Biomedical subjects

J Sundberg

Publications and source records attributed to J Sundberg.

At least 37 records · Page 2Linked to original sources

PubMed1998

Kinetics of methylmercury and inorganic mercury in lactating and nonlactating mice.

The elimination of mercury was followed for 9 days (Days 10-19 of lactation) in milk and/or 21 days in blood and plasma of lactating and nonlactating mice administered a single iv injection of either 203Hg-labeled methylmercuric chloride or 203Hg-labeled mercuric chloride (0.5 mg Hg/kg body wt). Demethylation of methylmercury to inorganic mercury was taken into consideration by analyzing the data with a combined pharmacokinetic model based on the assumption of constant blood plasma ratios for methylmercury and inorganic mercury. A three-compartment model fitted the blood and plasma concentrations vs time profiles for both compounds. Plasma clearance and volume of distribution at steady state for methylmercury were 95. 3 ml/h/kg and 18,500 ml/kg, respectively, in lactating mice, and significantly higher than in nonlactating mice with values of 47.1 ml/h/kg and 9400 ml/kg, respectively. The terminal half-lives of methylmercury in plasma were similar, 170 h in lactating and 158 h in nonlactating mice. No differences were observed between the pharmacokinetic parameters in lactating and nonlactating mice administered inorganic mercury. The lactational transfer of mercury was more efficient following administration of inorganic mercury than after administration of methylmercury, with a five times higher peak concentration in milk, higher milk:plasma concentration ratios, and 8% of the administered dose excreted in milk compared with 4% for methylmercury. Mercury concentrations in milk following an iv dose of inorganic mercury decreased with a terminal half-life of 107 h, whereas after administration of methylmercury, the concentration of total mercury in milk remained at an almost constant level during the whole period of investigation. There was a nonlinear relationship between mercury in milk and plasma following inorganic mercury administration. It is suggested that inorganic mercury enters the mammary gland by a carrier-mediated transport system, which is saturated at high plasma levels of inorganic mercury. The present study shows that physiological changes during lactation alter the pharmacokinetics for methylmercury in mice but not for inorganic mercury.

Animals↗

PubMed1998

Effects of lung volume on vertical larynx position during phonation.

The vertical position of the larynx seems to be relevant to voice function. As a high vertical larynx position is often seen in hyperfunctional and strained voices, a lowering of a habitually elevated larynx is sometimes a specific goal in clinical voice therapy and different larynx-lowering exercises are used to achieve this goal. Earlier investigations have shown that pitch and to some extent also vocal loudness are relevant to vertical larynx position. In the present investigation, we examine if lung volume affects vertical larynx position. Using a multi-channel electroglottograph, the larynx position was measured in 29 healthy, vocally untrained subjects, who phonated at different lung volumes, pitches, and degrees of vocal loudness. The main results were that high lung volume was clearly associated with a lower larynx position as compared to low lung volume. In addition, vertical larynx position was strongly correlated with pitch. Both of these dependencies were shown to be stronger in males than in females. Our results suggest that lung volume is a factor that is highly relevant to larynx height in untrained subjects.

Adult↗

PubMed1998

Data on subglottal pressure and SPL at varied vocal loudness and pitch in 8- to 11-year-old children.

Phonation threshold pressure has been defined as the minimum subglottal pressure to generate phonation. Previous research has indicated that children may habitually employ higher subglottal pressures than adults. In the present investigation sound pressure level (SPL) and subglottal pressures at different pitch levels were measured at and above phonation threshold in nine children. Phonation threshold values were scattered in reasonable agreement with Titzes' prediction, although a discrepancy was noted regarding the frequency dependence in some voices. At normal conversational loudness and loudest level of phonation the children's Ps values were between two to four and four to eight times the predicted threshold values, respectively. At normal conversational loudness and habitual pitch subglottal pressures were lower than those previously observed for children, but similar to those found for female adults. The SPL in softest and loudest phonation were somewhat lower as compared to previous phonetogram data for children and for female adults. At normal loudness and habitual pitch the SPL values were similar to those of female adults. For a doubling of Ps mean SPL increased by 10.5 dB on the average.

Child↗

PubMed1998

Effects of lung volume on the glottal voice source.

