an important new cancer therapy as an adjuvant therapy to prevent recurrence. (c) 2001 Prous Science. All rights reserved.

The stress kinase mitogen-activated protein kinase kinase (MKK)7 is a negative regulator of antigen receptor and growth factor receptor-induced proliferation in hematopoietic cells

The dual specificity kinases mitogen-activated protein kinase (MAPK) kinase (MKK)7 and MKK4 are the only molecules known to directly activate the stress kinases stress-activated protein kinases (SAPKs)/c-Jun N-terminal kinases (JNKs) in response to environmental or mitogenic stimuli. To examine the physiological role of MKK7 in hematopoietic cells, we used a gene targeting strategy to mutate MKK7 in murine T and B cells and non-lymphoid mast cells. Loss of MKK7 in thymocytes and mature B cells results in hyperproliferation in response to growth factor and antigen receptor stimulation and increased thymic cellularity. Mutation of mkk7 in mast cells resulted in hyperproliferation in response to the cytokines interleukin (IL)-3 and stem cell factor (SCF). SAPK/JNK activation was completely abolished in the absence of MKK7, even though expression of MKK4 was strongly upregulated in mkk7(-/-) mast cell lines, and phosphorylation of MKK4 occurred normally in response to multiple stress stimuli. Loss of MKK7 did not affect activation of extracellular signal-regulated kinase (ERK)1/2 or p38 MAPK. mkk7(-/-) mast cells display reduced expression of JunB and the cell cycle inhibitor p16INK4a and upregulation of cyclinD1. Reexpression of p16INK4a in mkk7(-/-) mast cells abrogates the hyperproliferative response. Apoptotic responses to a variety of stimuli were not affected. Thus, MKK7 is an essential and specific regulator of stress-induced SAPK/JNK activation in mast cells and MKK7 negatively regulates growth factor and antigen receptor-driven proliferation in hematopoietic cells. These results indicate that the MKK7-regulated stress signaling pathway can function as negative regulator of cell growth in multiple hematopoietic lineages.

Transverse colonic cancer presenting as an anterior abdominal wall abscess: report of a case

An 81-year-old man who had been aware of a right anterior abdominal mass for 1 week was admitted to our hospital on July 3, 1999, after the mass had perforated and was secreting mucinous purulent material. Computed tomography clearly showed an anterior abdominal wall abscess and a large intraabdominal tumor that contained a fistula-like structure. Barium enema revealed an apple-core sign at the transverse colon, with a fistula that connected the colon to the abscess cavity. Transverse colonic cancer complicated by an anterior abdominal wall abscess was diagnosed, and an extended right hemicolectomy was performed. We did not perform en bloc excision of the full thickness of the anterior abdominal wall, including the abscess, because the defect was determined to be too large to repair. Thus, when curative resection is not feasible, as in our patient, resection of the primary tumor with en bloc partial resection of the adherent parietal wall should be performed if possible, as this procedure has the potential to improve the postoperative quality of life of the patient.

Angiostatin gene therapy inhibits the growth of murine squamous cell carcinoma in vivo

Tumor growth is an angiogenesis-dependent process and therapeutic strategies aimed at inhibiting angiogenesis are theoretically attractive. Angiostatin has been shown to potently inhibit endothelial proliferation in vitro and tumor growth in vivo. We now show that a shift in the balance of tumor angiogenesis by gene transfer of a cDNA coding for mouse angiostatin into mouse squamous cell carcinoma NRS-1 and SCC-VII cells suppresses tumor growth in vivo. The inhibition of an angiostatin-transfected tumor was accompanied by a marked reduction in vascularity and the presence of many apoptotic tumor cells. However, transfected-angiostatin cDNA does not affect the expression of the vascular endothelial growth factor (VEGF) and VEGF-R2 in the vascular endothelium. The inhibition mechanisms of neovascularization may be mediated independent of VEGF:VEGF-R2 complex. Our data may provide a useful approach for human oral cancer therapy by gene therapy with angiostatin.

