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Biomedical subjects

D W Warren

Publications and source records attributed to D W Warren.

At least 109 records · Page 6Linked to original sources
PubMed1989

Screening of velopharyngeal inadequacy by differential pressure measurements.

Warren (1979) described an approach for screening velopharyngeal inadequacy using a device (PERCI) that measures orifice differential pressure (P). The PERCI score is based on the relationship between velopharyngeal orifice (VPO) area and velopharyngeal orifice differential pressure. The purpose of this study was to test the original assumptions, which were based on modeling experiments and a small sample size. The sample in this study included 515 subjects who demonstrated various degrees of velopharyngeal inadequacy. The pressure-flow technique was used to estimate velopharyngeal orifice size and to measure orifice differential pressure. The data demonstrate that differential pressures greater than 3.0 cm H2O generally predict adequacy of closure, whereas differential pressures less than 3.0 cm H2O usually indicate inadequacy. These findings support the use of orifice differential pressure as a simple screening of velopharyngeal function.

Humans↗
PubMed1989

Dimensions of the cleft nasal airway in adults: a comparison with subjects without cleft.

The prevalence of mouthbreathing among individuals with cleft lip and palate is significantly higher than in the normal population. This has been attributed to nasal deformities that tend to reduce nasal airway size. The purpose of the present study was to determine how a heterogeneous adult group with cleft lip and palate differs in terms of nasal airway cross-sectional area from an adult group without cleft during the inspiratory and expiratory phases of breathing. The pressure-flow technique was used to estimate nasal airway size in 15 adults without cleft (15 years or older) and 37 adults with cleft lip, cleft palate, or both. Mean areas and standard deviations for subjects without cleft were 0.63 cm2 +/- 0.17 during inspiration and 0.56 cm2 +/- 0.14 during expiration. This difference is statistically significant (p less than 0.01). Mean areas and standard deviations for all subjects with cleft were 0.37 cm2 +/- 0.18 during inspiration and 0.40 cm2 +/- 0.20 during expiration. This difference is not statistically significant (p greater than 0.15). Twenty-two of the subjects with cleft had nasal areas considered to be impaired (below 0.40 cm2) as compared with only three of the subjects without cleft. A two factor analysis of variance (ANOVA) demonstrated that area changes during respiration are different for subjects with and without cleft (p less than 0.005), and that cleft nasal areas are smaller than noncleft areas for both phases of breathing (p less than 0.001). Inspiratory-expiratory differences between subjects with and without cleft are probably the result of developmental defects, reparative surgery or both.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Effects of cleft lip and palate on the nasal airway in children.

Clefts of the lip and palate often produce significant nasal deformities and reduced nasal airway size. The purpose of this study was to assess how type of cleft affects nasal cross-sectional area and mode of breathing. The pressure-flow technique was used to estimate nasal airway size and modified inductive plethysmography was used to determine percent of nasal breathing in 60 children with cleft lip and palate aged 6 to 15 years. Ninety-five normal children served as controls. The data demonstrate that nasal size decreased among cleft types as follows: children with bilateral cleft lip and palate had largest airway, followed by unilateral cleft lip, cleft of the hard and soft palate, cleft of the soft palate, and unilateral cleft lip and palate. The data also indicated that most subjects with cleft were mouth breathers. Results of otolaryngologic examinations suggest that septal deformities affecting nasal valve function are responsible for much of the impairment, especially in the group with unilateral cleft lip and palate. The differences among groups appear to relate to developmental differences associated with the original defect and the surgical procedures used in primary repair.

Adolescent↗
PubMed1988

Morphological and biochemical changes in the adult male rat reproductive system following long-term treatment with 1,2-dibromo-3-chloropropane.

