Biomedical subjects

A J Thomas

Publications and source records attributed to A J Thomas.

At least 73 records · Page 4Linked to original sources

PubMed1997

Factors associated with the quality before freezing and after thawing of sperm obtained by microsurgical epididymal aspiration.

OBJECTIVE: To identify whether the cause, site of ductal obstruction, and characteristics of fluid aspirates are associated with the cryosurvival and fertility after thawing of sperm obtained during reconstruction of the excurrent ducts with microsurgical epididymal sperm aspiration, vasal sperm aspiration, or both. DESIGN: Prospective study. SETTING: Andrology center at a tertiary care institution. PATIENT(S): Men undergoing reconstruction of the excurrent duct and sperm aspiration (n = 42) or microsurgical epididymal sperm aspiration (n = 11). INTERVENTION(S): Sperm were tested for an association with the cause and site of obstruction. Fertilization and pregnancy rates after sperm aspiration and intracytoplasmic sperm injection (ICSI) were evaluated for fresh and frozen aspirates. MAIN OUTCOME MEASURE(S): Motile sperm count and percentage motility after thawing. RESULT(S): The motile sperm count before freezing was significantly higher in the caput epididymis than in the corpus. The motile sperm count before freezing was related inversely to the distance from the caput where the sperm were aspirated. Sperm from clear and opaque fluid aspirates had better percent motility than those from cloudy and creamy fluid aspirates. High fertilization and pregnancy rates were achieved using both fresh and frozen epididymal sperm. CONCLUSION(S): None of the factors studied was associated with cryosurvival of aspirated epididymal or vasal spermatozoa. Because motility is low after thawing, these specimens are best used with ICSI.

Adult↗

PubMed1997

Seminal reactive oxygen species and sperm motility and morphology in men with spinal cord injury.

OBJECTIVE: To assess the generation of reactive oxygen species and its relation to semen characteristics in men with spinal cord injury. DESIGN: Cross-sectional study. SETTING: Andrology laboratory at a tertiary care facility and research laboratory at a major medical center. PATIENT(S): Men with spinal cord injury and normal men. INTERVENTION(S): Collecting ejaculates from men with spinal cord injury by electroejaculation and vibratory stimulation and from normal men by masturbation. MAIN OUTCOME MEASURE(S): Measurement of reactive oxygen species before and after stimulation with 50 microM N-formyl-methionyl-leucylphenylalanine (FMLP) and 100 nM 12-myristate 13-acetate phorbol ester (PMA), white blood cell (WBC) concentration, sperm motility and morphology, and ejaculation method. RESULT(S): Compared with controls, levels of reactive oxygen species in men with spinal cord injury were significantly higher in unstimulated, f-MLP-stimulated, and PMA-stimulated specimens. The WBC concentration was significantly elevated in patients with spinal cord injury. Sperm motility in men with spinal cord injury was inversely related to the level of reactive oxygen species. The percentage of morphologically normal spermatozoa was significantly lower in men with spinal cord injury. Levels of seminal reactive oxygen species did not differ when comparing specimen type (antegrade versus retrograde) or method of ejaculation in men with spinal cord injury. CONCLUSION(S): Men with spinal cord injury had elevated levels of reactive oxygen species in their semen. Levels of reactive oxygen species were negatively correlated with sperm motility. Levels of reactive oxygen species were independent of the method of ejaculation or the type of specimen.

Adult↗

PubMed1997

Effects of cancer on spermatozoa quality after cryopreservation: a 12-year experience.