Expression pattern of a newt Notch homologue in regenerating newt retina

We isolated part of a newt Notch homologue, N-Notch, from regenerating newt retina. The spatio-temporal pattern of N-Notch expression was studied by in situ hybridization at different stages of newt retinal regeneration. Proliferating cells were confirmed by the injection of bromodeoxyuridine (BrdU). In the early stage of regeneration, when the retina was one to two cells thick, all proliferating retinal progenitors expressed N-Notch. As the thickness of the retina increased with regeneration, N-Notch expression decreased in BrdU-positive cells on the vitreal side of the retina. Subsequently, presumptive retinal ganglion cells that were BrdU-negative cells appeared at the vitreal edge of the regenerating retina. These differentiating cells did not express N-Notch. Later, N-Notch expression decreased in the BrdU-positive cells on the scleral surface of the retina. Subsequently, presumptive photoreceptor cells that were BrdU-negative cells appeared in this region. These differentiating cells also did not express N-Notch. The proliferating retinal progenitors ceased expressing N-Notch and then stopped dividing during the differentiation of ganglion cells and photoreceptor cells. It was found that retinal regeneration involves the expression of an important developmental signaling molecule, Notch, in retinal progenitors and the expression of Notch ceased as cell differentiation proceeded during retinal regeneration.

Quantitative TaqMan PCR without a real-time thermal cycler: an assay for fish insulin-like growth factor I messenger RNA

The reverse transcriptase-polymerase chain reaction, more commonly known as RT-PCR, has become a widely used tool in molecular biology and is now frequently used in monitoring gene expression levels. A number of variations in the RT-PCR technique now exist including TaqMan PCR (5' nuclease assay), which is a useful nonisotopic detection method for the quantification of PCR products. To monitor the formation of these fluorescent amplification products a "real-time" thermal cycler is normally required. In this study, repeated scanning of PCR products in a 96-well plate format showed that a conventional fluorescent plate reader can be used to generate similar results. To demonstrate the power of this approach, the nutritional regulation of insulin-like growth factor I (IGF-I) was investigated in a marine finfish, the snapper (Pagrus auratus). Hepatic IGF-I messenger RNA levels were shown to significantly decrease after 2 weeks of fasting and returned to fed control levels on refeeding. These results demonstrated that a real-time PCR machine was not required to generate this type of quantitative data and that this technology can be adapted for use in most molecular biology laboratories.

Genetic dissection of SecA: suppressor mutations against the secY205 translocase defect

BACKGROUND

The driving force for protein translocation across the bacterial plasma membrane is provided by SecA ATPase, which undergoes striking conformational changes characterized by the membrane insertion and deinsertion cycle. This action of SecA requires the membrane-embedded SecYEG complex. Previously, we have identified a cold-sensitive secY mutation (secY205), affecting the most carboxy-terminal cytosolic domain, that did not allow an ATP-dependent insertion of a SecA-preprotein complex. Thus, this mutant provides an excellent system for genetic analysis of the SecY-SecA interaction.

RESULTS

We carried out a systematic isolation of secA mutations that suppressed secY205 cold-sensitivity. A total of 40 independent suppressor mutations were classified into: (i) allele-specific suppressors, acting only against secY205, and (ii) 'super active' suppressors, acting against almost any sec defects. The former class of mutations, presumably with specific effects on the SecY-SecA interaction, clustered in two regions close to the Walker motif A sequences of the two ATP-binding domains. The latter mutations, enhancing general SecA activities, were mostly in or around the minor ATP-binding domain.

CONCLUSIONS

The Walker motif A regions of SecA are important for the SecA-SecY interaction that leads to the SecA conformational changes required for insertion into the SecYEG channel. The minor ATP-binding domain is important for the down-regulation of SecA activities.

