Two populations of neurokinin 1 receptor-expressing projection neurons in lamina I of the rat spinal cord that differ in AMPA receptor subunit composition and density of excitatory synaptic input.

Lamina I of the spinal cord contains many projection neurons that express the neurokinin 1 receptor (NK1r). It has been reported that these cells can undergo long-term potentiation (LTP), which may result from insertion of AMPA-type glutamate receptors (AMPArs) containing GluA1 or GluA4 subunits. We therefore investigated synaptic AMPAr expression on these cells with immunocytochemistry following antigen-retrieval. We also examined their density of glutamatergic input (by analysing AMPAr synaptic puncta and contacts from glutamatergic boutons), and phosphorylation of extracellular signal-regulated kinases (pERKs) following noxious stimulation. Our results indicate that there are two populations of NK1r-expressing projection neurons: large GluA4(+)/GluA1(-) cells with a high density of glutamatergic input and small GluA1(+)/GluA4(-) cells with a much lower input density. Results from pERK experiments suggested that the two groups may not differ in the types of noxious stimulus that activate them. Glutamatergic synapses on distal dendrites of the large cells were significantly longer than those on proximal dendrites, which presumably compensates for the greater attenuation of distally-generated excitatory postsynaptic currents (EPSCs). Both types of cell received contacts from peptidergic primary afferents, however, on the large cells these appeared to constitute over half of the glutamatergic synapses, and were often associated with elongated AMPAr puncta. This suggests that these afferents, which probably contain substance P, provide a powerful, secure synaptic input to large NK1r-expressing projection neurons. These results demonstrate the importance of GluA4-containing AMPArs in nociceptive transmission and raise the possibility that different forms of LTP in lamina I projection neurons may be related to differential expression of GluA1/GluA4.

Soma size distinguishes projection neurons from neurokinin 1 receptor-expressing interneurons in lamina I of the rat lumbar spinal dorsal horn.

Lamina I of the spinal dorsal horn contains neurons that project to various brain regions, and approximately 80% of these projection cells express the neurokinin 1 receptor (NK1r), the main receptor for substance P. Two populations of NK1r-immunoreactive neurons have been identified in lamina I: small weakly immunoreactive cells and large cells with strong immunolabelling [Cheunsuang O and Morris R (2000) Neuroscience 97:335-345]. The main aim of this study was to test the hypothesis that the large cells are projection neurons and that the small cells are interneurons. Projection neurons were identified by injection of tracers into the caudal ventrolateral medulla and lateral parabrachial area, and this was combined with immunostaining for NK1r. We found a bimodal size distribution for NK1r-immunoreactive neurons. The small cells (with somatic cross-sectional areas <200 microm(2)) showed weak immunoreactivity, while immunostaining intensity was variable among the large cells. Virtually all (99%) of the immunoreactive cells with soma areas >200 microm(2) were retrogradely labelled, while only 10% of retrogradely labelled cells were smaller than this. Soma sizes of retrogradely labelled neurons that lacked NK1r did not differ from those of NK1r-expressing projection neurons. It has been suggested that a population of small pyramidal projection neurons that lack NK1r may correspond to cells activated by innocuous cooling, and we therefore assessed the morphology of retrogradely labelled cells that were not NK1r-immunoreactive. Fifteen percent of these were pyramidal, but these did not differ in size from pyramidal NK1r-immunoreactive projection neurons. These results confirm that large NK1r-immunoreactive lamina I neurons are projection cells, and suggest that the small cells are interneurons. Since almost all of the NK1r-immunoreactive cells with soma size >200 microm(2) were retrogradely labelled, cells of this type can be identified as projection cells in anatomical studies.

Managing bruxism and temporomandibular disorders using a centric relation occlusal device.

This article discusses the rationale, indications, and fabrication of the centric relation occlusal (CRO) device in the management of bruxism and temporomandibular disorders. Five methods of fabricating occlusal devices are briefly discussed. Two methods, preferred by the authors, are discussed in detail, including the laboratory phase. One method uses heat-cured acrylic resin, and the other method uses a heat-vacuum machine, thermoplastic splint resin material, and autopolymerizing clear acrylic resin. The use of the CRO device in the successful management of bruxism and temporomandibular disorders has been previously documented in the literature. Some patients may not successfully adjust to the wearing of occlusal devices (splints), which are not well-defined in terms of occlusal morphology, anterior guidance, and their relativity to centric relation. This problem usually is overcome when the dentist uses precise skill in the fabrication and delivery of a CRO device with mutually protected articulation.

Hyperlipidemia and obesity among diabetics at jubail miiltary hospital.

OBJECTIVE: Evaluate the pattern of dyslipidemia and obesity among diabetics, attending the Primary Care Clinic. SUBJECTS AND METHODS: All diabetics (282) registered in the Primary Care Clinic of the Armed Forces Hospital at King Abdulaziz Naval Base, Jubail, Eastern Saudi Arabia, were interviewed by primary care doctors. Weight and height were recorded; fasting blood glucose and cholesterol levels were measured after 12-hour fasting. RESULTS: The study revealed that among 89.7% type 2 and 10.3% type 1 diabetes mellitus, 22.7% had a normal Body Mass Index (BMI) 40.8% were overweight, and 36.5%, obese. Females had a significantly higher BMI than males (P<0.001). Total cholesterol was more than normal in 26%, LDL in 27% and Triglycerides in 11% but HDL lower than normal in 38%. However, mixed hyperlipidemia was seen in 5% of the study population. CONCLUSION: Obesity and dyslipidemia were high among diabetic patients and special attention is required in prevention and treatment.

Parasitic and bacterial infestation among food handlers in jubail, eastern region of saudi arabia.

OBJECTIVE: To evaluate the prevalence of parasitic and bacterial infestations among food handlers. DESIGN: Retrospective study. SETTING: Food handlers working in the Military food serving facilities in Jubail (Eastern Province of Saudi Arabia). METHOD: The stool samples of 881 food handlers of different nationalities were examined at the Armed Forces Hospital laboratory using the concentration method. RESULTS: A total of 194 (20%) of the workers tested positive for enteric microbial infestation. Helminths were the most prevalent, infecting 93 (10.56%) of the food handlers; followed by protozoa which affected 65 (7.38%) food handlers; and the smallest group was infected with bacteria in 44 (4.9%) of the food handlers. Not only single organism infection was seen (83.94%), but also double (14.51%) and triple (1.55%) infections. Among the Helminths, Ascaris lumbricoides was the most prevalent with 33 (47.14%) cases, Giardia lamblia was the most prevalent Protozoa with 23 (43.40%) cases, and Salmonella was the most prevalent bacteria with 34 (87.18%) cases. Expatriates from South Asia showed a significant rate of infection when compared to expatriates from Arabian countries. The Bangladeshi food handlers were of the greatest prevalence of infection with 151 (17.14%) cases, followed by Indian workers with 17 (1.93%) cases, and Pakistani workers with 11 (1.25%). CONCLUSION: The study stresses the importance of regular check-ups and prompt treatment of infected food handler.