Disuse bone loss in hindquarter suspended rats: partial weightbearing, exercise and ibandronate treatment as countermeasures.

The purpose of this study was to evaluate potential countermeasures for bone loss during long-term space missions in the hindquarter suspended rat, including partial weight bearing (surrogate for artificial gravity) episodic full weight bearing (2 hour/day full weight bearing) and treatment with the third generation bisphosphonate ibandronate (Roche). Graded mechanical loading was studied by housing the animals on a novel servo controlled force plate system which permitted the titration of mechanical force at varying frequency and amplitude and different levels of weight bearing. The force plate, which forms the cage floor, is a glass platform supported by an 18" diameter speaker cone filled with expanding polyurethane foam. An infrared optical sensor attached to the speaker cone yields a voltage linearly related to vertical displacement of the glass platform. The dynamic force on the paw was computed as a product of the apparent mass of the animal on the platform at rest and the acceleration of the platform determined from the second derivative of the optical sensor output. The mass of the animal on the platform was varied by adjusting tension on the tether suspending the animal. Mechanical impact loading was titrated with the force plate resonating at different frequencies, including 3 Hz and 16 Hz.

Molecular phylogenetics of Fouquieriaceae: evidence from nuclear rDNA ITS studies.

Molecular sequence data from the 18S-26S rDNA internal transcribed spacer (ITS) region support the monophyly of Fouquieria sensu lato (Fouquieriaceae) and the three subgenera (subg. Fouquieria, subg. Bronnia, subg. Idria) previously recognized within it. Resolution within subg. Fouquieria differs somewhat between parsimony and maximum likelihood (ML) trees. Section Fouquieria and sect. Ocotilla within subg. Fouquieria are not well supported as monophyletic groups. Uncertainty regarding placement of the root within Fouquieriaceae makes discussion of character evolution within the family difficult. Three root positions are consistent with rate-constant evolution of ITS sequences: (1) along the branch to subg. Idria, (2) along the branch to subg. Bronnia, and (3) along the branch to subg. Fouquieria. The first root position listed is equivalent to an outgroup rooting. The third root position listed is equivalent to a midpoint rooting. Of the three root positions above, only the third is along a branch that may be sufficiently long to act as a long-branch attractor. The first two root positions would result in character reconstruction suggesting that succulent growth forms and white floral pigmentation are ancestral within the family, with shifts to woody growth forms and to red floral pigmentation. The third root position results in equivocal reconstruction of the ancestral growth form, equivocal reconstruction of ancestral floral pigmentation in parsimony trees, and a suggestion of white floral pigmentation as ancestral in ML trees. Two previous hypotheses of polyploid origins are compatible with the molecular data presented here: (1) origin of the tetraploid F. diguetii from F. macdougalii, and (2) allopolyploid origin of the hexaploid F. burragei from the tetraploid F. diguetii and a diploid species similar to F. splendens. Direct descent of the hexaploid F. columnaris from the subg. Bronnia lineage is not supported by our data. An amphiploid origin of F. columnaris involving a member of the subg. Bronnia lineage and an extinct taxon outside subg. Bronnia, however, cannot be ruled out.

Non-invasive measurement of cardiac output during coronary artery bypass grafting.

OBJECTIVE: A new device, using whole body bioresistance measurements and a new equation for calculating stroke volume has been developed. Using this equation, an attempt was made to correlate whole body bioresistance cardiac output with thermodilution cardiac output in patients undergoing coronary artery bypass grafting. METHODS: Thirty-one adults undergoing elective coronary artery bypass grafting were studied prospectively. Simultaneous paired cardiac output measurements by whole body bioresistance and thermodilution were made at five time points during coronary artery bypass grafting: in anesthetized patients before incision (T1), after sternotomy (T2), after opening the pericardium (T3), ten min post bypass (T4), and in the intensive care unit (T5). The patients had a mean of three thermodilution cardiac outputs compared with a mean of three bioimpedance measurements at each time point. The bias and precision between the methods were calculated. RESULTS: There was good correlation between bioresistance cardiac output (nCO) and thermodilution cardiac output (ThCO) measurements in both groups for all recorded times. The patients' mean ThCO and nCO, as well as bias and precision between methods were calculated. Mean ThCO ranged between 4.14 and 5.06 l/min; mean nCO ranged between 4.12 and 4.97 l/ min. Bias calculations ranged between -0.072 and 0.104 l/min. Precision (2 SD) calculations ranged between 0.873 and 1.228 l/min for 95% confidence intervals. Pearson's correlation ranged from 0.919 to 0.938. CONCLUSIONS: Cardiac output measured with the new device correlates well with the thermodilution measurements of cardiac output during and immediately following coronary artery bypass grafting. The overall agreement between the two methods was good. The new device is an accurate non-invasive method of measuring cardiac output during coronary artery bypass grafting.

Comparative study of the phonology of preschool children prenatally exposed to cocaine and multiple drugs and non-exposed children.