Adhesion mediated by LFA-1 is required for efficient IL-12-induced NK and NKT cell cytotoxicity

Interleukin 12 (IL-12)-activated NK1.1+TCRalpha beta+ (NKT2) and NK1.1+TCRalpha beta- (NK) cells exhibit cytotoxic activity against a wide variety of tumor cells in the absence of prior sensitization. Here we demonstrate that the integrin adhesion receptor LFA-1 (CD11a/CD18) regulates the cytotoxic activity of IL-12-activated NKT and NK cells against YAC-1 and EL-4 tumor cells. Differentiation in vivo and the expression of the cytolytic effector molecules perforin and Fas-L were comparable in both IL-12-activated NKT and NK cells from LFA-1-/ - and LFA-1+/+ mice. However, LFA-1-/-IL-12-activated NKT and NK cells showed impaired conjugate formation with target cells. These results provide the first genetic evidence for a role for an adhesion receptor in killing by IL-12-activated NK cells.

Regulation of T cell activation, anxiety, and male aggression by RGS2

Regulators of G protein signaling (RGS) proteins accelerate the GTPase activity of Galpha protein subunits in vitro, negatively regulating G protein-coupled receptor signaling. The physiological role of mammalian RGS proteins is largely unknown. The RGS family member rgs2 was cloned as an immediate early response gene up-regulated in T lymphocytes after activation. To investigate the role of RGS2 in vivo, we generated rgs2-deficient mice. We show that targeted mutation of rgs2 in mice leads to reduced T cell proliferation and IL-2 production, which translates in an impaired antiviral immunity in vivo. Interestingly, rgs2(-/-) mice also display increased anxiety responses and decreased male aggression in the absence of cognitive or motor deficits. RGS2 also controls synaptic development and basal electrical activity in hippocampal CA1 neurons. Thus, RGS2 plays an important role in T cell activation, synapse development in the hippocampus, and emotive behaviors.

Quantification of optical signals with electrophysiological signals in neural activities of Di-4-ANEPPS stained rat hippocampal slices

We have quantified the optical signals of synaptically induced neural activities in an in vitro brain slice preparation in terms of electrophysiological signals. The qualification was done using electrophysiologically well known neural activities in the CA1 area of rat hippocampal slices stained with externally applied fluorescent voltage-sensitive dye (VSD; Di-4-ANEPPS). Together with a newly designed CCD-based digital high-speed camera system and epi-fluorescent optics, our improvements were made on a protocol for staining using a newly designed chamber system. These improvements enabled us to make stable and reliable recordings of optical signals and electrophysiological measurements without affecting the physiological status and to make a quantitative comparison between them. The time course and amplitude of the optical signal showed fair agreement with intracellular and extracellular recordings, and was stable over 2 h. The optical signal followed synaptically induced long-term potentiation (LTP) as monitored by the electrophysiological signals. A regional difference in the amount of LTP was found in optical signals and was confirmed in the electrophysiological signals. These results demonstrate the capabilities of our improved method as an alternative but more potent tool to measure the neuronal activities of brain slice in addition to electrophysiological method.

Automatic system for the assay of guanidino compounds to assess uremic status

An automated system for HPLC-fluorometry of serum guanidino compounds was constructed. This system accomplished simultaneous removal of protein and uremic fluorescences, abundant in the sera of uremic patients, which interfere with the fluorometric assay. This system was applied to the detailed elucidation of the behavior of guanidinosuccinic acid and methylguanidine during and after hemodialysis therapy (HD). The uremic patients who are capable of excreting urine even under hemodialysis therapy showed low serum guanidinosuccinic acid and methylguanidine levels. The prolongation of the interval between HD for one of the patients capable of excreting urine was examined. The levels of guanidinosuccinic acid and methylguanidine did not significantly increase and no hazardous effect was observed by 2 d of prolongation.