Adult Long-Evans male rats were treated with various dosages of pure or technical grade 1,2-dibromo-3-chloropropane (DBCP), epichlorohydrin (Epi), or allyl chloride (AC) for 1, 3, or 6 months on a daily basis. AC, which is the substrate for the production of DBCP, and Epi, which is a contaminant and/or metabolite of DBCP, had no effect on any of the parameters of the male reproductive system studied. The deleterious effects on male reproduction are therefore attributable specifically to DBCP. The effects of DBCP were dose and duration dependent. At the lowest dose (1 mg/kg) DBCP did not have any discernible effects on the male reproductive system. By 3 months of treatment at the intermediate dose of 5 mg/kg, the morphology of the testis ranged from normally appearing seminiferous tubules to ones which contained Sertoli cells only. At 6 months of treatment there was a reduction in the weights of the testes and sexual accessory glands. At the highest dose, the majority of the rats showed advanced testicular regression by 1 month of treatment. The most extreme testicular regression was observed in the 6-month treatment group. Almost all of the seminiferous tubules of all of the rats were composed of Sertoli cells only. In some of the animals, a few isolated seminiferous tubules contained an occasional spermatogonium or primary spermatocyte. Some of the Leydig cells of the rats in this group showed morphological evidence of atrophy as evidenced by the clumping of chromatin and paucity of stainable cytoplasm. This was confirmed by lower levels of intratesticular testosterone, a significant reduction in the number of luteinizing hormone (LH) receptors and increased serum levels of LH and follicle-stimulating hormone (FSH). From these results we conclude that DBCP is a specific male gonadotoxin and that the effects are not a result of contamination or metabolism. The effects appear to be a direct action at the testicular level because feedback inhibition to the pituitary gland was adversely affected.

Animals↗
PubMed1988

Alterations in nasal respiration and nasal airway size following superior repositioning of the maxilla.

Twenty patients who underwent superior repositioning of the maxilla via Le Fort I down fracture had their respiratory mode and nasal cross-sectional area determined prior to and 6 months following surgery. Inductive plethysmography and nasal air flow techniques were used in the determination of these parameters. Prior to surgery, five patients were nasal breathers, five were predominantly nasal breathers, six were oral-nasal breathers, and four were predominantly oral breathers. Nine patients had inadequate nasal airways. Six months following surgery, 14 patients were nasal breathers and six were predominantly nasal breathers. Sixteen patients had adequate nasal airways, three had borderline nasal airways and one had an inadequate nasal airway postsurgically. These findings suggest that superior repositioning of the maxilla by Le Fort I down fracture does not adversely affect nasal respiration. Nasal function actually improved in 17 of the 20 subjects studied.

Adolescent↗
PubMed1988

The relationship between nasal airway size and nasal-oral breathing.

Most clinicians agree that impaired nasal breathing results in obligatory mouth breathing. Some believe that mouth breathing influences dentofacial growth; others disagree. The term mouth breathing is confusing because total mouth breathing rarely occurs. A combination of nasal and oral breathing is more usual. The purpose of the present study involving 116 adult subjects was to (1) assess the relationship between nasal impairment and nasal-oral breathing, (2) determine the switching range from nasal to nasal-oral breathing, and (3) quantify the term mouth breathing. The pressure-flow technique was used to estimate nasal airway size; inductive plethysmography was used to assess nasal-oral breathing in normal and impaired breathers. Analysis of the date showed a Pearson rank correlation of 0.545 (P less than 0.001) between nasal area and nasal-oral respiration. Ninety-seven percent of subjects with a nasal size less than 0.4 cm2 were mouth breathers to some extent. About 12% of subjects with an adequate airway were assumed to be habitual mouth breathers. The findings indicate that the switching range from nasal to nasal-oral breathing is very narrow (0.4-0.45 cm2). These results also confirm our contention that in adults an airway less than 0.4 cm2 is impaired.

Adult↗
PubMed1988

Intraoral pressure, nasal pressure and airflow rate in cleft palate speech.

We have suggested that compensatory behaviors associated with cleft palate may be strategies developed for the purpose of satisfying the requirements of a speech regulating system. The purpose of the present study was to test this hypothesis in subjects demonstrating various degrees of velopharyngeal inadequancy. The pressure-flow technique was used to assess aerodynamic responses to a loss of velar resistance in 74 subjects compared to a control group of 137 subjects with adequate velopharyngeal closure. The results of this study demonstrate that as degree of inadequacy increased, airflow rate also increased. Although intraoral pressure fell as inadequacy increased, many subjects were able to maintain pressures above 3.0 cm H2O by increasing airflow rate. Nasal pressure increased in proportion to the decrease in intraoral pressure while combined nasal plus oral pressure remained constant across groups. These findings suggest that a loss of resistance at the velar port is compensated by an increase in resistance at the nasal port. Airflow rate appears to be adjusted to total upper airway resistance. These findings support our contention that the speech system is constrained to meet aerodynamic requirements.