OBJECTIVE: To determine whether type of cancer and response to treatment was related to prefreeze or post-thaw semen quality and to predict post-thaw sperm motility from prefreeze motility. DESIGN: Retrospective study. SETTING: Tertiary care institution. PATIENT(S): One hundred six cancer patients cryopreserving their semen specimens. INTERVENTION(S): Computer-assisted semen analysis was performed before and after cryopreservation on each patient specimen. MAIN OUTCOME MEASURE(S): The relationship of sperm motility and motion characteristics to type of cancer and patient's response to treatment. RESULT(S): Prefreeze and post-thaw semen quality did not differ between patients presenting with testicular cancer and Hodgkin's disease. Patients with leukemia or advanced soft tissue cancer had a higher prefreeze and post-thaw motility and higher total and motile sperm count than testicular and Hodgkin's disease patients. A prefreeze sperm motility of > or = 15% could predict a post-thaw motility of > 10%. CONCLUSION(S): Prefreeze or post-thaw semen quality in cancer patients is not affected (except the prefreeze motile sperm count within the testicular cancer patients) by the type of disease. Prefreeze motility can predict post-thaw motility. Cryopreservation of semen should be offered to cancer patients irrespective of the type of disease.

Adult↗

PubMed1997

Fibrin-glue assisted vasoepididymostomy: a comparison to standard end-to-side microsurgical vasoepididymostomy in the rat model.

PURPOSE: The use of fibrin glue for vasovasostomy has produced high patency rates in animal models. Vasoepididymostomy is a microsurgical technique that might be made easier if fibrin glue could substitute for microsutures. We evaluated the efficacy of a new vasoepididymostomy technique using fibrin glue. MATERIALS AND METHODS: Bilateral vasoepididymostomies were performed in 24 male Sprague-Dawley rats using a conventional microsurgical technique on one side and a fibrin-glue assisted technique on the other. The rats were sacrificed 30 days after surgery and anastomotic patency was assessed by examining the vasal fluid for sperm, injecting methylene blue dye into the vas deferens and observing backflow into the epididymis by gross inspection and histological studies. Additionally, the incidence of granuloma formation was compared between the two techniques. RESULTS: Fibrin-glue anastomoses showed a patency rate of 79% (n = 19), compared with 63% (n = 15) for the conventional suture anastomoses (p = 0.29). Among the patent anastomoses, the incidence of sperm granuloma formation between the sutured (12, 50%) and the fibrin glue anastomoses (16, 67%) did not differ significantly (p = 0.36). Morphological tissue changes were similar for the two techniques. The time required for anastomosis using fibrin glue was significantly shorter than the conventional suture technique (p < 0.001). CONCLUSIONS: Conventional suturing techniques for vasoepididymostomy require advanced microsurgical skills. The use of fibrin glue simplifies this procedure and provides patency rates comparable to microsutured, end-to-side anastomoses.

Animals↗

PubMed1997

Vasoepididymostomy for vasectomy reversal: a critical assessment in the era of intracytoplasmic sperm injection.

PURPOSE: We compared vasoepididymostomy to microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection for treatment of epididymal obstruction secondary to vasectomy. MATERIALS AND METHODS: Results in patients who underwent vasoepididymostomy for vasectomy reversal at our institution were compared to those reported previously for microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection performed for obstructive azoospermia. The pregnancy rates, delivery rates, complications, cost per procedure and cost per delivery were compared. A cost per newborn analysis was performed using pregnancy and delivery rates, and reported cost estimates for the complications of assisted reproductive techniques. RESULTS: A total of 55 men underwent 58 vasoepididymostomies in an attempt to restore fertility after vasectomy. Median followup was 19 months (range 0 to 115). Median obstructive interval was 12 years. There were no major complications. The patency rate after 6 months was 85%. Of the couples 20 achieved 24 pregnancies and 16 had 17 live births. The pregnancy rate at 1 year was 44%. There were 4 miscarriages and there are 3 ongoing pregnancies. The live delivery rate was 36%. Assuming a 29% delivery rate for microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection, the cost per newborn was $51,024, compared to $31,099 for vasoepididymostomy. CONCLUSIONS: Vasoepididymostomy is more successful and more cost-effective than microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection for vasectomy reversal. It does not expose the women to complications in the treatment of a male problem and it is indicated for treatment of epididymal obstruction secondary to vasectomy. Microsurgical epididymal sperm aspiration and intracytoplasmic sperm injection should be reserved for cases not amenable to surgical reconstruction.