[Isolated tumor cells and micrometastasis--clinical behavior and therapeutic implications]

Recent advances in the detection of both isolated tumor cells and micrometastases in distant organs by means of immunocytochemical and molecular biological techniques have brought a new paradigm for the understanding of cancer biology. For instance, although the presence of a micrometastasis is a significant indicator of poor prognosis, it is now widely accepted that certain residual tumor cells remain dormant for a long period without any treatment. Many investigators have focused on what is different in the nature of the dormant and active tumor cells, and how microtumors can acquire the active phenotype in ectopic distant organs. In addition, information on both isolated tumor cells and micrometastases is useful not only for staging but also for considering an adjuvant treatment schedule. This review summarizes the recent clinical outcomes of the investigations of both isolated tumor cells and micrometastases.

[Antiangiogenesis therapy and hormone therapy--their resemblance and applications of prognostic and predictive factors]

Many new ideas to control tumor angiogenesis are now being tested in clinical trials. In considering strategies for clinical development of antiangiogenesis treatment, that of endocrine therapy might be particularly useful as a model. Endocrine therapy is a unique treatment used only for hormone-dependent tumors; however, its clinical fruits are exceptional in the entire history of cancer therapy. It is now clearly proven that long-term continuous treatment with antihormones brings a magnificent survival benefit for primary breast cancer patients. This benefit is tumor-phenotype oriented, where the hormone receptor is characterized as a potent predictive factor. Antiangiogenesis treatments seem to have several similarities with endocrine therapy, in that both treatments are cytostatic, stroma-targeting, time-dependent and less effective for large tumor burdens. A combination effect with chemotherapy is often observed with both treatments, at least in animal experiments. In a sense, anti-oncogene product therapy follows endocrine therapy in clinical development. Although antiangiogenesis treatments should be developed based on original concepts, the successful experience of endocrine therapy may provide many hints for the development of antiangiogenesis therapy.

Characterization of a mutant form of SecA that alleviates a SecY defect at low temperature and shows a synthetic defect with SecY alteration at high temperature

The secY205 mutant is cold-sensitive for protein export, with an in vitro defect in supporting ATP- and preprotein-dependent insertion of SecA into the membrane. We characterized SecA81 with a Gly516 to Asp substitution near the minor ATP-binding region, which suppresses the secY205 defect at low temperature and exhibits an allele-specific synthetic defect with the same SecY alteration at 42 degrees C. The overproduced SecA81 aggregated in vivo at temperatures above 37 degrees C. Purified SecA81 exhibited markedly enhanced intrinsic and membrane ATPase activities at 30 degrees C, while it was totally inactive at 42 degrees C. The trypsin digestion patterns indicated that SecA81 has some disorder in the central region of SecA, which encompasses residues 421-575. This conformational abnormality may result in unregulated ATPase at low temperature as well as the thermosensitivity of the mutant protein. In the presence of both proOmpA and the wild-type membrane vesicles, however, the thermosensitivity was alleviated, and SecA81 was able to catalyze significant levels of proOmpA-stimulated ATP hydrolysis as well as proOmpA translocation at 42 degrees C. While SecA81 was able to overcome the SecY205 defect at low temperature, the SecY205 membrane vesicles could not significantly support the translocation ATPase or the proOmpA translocation activity of SecA81 at 42 degrees C. The inactivated SecA81 molecules seemed to jam the translocase since it interfered with translocase functions at 42 degrees C. Based on these results, we propose that under preprotein-translocating conditions, the SecYEG channel can stabilize and activate SecA, and that this aspect is defective for the SecA81-SecY205 combination. The data also suggest that the conformation of the central region of SecA is important for the regulation of ATP hydrolysis and for the productive interaction of SecA with SecY.

