Reduced anterior internal capsule and thalamic volumes in first-episode psychosis.

BACKGROUND: The thalamus is the gateway for sensory and motor information en route to the cortex. Information is processed via thalamocortical and corticothalamic pathways coursing through the internal capsules. In this study, we investigated the relationship between the anterior limb of the internal capsule, posterior limb of the internal capsule, and thalamus in first-episode psychosis (FEP). METHODS: Twenty-nine FEP subjects (26 DSM-IV schizophrenia, 2 schizoaffective disorder, 1 psychosis not otherwise specified) and 22 healthy volunteers participated in this study. Anterior limb of the internal capsule (AIC), posterior limb of the internal capsule (PIC), and the thalamus volumes were manually determined from MRI scans. RESULTS: FEP subjects had reduced AIC volumes (F(1,45)=6.18, p=0.017) and thalamic volumes (F(1,45)=8.00, p=0.007) compared to healthy volunteers. PIC volumes did not differ. Significant correlations between AIC volumes and thalamic volumes were observed in subjects with FEP, but not in healthy volunteers. Negative relationships between thalamic volumes and symptom severity were also observed. CONCLUSIONS: The AIC and thalamic volumes were reduced in subjects with FEP compared to healthy volunteers. Abnormalities in thalamocortical and orticothalamic pathways may contribute to functional disruption of neural circuits in psychosis.

Heme oxygenase activity in term human placenta.

Carbon monoxide (CO) is a novel gaseous chemical messenger, formed during heme oxygenase (HO)-catalysed oxidation of heme. CO is proposed to play a key role(s) in cell function in many organ systems, including vasodilator action in the cardiovascular system. Recently, it has been demonstrated that there is expression of HO protein in the human placenta and this appears to have a regulatory role in placental perfusion. The objective of the present study was to determine HO enzymatic activity in vitro in five different regions of term human placenta. HO activity was determined in the microsomal fraction of tissue homogenate by measuring the rate of formation of CO from heme, using a gas-chromatographic method. HO activity, expressed as nmol CO formed/g tissue wet weight/h, was higher (P< 0.05) in the chorionic plate, chorionic villi, basal plate and chorio-decidua compared with the amnion. The finding that HO enzymatic activity is present in different regions of term human placenta supports the concept that the heme-CO (HO) pathway plays a complementary role with the L -arginine-nitric oxide (nitric oxide synthase) pathway in the regulation of placental haemodynamics.

Changes in homocysteine levels during normal pregnancy.

OBJECTIVE: The objective of this study was to determine the changes in total plasma homocysteine concentration that occur during normal pregnancy. STUDY DESIGN: In this cross-sectional study homocysteine was measured in 155 normal women in the first, second, and third trimesters and in nonpregnant controls. In addition, albumin, serum B12, serum folate, and red blood cell folate concentrations were measured and correlated to homocysteine values. RESULTS: The mean homocysteine concentration (in micromoles per liter) was 5.6 (95% confidence interval 3.9-7.3) at 8-16 weeks' gestation, 4.3 (95% confidence interval 3.5-5.3) at 20-28 weeks' gestation, 5.5 (95% confidence interval 3.3-7.5) at 36-42 weeks' gestation, and 7.9 (95% confidence interval 6.2-9.6) in the nonpregnant control group. Homocysteine was significantly lower in all 3 trimesters of pregnancy compared with nonpregnant controls (P <.001). Homocysteine levels were directly correlated with albumin levels, which decreased during pregnancy. Homocysteine concentrations were decreased in subjects taking folic acid supplementation. CONCLUSION: Serum concentrations of homocysteine decrease during pregnancy. This occurs in association with the physiologic fall in albumin during pregnancy, as well as with folic acid supplementation.

Use of nitroglycerin for uterine relaxation.

Data from human and experimental animal research indicate that nitric oxide (NO), a novel messenger, formed during the nitric oxide synthase-catalyzed oxidation of L-arginine to L-citrulline, is involved in maintaining normal uterine tone during gestation. There are demonstrated and potential benefits of manipulating the L-arginine-NO system during pregnancy. Several recent case reports and case series have described the effective use of nitroglycerin (GTN), a NO donor compound, antenatally, intrapartum, and postpartum for acute uterine relaxation. Therapeutic indications for GTN range from facilitating external cephalic version, difficult vaginal or cesarean section delivery, and manual exploration of the uterus, to its use as a tocolytic. The intravenous regimen of GTN required to obtain the desired degree of uterine relaxation is extremely variable; intravenous bolus doses of 50 micrograms to 500 micrograms GTN with up to three repeated injections of 50 micrograms to 250 micrograms have been reported. Other methods of GTN administration include transdermal patches and sublingual spray. GTN, when used in low doses, may provide safe and effective uterine relaxation with no clinically apparent fetal or maternal adverse effects. However, clinical trials with use of objective methods of evaluating uterine tone and comparing GTN to other tocolytic agents are required before widespread use in advocated.

Clinical evaluation of periodontal ligament anesthesia using a pressure syringe.

Conventional local anesthesia techniques are frequently unsuccessful, particularly for endodontic procedures. Supplementary injections are often necessary; the periodontal ligament injection is useful for this purpose. This study examined the effectiveness of injecting into the periodontal ligament with a pistol-type pressure syringe as a supplemental technique in patients who did not have adequate anesthesia for endodontic therapy. Sixty patients received the supplemental injections and 20 patients were reinjected when the first PDL injection failed. Data were obtained by questionnaire. Percentages were computed and comparisons made by X2 analysis. The conclusions about attaining anesthesia included: --Needle size was not important; overall, 25- and 30-gauge needles were equivalent. --Injecting under strong back-pressure was important; the greatest frequency of success was attained when injecting under pressure. Lack of back-pressure on both mesial and distal surfaces resulted in a significantly lower incidence of anesthesia. Proper positioning of the needle and maintaining this position, to force the anesthetic deep into the periodontium, is apparently an effective way to generate the needed back-pressure. --Strong back-pressure could usually be attained on either or both surfaces. --Reinjection was frequently successful if the first periodontal ligament injection failed. --Overall frequency of success in attaining anesthesia with the pistol-type pressure syringe was 83%. This was determined by including the instances in which reinjection was necessary. --Comparing the results of this study with a previous similar study, the pressure syringe were equally effective for supplementary anesthesia.

Periodontal ligament injection: evaluation of systemic effects.

By means of a pistol-grip syringe, 0.3 ml. of normal saline solution, 2 percent lidocaine with and without 1:100,000 epinephrine, 3 percent mepivicaine, and 1:100,000 epinephrine alone were injected into large adult dogs via the intravenous, intraosseous, intrapulpal, subcutaneous, periodontal, intramuscular, and submucosal, routes. Changes in heart rate, blood pressure, and respiration were recorded in relation to the time of injection. In the quantities injected, normal saline solution, 2 percent lidocaine, and 3 percent mepivicaine had no measurable effect on the systemic parameters, regardless of the site of injection. Injection of 2 percent lidocaine with epinephrine and of epinephrine alone caused transient decreases in blood pressure and increases in heart rate. The results were similar, whether the injections were done intravenously, intraosseously, or periodontally. Systemic changes were not detected when the epinephrine-containing agents were injected intramuscularly, subcutaneously, submucosally, or intrapulpally. These results support the contention that the periodontal injection is intraosseous in nature and that solutions injected by the periodontal technique are rapidly absorbed into the systemic circulation.