Adolescent↗
PubMed1988

An industrial hygiene appraisal of triethylamine and dimethylethylamine exposure limits in the foundry industry.

For nearly two decades, triethylamine and dimethylethylamine have been used as catalysts for phenolic urethane cold box binders in the foundry industry. During that time there have been reports of employees experiencing visual disturbances as a result of exposure to these amines. Some of these accounts have reported visual disturbances occurring at exposure levels below present limits. This study was conducted to define visual effects experienced by employees and to determine ambient concentrations at which effects were occurring. Study results suggest that present exposure limits may not be adequate to prevent the occurrence of visual disturbances. Suggested exposure guidelines have been developed which, it is believed, will prevent the occurrence of these unwanted effects.

Environmental Exposure↗
PubMed1988

The effects of fetal exposure to 1,2-dibromo-3-chloropropane on adult male reproductive function.

Several drugs have been shown to cross the placental barrier and affect the fetal testis causing a reduction in testosterone with a resultant impairment of sexual differentiation and an ultimate problem in adult sexual function. In this study, pregnant female rats were treated with 25 mg/kg of the pesticide 1,2-dibromo-3-chloropropane (DBCP). Treatment began on Days 14.5, 16.5, or 18.5 and continued through Day 19.5 of gestation. Some animals were killed on Day 20.5 of intrauterine life and fetal intratesticular testosterone was measured. All other animals were allowed to deliver, and the males were raised to adulthood. At adulthood, body, testis, prostate glands and seminal vesicle weights were recorded. Intratesticular testosterone and luteinizing hormone (LH) receptors were measured. Male and female sexual behavior was quantified and the volume of the sexually dimorphic nucleus of the preoptic area of the hypothalamus was calculated. The histological appearance of the testis was also examined. Treatment for 6 days during fetal life with DBCP decreased intratesticular testosterone by 50% compared to controls at 20.5 days of gestation. At adulthood, all male rats treated during fetal life had a reduced body weight that was correlated with the duration of exposure. Adult testis weight was reduced to 75% of controls as a result of 2 days of fetal exposure to DBCP, whereas 4 and 6 days of exposure during fetal life reduced testis weight by greater than 90%. LH receptors and intratesticular testosterone, in the adults treated during fetal life, were also dramatically reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Maintenance of intraoral pressure during speech after maxillary resection.

Although structural defects such as cleft palate and severe anterior open bite alter vocal tract resistance, compensatory responses usually result in maintaining consonant pressures at an adequate level. The purpose of the present study was to determine if individuals with an acquired palatal defect spontaneously develop similar compensatory behaviors. The pressure-flow technique was used to measure aerodynamic variables associated with consonant production after surgery and obturation. Although intraoral pressures decreased considerably immediately after surgery, pressures were maintained at a mean level of 3.5-cm H2O. Respiratory volumes increased as much as fourfold without obturation and were normal with obturation. Voice-voiceless differences in air volumes among consonants were maintained even in the presence of the defect. These findings suggest that compensatory responses are directed toward maintaining an appropriate level of intraoral pressure for consonant production.

Adult↗
PubMed1988

Prevalence of mouthbreathing in cleft lip and palate.

The purpose of the present study was to determine the prevalence of mouthbreathing in the cleft population. Percent nasal breathing was assessed in 85 children and adults using a pneumotachograph to measure nasal volumes and an inductive plethysmograph to measure tidal volumes. Breathing mode was defined using the following classifications of percent nasal breathing: 80 to 100 percent, nasal; 60 to 79 percent, predominantly nasal; 40 to 59 percent, mixed oral-nasal; 20 to 39 percent, predominantly oral; 0 to 19 percent, oral. Results demonstrate that 68 percent of the subjects were oral, predominantly oral or mixed oral-nasal breathers, and 32 percent were predominantly nasal or nasal breathers. Adults had the same prevalence of mouthbreathing as children. These findings demonstrate that cleft lip/palate and its treatment frequently compromise nasal respiration.