A mutation in secY that causes enhanced SecA insertion and impaired late functions in protein translocation

A cold-sensitive secY mutant (secY125) with an amino acid substitution in the first periplasmic domain causes in vivo retardation of protein export. Inverted membrane vesicles prepared from this mutant were as active as the wild-type membrane vesicles in translocation of a minute amount of radioactive preprotein. The mutant membrane also allowed enhanced insertion of SecA, and this SecA insertion was dependent on the SecD and SecF functions. These and other observations suggested that the early events in translocation, such as SecA-dependent insertion of the signal sequence region, is actually enhanced by the SecY125 alteration. In contrast, since the mutant membrane vesicles had decreased capacity to translocate chemical quantity of pro-OmpA and since they were readily inactivated by pretreatment of the vesicles under the conditions in which a pro-OmpA translocation intermediate once accumulated, the late translocation functions appear to be impaired. We conclude that this periplasmic secY mutation causes unbalanced early and late functions in translocation, compromising the translocase's ability to catalyze multiple rounds of reactions.

The antiangiogenesis effect of interleukin 12 during early growth of human pancreatic cancer in SCID mice

Interleukin 12 (IL-12) is a heterodimeric cytokine that exerts a potent antitumor effect through its pleiotropic actions. It was recently reported that IL-12 has also a potent antiangiogenic effect through the induction of IFN-gamma, which triggers the production of chemokines such as IP-10 that has been shown to have antiangiogenesis properties. In this study we transfected the IL-12 gene into a human pancreatic adenocarcinoma cell line (PK-1). PK-1 cells transfected with the green fluorescence protein (gfp) gene were used as positive controls. The in vitro growth curve and in vivo tumor growth of transfectants (IL-12/PK-1 and gfp/PK-1) were compared with those of parental cells. The SCID mice used in this study were administered antiasialo GM-1 Ab (100 microg, i.p., twice weekly) to deplete the remaining immunoeffector cells, NK cells. Using a skinfold chamber model, we observed and recorded tumor angiogenesis by intravital microscopy. In vitro growth of IL-12/PK-1 and gfp/PK-1 cells was not different from that of wild-type PK-1 cells (wt/PK-1). However, IL-12 transfected PK-1 cells did not develop into tumors as did the wt/PK-1 cells after subcutaneous inoculation in antiasialo GM-1 Ab administered SCID mice. The growth of IL-12/PK-1 tumors was restored in mice treated with anti-IL-12 antibody. We found that IL-12/PK-1, in contrast to gfp/PK-1 and wt/PK-1, failed to initiate an angiogenic response, as observed in the skinfold chamber model. These results indicate that the antiangiogenesis effect of IL-12 alone, without immune system involvement, is sufficient to block the growth of human pancreatic cancer.

Metastatic colon carcinoma found within an inguinal hernia sac: report of a case

We report herein the case of a patient in whom metastatic colon carcinoma was found within an inguinal hernia sac. According to Lejar's classification, colon carcinomas within inguinal hernias are categorized as intrasaccular- and saccular-type tumors. In our patient, asymptomatic transverse colon carcinoma was the primary lesion, and to the best of our knowledge, this is only the fourth case of such a saccular-type tumor to be reported in the literature. To date, 21 cases of intrasaccular tumors have been reported, and saccular-type tumors are considered to be an even rarer entity, unless the patients have obvious ascites, indicating peritonitis carcinomatosa. Histologic examination of the hernia sac is recommended for male patients of advanced age with an inguinal hernia, especially those who have previously undergone surgery for colorectal carcinoma.

Direct in vitro evidence and in vivo analysis of the antiangiogenesis effects of interleukin 12

As an antitumor agent, interleukin-12 (IL-12) has been revealed to be a key regulator of the immune response, particularly that involving CTL and natural killer (NK) cells. We report herein the antiangiogenesis effect of IL-12 on human as well as murine tumors in NK-depleted severe-combined immunodeficient mice using fibroblasts genetically engineered to secrete this cytokine. Although the in vitro growth of tumor cells was not affected by the presence of IL-12, coinoculation of IL-12-secreting fibroblasts strongly inhibited tumor growth in immunodeficient mice. The neovascularization surrounding the tumor was remarkably inhibited in the area in which the IL-12-secreting fibroblasts were implanted, resulting in the suppression of tumor growth. Lectin staining in tumor sample sections also showed a significant reduction in the number of vessels. The RNA expression of IFN-gamma and its inducible antiangiogenic chemokine IFN gamma-inducible protein 10 was stimulated in endothelial cells cultured with IL-12. It was also found that IL-12 down-regulated the expression of the endothelial cell mitogens vascular endothelial growth factor and basic fibroblast growth factor. The antitumor effects of IL-12 were accompanied by interesting histological changes consisting of a high degree of keratinization and apoptosis and a decrease in the proliferation rate of human tumors and extensive necrosis in the murine ones.