Cytoplasm↗

PubMed1997

Neonatal conditioning for adult respiratory behavior.

Specific challenges and perturbations presented during certain 'sensitive periods' of neonatal life have been shown to modify the structure and function of several physiological systems in such as way as to produce long-term and often permanent changes in the behavioral expression of the system. These same phenomena have been reported in a few studies of respiratory control. We have shown that a conditioning paradigm of intermittent sleep interruption presented during the first 4 weeks of life in rats will increase the number of respiratory pauses (apneas > 1 sec in duration) observed in these animals some 10-12 weeks later. Furthermore, in adult conditioned animals, apneic pauses can be dramatically reduced by a counter-conditioning stimulus (white noise), and abolished completely by barbiturate anesthesia. These observations indicate that the respiratory control system in the brainstem of the neonate contains a degree of developmental plasticity which is experience-dependent and modifiable, and that the adult expression of acquired apneic breathing patterns can be effectively reduced by behavioral methods.

Animals↗

PubMed1997

Ventilation and metabolism among rat strains.

We examined ventilation and metabolism in four rat strains with variation in traits for body weight and/or blood pressure regulation. Sprague-Dawley [SD; 8 males (M), 8 females (F)], Brown Norway (BN; 10 M, 11 F), and Zucker (Z; 11 M, 12 F) rats were compared with Koletsky (K; 11 M, 11 F) rats. With the use of noninvasive plethysmography, frequency, tidal volume, minute ventilation (VE), O2 consumption, and CO2 production were derived at rest during normoxia (room air) and during the 5th minute of exposure to each of the following: hyperoxia (100% O2), hypoxia (10% O2-balance N2), and hypercapnia (7% CO2-balance O2). Statistical methods probed for strain and sex effects, with covariant analysis by body weight, length, and body mass. During resting breathing, strain effects were found with respect to both frequency (BN, Z > K, SD) and tidal volume (SD > BN, Z) but not to VE. Sex influenced frequency (F > M) alone. Z rats had higher values for O2 consumption, CO2 production, and respiratory quotient than the other three strains, with no independent effect by sex. During hyperoxia, frequency was greater in BN and Z than in SD or K rats; SD rats had a larger tidal volume than BN or Z rats; Z rats had a greater VE than K rats; and M had a larger tidal volume than F. Strain differences persisted during hypercapnia, with Z rats exhibiting the highest frequency and VE values. During hypoxic exposure, strain effects were found to influence VE (SD > K, Z), frequency (BN > K), and tidal volume (SD > BN, K, Z). Body mass was only a modest predictor of VE during normoxia, of both VE and tidal volume with hypoxia, hypercapnia, or hyperoxia, and of frequency during hypercapnia. We conclude that strain of rats, more than their body mass or sex, has major and different influences on metabolism, the pattern and level of ventilation during air breathing, and ventilation during acute exposure to hypercapnia or hypoxia.

Animals↗

PubMed1997

Cardiovascular and metabolic responses to electrical stimulation-induced leg exercise in spinal cord injury.

Electrical stimulation-induced leg muscle contractions provide a useful model for examining the role of leg muscle neural afferents during low-intensity exercise in persons with spinal cord-injury and their able-bodied cohorts. Eight persons with paraplegia (SCI) and 8 non-disabled subjects (CONTROL) performed passive knee flexion/extension (PAS), electrical stimulation-induced knee flexion/extension (ES) and voluntary knee flexion/extension (VOL) on an isokinetic dynamometer. In CONTROLs, exercise heart rate was significantly increased during ES (94 +/- 6 bpm) and VOL (85 +/- 4 bpm) over PAS (69 +/- 4 bpm), but no changes were observed in SCI individuals. Stroke volume was significantly augmented in SCI during ES (59 +/- 5 ml) compared to PAS (46 +/- 4 ml). The results of this study suggest that, in able-bodied humans, Group III and IV leg muscle afferents contribute to increased cardiac output during exercise primarily via augmented heart rate. In contrast, SCI achieve raised cardiac output during ES leg exercise via increased venous return in the absence of any change in heart rate.