According to experience in voice therapy and singing pedagogy, breathing habits can be used to modify phonation, although this relationship has never been experimentally demonstrated. In the present investigation we examine if lung volume affects phonation. Twenty-four untrained subjects phonated at different pitches and degrees of vocal loudness at different lung volumes. Mean subglottal pressure was measured and voice source characteristics were analyzed by inverse filtering. The main results were that with decreasing lung volume, the closed quotient increased, while subglottal pressure, peak-to-peak flow amplitude, and glottal leakage tended to decrease. In addition, some estimates of the amount of the glottal adduction force component were examined. Possible explanations of the findings are discussed.

Adult↗

PubMed1998

Risk assessment in relation to neonatal metal exposure.

Rapid changes in organ development and function occur during the neonatal period. During this period the central nervous system is in a rapid growth rate and highly vulnerable to toxic effects of, e.g., lead and methylmercury. Furthermore, the kinetics of many metals is age-specific, with a higher gastrointestinal absorption, less effective renal excretion as well as a less effective blood-brain barrier in newborns compared to adults. Due to their low body weight and high food consumption per kg of body weight, the tissue levels of contaminants can reach higher levels in newborns than in adults. Generally, there is a low transfer of toxic metals through milk when maternal exposure levels are low. However, knowledge is limited about the lactational transport of metals and the potential effects of metals in the mammary gland on milk secretion and composition. There are some data from rodents on the lactational transfer and the uptake in the neonate of inorganic mercury, methylmercury, lead and cadmium. Metal levels in human breast milk and blood samples from different exposure situations can give information on the correlation between blood and milk levels. If such a relationship exists, milk levels can be used as an indicator of both maternal and neonatal exposure. Better understanding of the neonatal exposure, including kinetics in the lactating mother and in the newborn, and effects of toxic metals in different age groups is needed for the risk assessment. Interactions with nutritional factors and the great beneficial value of breast-feeding should also be considered.

Adult↗

PubMed1997

Dependence of jaw opening on pitch and vowel in singers.

In singing, F0 sometimes is much higher than the typical frequency value of F1. According to previous investigations, sopranos raise F1 to a frequency near F0 by widening the jaw opening in such cases. In the present study, the jaw opening was measured in 10 professional singers of different categorizations whose task was to sing an ascending two-octave scale on different vowels. Their normal F1 values for these vowels were determined at a low F0. Only for the vowels /a/ and /a/ did the singers widen the jaw opening when F0 approached the F1 value measured at a low pitch. For the other vowels, jaw opening was widened, beginning at a higher F0. It is assumed that for these vowels the singers used other articulatory means to increase F1.

Female↗

PubMed1997

Estimated subglottal pressure in six professional country singers.

Estimates of subglottal pressure in six professional male country singers were obtained during the /p/ occlusion while the subjects spoke, sang a country tune, and sang the tune of the United States national anthem. The subglottal pressure values, which were very similar in both the speech-like and singing-mode syllables, usually measured below 45 cm of water column, but they ranged as high as 59 cm. The sound pressure level in singing was also measured and was lower than that discovered in classically trained singers at high subglottal pressures.

Adult↗

PubMed1997

Physiological aspects of a vocal exercise.

The physiological aim of vocal exercises is mostly understood in intuitive terms only. This article presents an attempt to document the phonatory behavior induced by a vocal exercise. An elevated vertical position of the larynx is frequently associated with hyperfunctional phonatory habits, presumably because it induces an exaggerated vocal fold adduction. Using the multichannel electroglottograph (MEGG), the laryngeal position was determined in a group of subjects who performed a voice exercise that contained extremely prolonged versions of the consonant/b:/. This exercise is used by the coauthor (N.E.) as part of a standard vocal exercise program. Two of the seven subjects were dysphonic phonastenic patients, and the rest were normal trained or untrained persons. Different attempts to calibrate the MEGG confirmed a linear relationship with larynx height, provided electrode positioning was correct. The results showed that the exercise induced substantial vertical displacements of the larynx. Comparison with larynx height during voicing of other consonants showed that the/b/, in particular, tended to lower the larynx.

Humans↗

PubMed1996

Immunomodulating effects after perinatal exposure to methylmercury in mice.