[A case of stage IV (A3) cervical and upper thoracic esophageal adenocarcinoma successfully treated with concurrent chemoradiotherapy]

We report a case of cervical and upper thoracic esophageal adenocarcinoma with tracheal stenosis and bilateral recurrent nerve palsy. A 64-year-old man with unresectable esophageal cancer (A3, N1, M0) was treated with concurrent chemoradiotherapy. A dose of 67.4 Gy was irradiated to the cervical and upper thoracic area where the primary tumor and lymph node metastases were located, and six courses of 5-FU (250 mg/24 h/day 1-5) and CDDP (5 mg/1 h, just before radiation/day 1-5) were delivered concurrently. The esophageal tumor showed a complete response (CR), and the paratracheal lymph node metastases showed partial responses (PR). The reason these therapies were more effective against the tumor than the lymph node metastases is uncertain. The patient is no longer required to stay in the hospital, and his QOL has been improving. His condition has been maintained for 4 months, so this type of concurrent chemoradiotherapy may be recommended for cervical and upper thoracic esophageal adenocarcinoma.

Pax-6 expression during retinal regeneration in the adult newt

The present study examined the expression of Pax-6 during retinal regeneration in adult newts using in situ hybridization. In a normal retina, Pax-6 is expressed in the ciliary marginal zone, the inner part of the inner nuclear layer, and the ganglion cell layer. After surgical removal of the neural retina, retinal pigment epithelial cells proliferate into retinal precursor cells and regenerate a fully functional retina. At the beginning of retinal regeneration, Pax-6 was expressed in all retinal precursor cells. As regeneration proceeded, differentiating cells appeared at the scleral and vitreal margins of the regenerating retina, which had no distinct plexiform layers. In this stage, the expression of Pax-6 was localized in a strip of cells along the vitreal margin of the regenerating retina. In the late stage of regeneration, when the layer structure was completed, the expression pattern of Pax-6 became similar to that of a normal retina. It was found that Pax-6 is expressed in the retinal precursor cells in the early regenerating retina and that the expression pattern of Pax-6 changed as cell differentiation proceeded during retinal regeneration.

The occurrence of apoptosis during retinal regeneration in adult newts

The present study examined the occurrence of apoptosis, identified by an in situ technique for detecting DNA fragmentation, in the regenerating retina of adult newts following ablation of the retina. Apoptosis occurs in the initial phase of regeneration when retinal precursor cells are actively proliferating. In the late stage of regeneration, when two synaptic layers are forming, apoptosis occurs mainly in the ganglion cell layer and inner nuclear layer. We found that apoptosis occurred with proliferation, differentiation, formation of retinal layers and retinotectal projections during retinal regeneration. Our findings suggest that apoptosis is closely related to these phenomena.

The trichothecene biosynthesis regulatory gene from the type B producer Fusarium strains: sequence of Tri6 and its expression in Escherichia coli

A genomic DNA fragment containing Tri6, a transcription activator gene of trichothecene biosynthesis, was cloned by vectorette PCR from Fusarium graminearum F15, which produces type B trichothecene, deoxynivalenol. The nucleotide sequence of the gene showed 84% of identity to that of the type A trichothecene producer Fusarium sporotrichioides NRRL 3299, but the sequence around the initiation codon was not highly conserved between these producers. Based on the upstream and downstream sequences of the coding region of F. graminearum, Tri6 could be amplified by PCR from other type B trichothecene producers. Tri6 appeared to be expressed for only a limited period prior to the toxin production.