Electric Stimulation↗

PubMed1996

Sonographic estimation of fetal body composition with gestational diabetes mellitus at term.

OBJECTIVE: To derive models and equations for estimating fetal lean mass and fat mass in women with gestational diabetes mellitus (GDM), using sonographic techniques and neonatal total body electrical conductivity. METHODS: Twenty women with GDM at term underwent sonographic evaluation within 72 hours before delivery. Sonographic studies included measurements of the fetal biparietal diameter, head circumference, abdominal circumference, anterior and lateral abdominal-wall subcutaneous fat thicknesses, femur length, mid-thigh circumference, and anterior and lateral thigh subcutaneous fat thicknesses. Within 24 hours of birth, the infants were weighed and their body composition estimated with total body electrical conductivity measurements. Volume-based models and regression equations for estimating lean and fat mass were derived. The equations were validated prospectively in the next 16 women with GDM. RESULTS: There were no significant differences in maternal or neonatal demographic or anthropometric data between the derivative and validation groups. The equation for estimating fetal lean mass is: lean mass = 0.169(volume of head) + 0.262(volume of lean trunk) - 308.59 (r = 0.86, P < .01). The equation for estimating fetal fat mass is: fat mass = 0.241(volume of fat sheath of trunk) - 213.13 (r = 0.73, P < .01). In the validation group, the sonographic estimates of fetal lean and fat mass were not significantly different than those estimated by total body electrical conductivity (P = .18 and P = .77, respectively). CONCLUSION: Fetal body composition can be estimated by obtaining several additional measurements during routine fetal sonography.

Body Composition↗

PubMed1996

Preferences for intracytoplasmic sperm injection versus donor insemination in severe male factor infertility: a preliminary report.

With the advent of intracytoplasmic sperm injection (ICSI), our programme noted a drop in the number of couples using donor insemination (DI) for severe male factor infertility. Over the first 8 months in which our infertility programme offered both treatments, 27 consecutive couples scheduled for ICSI and 15 consecutive couples scheduled for DI were evaluated Since all patients in our infertility programme beginning in-vitro fertilization (IVF) with planned ICSI or starting DI undergo a semi-structured psychological interview, the psychologist's clinical notes as well as the medical chart were reviewed and coded retrospectively to determine factors related to a couple's treatment choice. Couples who chose IVF-ICSI over DI had a higher occupational status and included husbands with higher educational levels. Their most common motivation was to have the husband's biological child (93% of couples in the ICSI group). The most common motivation for choosing DI (60% of DI couples) was that IVF was not financially affordable. Choice of treatment was not related to psychological adjustment, the husband having prior biological children, or his risk of passing on a genetic defect to offspring. These preliminary data raise the concern that, with the success of ICSI, DI may change in the USA from being an option dictated by semen quality to a second choice treatment utilized for economic reasons.

Adult↗

PubMed1996

Acute spermatic cord torsion alters the microcirculation of the contralateral testis.

PURPOSE: The purpose of this study was to characterize the hemodynamic changes in the contralateral testis during acute spermatic cord torsion in anesthetized rats. MATERIALS AND METHODS: We used videomicroscopy to examine the microcirculation of the contralateral testis following acute torsion. Specifically, we examined the effect on vasomotion, a rhythmic dilation and constriction of the arterioles that is involved in fluid and nutrient exchange and modulation of local vascular resistance. In a separate set of experiments, blood flow in the contralateral internal spermatic artery was measured with an ultrasonic flow probe during acute torsion. RESULTS: Following 720 degrees torsion, the amplitude of vasomotion in the contralateral testis increased 121% (29.0 +/- 3.9% versus 13.0 +/- 1.7%) compared with controls. Blood flow in the contralateral internal spermatic artery decreased 43% after 2 hours' torsion. CONCLUSIONS: Acute spermatic cord torsion altered the microcirculation by increasing the amplitude of vasomotion and decreased total blood flow to the opposite testis. Because the hydraulic resistance of a blood vessel exhibiting vasomotion is always less than a vessel with the same average but static diameter, the observed microcirculatory changes may be an adaptive response to preserve local flow in the presence of decreased total flow. The long-term consequences of these changes in the microcirculation may affect testicular function and ultimately fertility.