Adolescent↗
PubMed1988

Intraoral pressure and its relationship to velopharyngeal inadequacy.

Intraoral pressure measurements were made during multiple productions of the word "hamper" by each of 267 patients who manifested differing degrees of velopharyngeal inadequacy. The results indicate that intraoral pressure diminishes as the extent of velopharyngeal impairment increases. However, pressure remained above 3 cm H2O in the majority of subjects, even when the impairment was such that intraoral and intranasal pressures were essentially equal. Comparison of these results with model simulations suggests that speakers make adjustments to velopharyngeal impairment that tend to maintain pressures at levels thought to be necessary for obstruent consonant production. Variations in pressure as a function of gender and age parallel those observed in normal children and adults.

Adolescent↗
PubMed1988

Screening of velopharyngeal closure based on nasal airflow rate measurements.

Although sophisticated techniques for estimating velopharyngeal port area during speech are available, clinicians continue to seek approaches for screening patients with suspected velar inadequacy. The aim of the present study is to determine the sensitivity and specificity of predicting velopharyngeal dysfunction based on nasal airflow measurements. The pressure-flow technique was used to measure velopharyngeal orifice area and nasal airflow rate in 211 subjects with cleft palate or velar dysfunction, or both. The data demonstrate that nasal airflow rates above 125 cc/sec are almost always associated with velar dysfunction. Sensitivity and specificity of this index were high (0.85 and 0.96, respectively). A correct diagnosis was made in 93% of the cases. As expected, errors in judgment occurred most frequently in subjects with borderline velopharyngeal inadequacy.

Adolescent↗
PubMed1987

Effects of size of the nasal airway on nasal airflow rate.

The controversy concerning the effects of nasal airway impairment on facial growth has stimulated renewed interest in upper airway respiratory function. We assessed the relationship between nasal airway patency and nasal airflow rate, using the pressure-flow technique to estimate nasal cross-sectional size and nasal airflow rate in 30 normal and 82 nasally impaired adults. Groups were categorized according to otolaryngologic examination results and pressure-flow measurements. The results clearly demonstrate that size of the airway influences airflow rate when the smallest nasal cross-sectional area is under 0.4 cm2. The data suggest that the nose becomes flow-limiting when it is less than 0.18 cm2. These data support our contention that nasal airway impairment in adults occurs when the airway is less than 0.4 cm2 in size.

Adult↗
PubMed1987

Physiologic responses to maxillary resection and subsequent obturation.

Aerodynamic assessment of prosthetic obturation provides the clinician with important information on adequacy of the seal between the oral and nasal cavities. The technique is easy to apply and provides quantitative data on effectiveness of obturation. In addition, the pressure-flow technique provides important information on how individuals respond to changes in the integrity of oral and pharyngeal structures. This study demonstrates that individuals with large surgical defects increase respiratory effort during nonnasal consonant productions in order to maintain adequate intraoral speech pressures. Successful obturation of the defect maintains the speech pressures while dramatically reducing respiratory effort.

Adult↗
PubMed1987

Reproductive defects in the male diabetic athymic nude mouse.

We have previously reported spontaneous hyperglycemia and impaired glucose tolerance in male athymic nude Balb/c mice. This colony also demonstrates impaired fertility. Previous studies in both athymic nude and diabetic obese (ob/ob) mice have shown reproductive abnormalities. It was the purpose of this investigation to further elucidate the endocrine abnormalities which might contribute to the reduced fertility observed in this model. Fasting plasma glucose was measured on each nude mouse to ensure that a diabetic state existed. Testes were removed and intratesticular testosterone and LH receptors were measured. Testosterone levels in diabetic, athymic nude Balb/c (DAN) mice were significantly decreased to 46.5% of control Balb/c mice. LH receptors in DAN mice were significantly elevated by 23.6% when compared to control animals. These results demonstrate that the impaired fertility observed in the DAN mouse may result from decreased testosterone production. The increased LH receptor levels seen in the DAN mouse might reflect a regulatory event in response to the decreased intratesticular testosterone levels.

Animals↗