Adjuvant immunotherapy using fibroblasts genetically engineered to secrete interleukin 12 prevents recurrence after surgical resection of established tumors in a murine adenocarcinoma model

BACKGROUND

To explore effective therapeutic strategy against cancer of the gastrointestinal tract, tumor vaccination using fibroblasts secreting interleukin-12 (IL-12) was developed as an adjuvant therapy against murine tumor after surgical resection.

METHODS

Initially, IL-12 was genetically engineered into fibroblasts (IL-12/3T3 cells), and then we evaluated in vivo and in vitro antitumor effects. In the vaccination model, irradiated C-26 tumor mass was reinoculated intradermally with IL-12/3T3 cells in mice as a tumor vaccine to examine how much it suppresses tumor recurrence.

RESULTS

IL-12/3T3 cells producing 7.2 ng/10(6) cells/24 h murine IL-12 in vitro exerted dose-dependent potent tumor suppression when coinoculated with C-26 cells in vivo. Specific immunity was also acquired in 63% of mice in vivo. In the vaccination model, protective immunity was developed in 70% of mice that were inoculated with irradiated tumor mass and IL-12/3T3 cells. In addition, local recurrence was not observed in vaccinated mice, although 44% of control mice had recurrence.

CONCLUSIONS

Coinoculation of genetically engineered fibroblasts secreting IL-12 with irradiated tumor mass was proved to be an effective tumor vaccine. This system of vaccination is easily applicable to clinical situations, particularly to human gastrointestinal tract cancers.

Purification and cloning of a thermostable manganese catalase from a thermophilic bacterium

We have purified a heat-stable catalase from a thermophilic bacterium, Thermus species strain YS 8-13. The enzyme was purified 160-fold from crude cellular extracts and possessed a specific activity of 8000 units/mg at 65 degrees C. The purified enzyme displayed the highest activity at pH 7 to 10 and temperatures around 85 degrees C. The catalase was determined to be a manganese catalase, based on results from atomic absorption spectra and inhibition experiments using sodium azide. The enzyme was composed of six identical subunits of molecular weight 36,000. Amino acid sequences determined from the purified protein were used to design oligonucleotide primers, which were in turn used to clone the coding gene. The nucleotide sequence of a 1.4-kb fragment of Thermus sp. YS 8-13 genomic DNA containing a 909-bp open reading frame was determined. The gene encoded a 302-residue polypeptide of deduced molecular weight 33,303. The deduced amino acid sequence displayed a region-specific homology with the sequences of the manganese catalase from a mesophilic organism, Lactobacillus plantarum.

Idiopathic CD4+ T lymphocytopenia disclosed by the onset of empyema thoracis

A 56-year-old man was admitted to our hospital in December 1996 due to empyema thoracis. A laboratory examination revealed lymphocytopenia and CD4+ T lymphocytopenia (<300 cells/ microl). No evidence for a human immunodeficiency virus (HIV) infection was found. No malignant, hematological or autoimmune disease was detected. We thus diagnosed this case as being idiopathic CD4+ T lymphocytopenia (ICL). During his hospital treatment, he was affected with cytomegaloviral retinitis and cured by therapy. His subsequent treatment went well without a recurrence of severe infection although a low CD4+ T lymphocyte count continued after the recovery from empyema thoracis.

Reward-quality dependent anticipation in rat nucleus accumbens

Single unit recording in rat nucleus accumbens (NAcc) was used to ascertain NAcc neuronal activity in mediating of reward including its anticipation. Of the 103 neurons investigated, 63% showed some response in connection with the task activity. Of these, 20 units responded during delivery of the primary reward (food and/or water) and five responded during the time period preceding reward if the reward was delayed (four to food, one to water). These result suggest that NAcc neurons responded not only to the delivery of primary reward and task inducing anticipation of reward, but also represent the difference of reward quality between food and water specifically.