Cocaine and multiple drug abuse among young adults has spawned research interest in fetal exposure and the sequela of that exposure during the formative developmental years. Previous study of the language development of exposed children has not specifically addressed phonological acquisition. In the present study, the speech of 25 children prenatally exposed to cocaine and multiple drugs was analyzed and compared to that of 25 children who were not prenatally exposed to determine if differences were evident in their phonological patterns. The children ranged in age from 22 months to 51 months. The number and type of phonological processes produced, number of utterances needed to produce a 50-word sample, number of unintelligible words produced, and Home Observation for Measurement of the Environment (HOME) scores were recorded and analyzed. The use of cocaine and multiple drugs during pregnancy was associated with an increase in the use of phonological processes.

High dose neostigmine treatment of malignant sinus tachycardia.

Sinus tachycardia caused by circulating catecholamines in the setting of congestive heart failure may impair systemic perfusion because of decreased diastolic filling time. We report the case of a patient with Wolff-Parkinson-White syndrome with angina and cardiogenic shock who improved dramatically following administration of neostigmine. Cardiac output, blood pressure, and stroke volume increased as heart rate was reduced. A previous attempt at heart rate control, in the same patient, using a low dose beta-antagonist, precipitated hemodynamic collapse. The remarkable recovery of our patient suggests that acetylcholinesterase inhibitors may warrant further investigation in patients with severe sinus tachycardia.

Efficacy of autologous fresh whole blood or platelet-rich plasma in adult cardiac surgery.

BACKGROUND: Transfusing fresh autologous blood during cardiac surgery may improve hemostasis and decrease the need for transfusion. STUDY DESIGN AND METHODS: A prospective randomized study was performed with fresh whole blood (WB) obtained by intraoperative hemodilution (IH) and with platelet-rich plasma (PRP) obtained by perioperative apheresis from adult cardiac surgery patients. RESULTS: Seventy patients were randomly assigned to three arms: 24 to the PRP arm, 18 to the IH arm, and 28 to serve as controls. A mean of 924 +/- 130 mL of WB was collected from the IH group, and a mean of 650 +/- 124 mL of PRP was collected from the PRP group (mean, 1.42 +/- 0.74 x 10(11) platelets); these components were transfused after bypass. Preoperative measures were similar among groups. Intraoperatively, the groups did not differ in bypass time, estimated blood loss, number of transfusions, or proportion receiving transfusion(s). Postoperatively, control patients had more mediastinal drainage (736 mL vs. 476 mL [IH] and 463 mL [PRP]; p = 0.014), but there was no difference in the proportion of patients requiring red cell transfusion (p = 0.87), the hemoglobin at discharge (p = 0.20), or the length of hospitalization (p = 0.57). CONCLUSION: Although a hemostatic benefit manifested as reduced postoperative bleeding was observed, this study does not support the use of fresh blood components obtained by IH or PRP collection during low-risk cardiac surgery. Additional studies are needed to assess whether more aggressive component collection or the use of these techniques in high-risk cases may have a greater impact on clinical outcome variables, including transfusion.

Protamine and left ventricular function: a transesophageal echocardiography study.

The effect of protamine sulfate on left ventricular function was evaluated in 23 patients undergoing heart surgery requiring cardiopulmonary bypass (CPB). Ventricular function was assessed by measuring cardiac index with a thermodilution pulmonary artery catheter and fractional shortening with transesophageal echocardiography (TEE). After CPB, a heparin-neutralizing dose of protamine was infused continuously for 5 min. Hemodynamic variables were obtained and fractional shortening was measured before protamine administration (time 0), during protamine infusion (2.5 and 5 min), and after the infusion (10 and 15 min after the start of protamine). Patients with a preoperative ejection fraction > or = 50% had no statistically significant changes in either cardiac index or fractional shortening with protamine administration, when compared to time 0. However, patients with a preoperative ejection fraction < 50% had a significant decrease in fractional shortening which occurred during and immediately after protamine administration when compared to time 0 (P < 0.01), with no associated change in hemodynamics. Our results suggest that protamine may have a negative inotropic effect that is apparent in patients with impaired ventricular function.

The mechanical control system of bone in weightless spaceflight and in aging.

Bone loss is notable in elderly persons and in astronauts returning from spaceflight, however, the bone changes in these radically different patient populations appear morphologically similar. Bone structure depends upon several independent basic processes: growth, modeling, and remodeling. Each process follows a stereotyped sequence of steps. Alteration of any step may yield a similar bone loss, although from an entirely different mechanism. Mechanical forces appear to coordinate the fundamental bone shaping processes by a negative feedback control system. Determining how mechanical signals control the mass, architecture, and strength of bone may establish the limits by which exercise can prevent osteoporosis in the elderly and in astronauts despite obvious differences in etiology.

Fiber-optic temperature sensing with ultrathin silicon étalons.

We report fiber-optic temperature sensing with an optically thin silicon étalon. A simple fabrication technique by direct deposition of silicon onto the fiber tip, a wide range of operating wavelengths from 1500 nm down to 800 nm, and the applicability for temperature sensing well above 400 degrees C are the most prominent features of the silicon étalon sensor.