Acute Disease↗

PubMed1996

Optimal dose and duration of exposure to artificial stimulants in cryopreserved human spermatozoa.

PURPOSE: Poor sperm motility after cryopreservation is associated with infertility. For any pharmacological stimulation to be of clinical value, its effect in enhancing motility and other motion characteristics should be maintained for at least 1 hour. MATERIALS AND METHODS: Three motility stimulants (pentoxifylline, caffeine and 2-deoxyadenosine) were incubated with post-thaw semen samples from 11 healthy donors for 0, 30, 60, 120 and 180 minutes. The final concentrations used were 2.5 mM., 5 mM. and 10 mM. for pentoxifylline; 1 mM., 2 mM. and 5 mM. for caffeine, and 0.5 mM., 1 mM. and 2.5 mM. for 2-deoxyadenosine. Percent motility and changes in motion characteristics were measured on a computer assisted semen analyzer. RESULTS: Compared to controls (0 minutes, no stimulant), an immediate increase in motility and other motion parameters was noted with all 3 stimulants. All stimulants caused a significant increase in percentage motility at all periods studied (p < 0.01). Similarly, pentoxifylline increased other motion parameters at the 2.5 mM. concentration (p < 0.01), caffeine was effective in increasing curvilinear velocity, average path velocity and amplitude of lateral head displacement (p < 0.01) at 5 mM., and 1 and 2.5 mM. of 2-deoxyadenosine increased the curvilinear velocity, straight line velocity, average path velocity and amplitude of lateral head displacement (p < 0.01). Among all stimulants only 2-deoxyadenosine increased linearity only at the 1 mM. concentration. CONCLUSIONS: Our study suggests that these stimulants, when used at optimum concentrations, can maintain the improved sperm quality for durations longer than the minimum needed for fertilization. This finding may be significant in improving the poor semen quality observed after cryopreservation in oligospermic samples and in semen specimens from cancer patients.

Caffeine↗

PubMed1996

Value of clinical diagnosis in predicting the quality of cryopreserved sperm from cancer patients.

PURPOSE: Cryopreservation of semen from patients with malignant diseases (primarily testicular cancer, Hodgkin's disease and lymphoma) before specific chemotherapy, radiation or surgical therapy has become a realistic option to preserve fertility. Nevertheless, the post-thaw sperm quality in these patients is poor. Whether the clinical diagnosis of malignancy affects the cryopreservation of human sperm is unknown. Such an association could allow post-thaw sperm quality to be predicted. MATERIALS AND METHODS: We compared the effect of cryopreservation on sperm motility, velocity, linearity, amplitude of lateral head movement, motility index and motile sperm count in specimens from 30 normal men, 34 with testicular cancer, 39 with Hodgkin's disease, and 19 with leukemia and lymphoma who were referred for sperm banking during a 5-year period. RESULTS: The pre-freeze and post-thaw motility, motility index and motile sperm count were significantly lower in patients than in normal men (p < 0.01). No significant differences were noted among the patient groups. Similarly, no significant differences were noted after cryopreservation. Our results indicate that the poor pre-freeze sperm quality in some patients with malignancies explains the poor post-thaw results. However, the deterioration in sperm function after cryopreservation of semen among patients with different malignancies and normal donors appears to be similar. CONCLUSIONS: Clinical diagnosis of malignancy is not an adequate predictor of the effect of cryopreservation on human semen.

Cryopreservation↗

PubMed1996

Suitability of the hypo-osmotic swelling test for assessing the viability of cryopreserved sperm.

OBJECTIVE: To determine whether the hypo-osmotic swelling test can assess viability of frozen spermatozoa. DESIGN: Fresh semen specimens were divided into two aliquots: one was not processed and the other was processed by swim-up. Both aliquots were then cryopreserved by the liquid nitrogen vapor method. SETTING: Andrology laboratory at a tertiary care facility. PATIENT(S): Eleven volunteers with proven fertility. INTERVENTION(S): The hypo-osmotic swelling test and the sperm viability assessment by Hoechst 33258 (Sigma Chemical Co., St. Louis, MO) and eosin-nigrosin strains were performed in each aliquot. MAIN OUTCOME MEASURE(S): The results of hypo-osmotic swelling test as indicated by swelling of sperm tails were compared with the viability results obtained by Hoechst 33258 stain before freezing and by Hoechst-33258 and eosin-nigrosin stains after freezing. RESULT(S): The hypo-osmotic swelling test and Hoechst 33258 viability results were correlated highly in unprocessed and processed fresh specimens (r = 0.95). After cryopreservation, there was no correlation between hypo-osmotic swelling test and Hoechst 33258 or between hypo-osmotic swelling test and eosin-nigrosin. Prefreeze sperm processing did not influence the post-thaw results. Viability assessed by Hoechst 33258 and eosin-nigrosin was well correlated (r = 0.72). CONCLUSION(S): The hypo-osmotic swelling test can accurately evaluate viability in fresh human spermatozoa but not in cryopreserved ones. Thus, this test cannot be used to select viable cells in cryopreserved samples for assisted reproductive procedures, such as intracytoplasmic sperm injection.

Aniline Compounds↗

PubMed1995

Cryopreservation and semen quality in patients with Hodgkin's disease.

BACKGROUND: Cryopreservation of semen from patients with Hodgkin's disease yields fewer motile sperm than from fertile men without Hodgkin's disease. However, although poor sperm quality and subfertility have been associated with Hodgkin's disease, whether the disease adversely affects sperm quality is not clear because many studies evaluated semen quality after chemotherapy or radiation therapy had begun. Furthermore, the effect of cryopreservation on semen quality in these patients is unknown. This study investigated pretreatment sperm quality and the effect of cryopreservation on semen quality in patients with Hodgkin's disease. METHODS: Specimens from 39 patients with Hodgkin's disease and 30 normal volunteers who underwent sperm banking over a 5-year period were analyzed. No patient had undergone chemotherapy or radiation therapy before sperm banking. The nitrogen vapor technique, using Test-Yolk buffer with glycerol as a cryoprotective agent, was used for cryopreservation. Prefreeze and postthaw motile sperm count (MSC) and motion characteristics, namely motility, curvilinear velocity (VCL), linearity, amplitude of lateral head movement (ALH), and motility index, were compared between the two groups. RESULTS: Prefreeze values for MSC (P = 0.0001), motility (P = 0.0001), motility index (P = 0.0001), and VCL (P = 0.0019) differed significantly between patients and donors. Except for linearity and ALH, postthaw sperm MSC, motility, VCL, and motility index decreased significantly (P = 0.0001) in both groups. However, the percentage decline in semen quality from prefreeze to postthaw values did not differ significantly between donors and patients. CONCLUSION: The pretreatment semen quality in patients with Hodgkin's disease is poor compared with that of normal fertile men. However, half the patients had a normal MSC, so a clinical diagnosis of Hodgkin's disease does not predict cryopreservation outcome adequately. Semen cryopreservation should be encouraged as a routine part of the therapeutic management of men of reproductive age who will undergo chemotherapy or radiation therapy for Hodgkin's disease.

Adolescent↗

PubMed1995

Positive myeloperoxidase staining (Endtz test) as an indicator of excessive reactive oxygen species formation in semen.

PURPOSE: Although the significance of leukocytospermia in semen remains controversial, evidence exists that white blood cells (WBCs) may adversely affect sperm function and act as a potential cofactor in male infertility. Nevertheless, the mechanisms by which leukocytes may alter sperm function in vitro is unknown. Recent investigations suggest that reactive oxygen species (ROS) generated by the polymorphonuclear (PMN) granulocytes could adversely affect sperm function. The objective of this study was to investigate the relationship between the presence of leukocytospermia as determined by the Endtz test and the excessive formation of ROS. METHODS: The WBC concentration and ROS formation in human semen, obtained from men consulting for infertility, were assessed and compared to that of normal donors. ROS was measured by a chemiluminescence assay using luminol and a Berthold luminometer. The WBC concentration was determined with a myeloperoxidase staining technique (Endtz test). Specimens were obtained from 94 subjects (20 donors, 74 patients). RESULTS: Of the 20 donors, 2 were Endtz positive and ROS positive; 18 were Endtz negative with 2 (11%) ROS positive. In the patient group (n = 74), 26 (35%) were ROS positive, and 17 were Endtz positive and found to be ROS positive. Of the 57 Endtz-negative patients, 9 (15%) were ROS positive. The positive Endtz test results correlated strongly with positive ROS formation in patients and donors (P < 0.001). CONCLUSIONS: Our results indicate that the simple, cost-efficient Endtz test could be used as an indicator of excessive ROS formation in semen.

Humans↗

PubMed1995

Anthropometric estimation of neonatal body composition.

OBJECTIVE: Estimation of neonatal body composition can be useful in the understanding of fetal growth. However, body composition methods such as total body water and total body electric conductivity are expensive and not readily available. Our primary purpose was to develop an anthropometric model to estimate neonatal body composition and prospectively validate the model against total body electric conductivity and secondarily to compare our anthropometric model and a previously published anthropometric formula with total body electric conductivity. STUDY DESIGN: A total of 194 neonates had estimates of body composition according to total body electric conductivity (group 1). Parental morphometrics, gestational age, race, sex, parity, and neonatal measurements including birth weight, length, head circumference, and skinfolds (triceps, subscapular, flank, and thigh) were correlated with body fat by use of stepwise regression analysis. The model was validated in a second group of 65 neonates (group 2). RESULTS: There were no significant differences in any of the parental or neonatal measurements between groups 1 and 2. In group 1, 78% of the variance in body fat with the use of total body electric conductivity was explained by birth weight, length, and flank skinfold (R2 = 0.78, p = 0.0001). When prospectively validated by the subjects in group 2, the model had significant and stronger correlation (R2 = 0.84, p = 0.0001) with body fat estimated by total body electric conductivity as compared with the other anthropometric model (R2 = 0.54, p = 0.0001). There was no significant (p = 0.11) difference between our anthropometric estimate of body fat and total body electric conductivity. CONCLUSIONS: The anthropometric model developed can be used to reasonably predict neonatal body fat mass at birth.

Adipose Tissue↗

PubMed1995

Mutations of aspartate 103 in the Hm2 receptor and alterations in receptor binding properties of muscarinic agonists.

Aspartate 103 (D103) in the third transmembrane domain of the Hm2 receptor was mutated to glutamate (D103E), asparagine (D103N), or alanine (D103A). As measured by [3H]-NMS, no significant binding was observed in D103A, while a 2-fold decrease in ligand affinity was seen in D103E and a 32-fold decrease in affinity was found in the D103N mutant. Examination of reference agonists showed greater loss of affinity in D103N than in D103E with the rank order of change being: L-607,207>carbachol>arecoline>pilocarpine>oxotremorine>McN-A-343. Of the novel 1-azabicyclo[2.2.1]-heptan-3-one oxime agonists examined, arylacetylene oximes showed little alteration in binding in either the D103E or D103N mutants, while the geometric isomers of several bicyclic aryl-ene-yne oximes showed significant changes in affinity, especially in the D103N mutant. Thus, overall size of the agonist and/or spatial orientation of the molecule within the binding pocket contribute to changes measured in binding.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