The influence of methylmercury on the developing immune system was studied in offspring from Balb/c mice exposed to 0, 0.5 or 5 mg Hg/kg as methylmercury in the diet. Dams were exposed for 10 weeks prior to mating, during gestation and lactation. Pups were exposed to mercury until day 15 of lactation, thereafter the pups were given control milk and control diet. Samples for mercury analysis were collected from the pups on days 22 and 50, and for immunological studies on days 10, 22 and 50. The exposure resulted in significantly increased total Hg concentrations in whole blood on day 22 and 50 in offspring from the 5 mg Hg/kg group, and in offspring from the 0.5 mg Hg/kg group on day 22. On day 50, blood mercury levels had decreased to background levels in the 0.5 mg Hg/kg group. Increased numbers of splenocytes and thymocytes were found in offspring from the 0.5 mg Hg/kg group. Flow cytometry analysis of thymocytes revealed increased numbers and altered proportions of lymphocyte subpopulations within the thymus in offspring from both of the exposed groups. The proliferative response of splenocytes to the B-cell mitogen LPS was increased in offspring from dams exposed to 5 mg Hg/kg, and the primary antibody response to a viral antigen was stimulated in pups from dams exposed to 0.5 mg Hg/kg. The present results indicate that placental and lactational transfer of mercury affects thymocyte development and stimulates certain mitogen- or antigen-induced lymphocyte activities in mice.

Abnormalities, Drug-Induced↗

PubMed1996

Perturbation and hoarseness: a pilot study of six children's voices.

Fundamental frequency (FO) perturbation has been found to be useful as an acoustic correlate of the perception of dysphonia in adult voices. In a previous investigation, we showed that hoarseness in children's voices is a stable concept composed mainly of three predictors: hyperfunction, breathiness, and roughness. In the present investigation, the relation between FO perturbation and hoarseness as well as its predictors was analyzed in running speech of six children representing different degrees of hoarseness. Two perturbation measures were used: the standard deviation of the distribution of perturbation data and the mean of the absolute value of perturbation. The results revealed no clear relation.

Child↗

PubMed1996

Duration of filgrastim mobilization and apheresis yield of CD34+ progenitor cells and lymphoid subsets in normal donors for allogeneic transplantation.

Seventy-seven normal donors underwent leukapheresis for peripheral blood progenitor cell collection beginning on day 4 (n = 45) or day 5 (n = 32) of filgrastim mobilization (12 micrograms/kg/d). The two groups were comparable for age, weight, blood volumes processed during leukapheresis and target CD34+ cell dose to be collected. The day 5 schedule allowed a more consistent achievement of the target cell dose with one apheresis (P = 0.005) and resulted in the initial collection of a significantly larger number of CD34+ cells (P = 0.009). There was no statistically significant difference in the leukapheresis yield of lymphoid subsets and natural killer cells.

Adult↗

PubMed1996

Clinical toxicity and laboratory effects of granulocyte-colony-stimulating factor (filgrastim) mobilization and blood stem cell apheresis from normal donors, and analysis of charges for the procedures.

BACKGROUND: Apheresis of granulocyte-colony-stimulating factor (filgrastim)-mobilized blood stem cells from normal donors is now being used in place of a marrow harvest in transplantation. How the adverse effects of and charges for this procedure compare with those of the standard marrow harvest is not known. STUDY DESIGN AND METHODS: Forty consecutive normal subjects who received filgrastim 96 micrograms/kg) subcutaneously twice daily for 4 to 6 days in preparation for apheresis were monitored prospectively by clinical and laboratory evaluation. RESULTS: Sixty-two percent of the subjects required oral analgesics. None discontinued filgrastim prematurely. Bone pain (82%), headache (70%), fatigue (20%), and nausea (10%) were reported. Filgrastim caused a mean eightfold increase in neutrophil counts, a mean twofold increase in lymphocyte counts, a mean twofold rise in alkaline phosphatase and lactate dehydrogenase levels, and minor changes in serum potassium, magnesium, and uric acid. Adverse events and laboratory effects resolved within 7 days after apheresis. No apheresis stem cell donor required transfusion or hospitalization, and only one required an additional clinic visit after completion of apheresis. By comparison, a retrospective analysis of 33 normal marrow donors demonstrated that all received transfusion(s), 3 were hospitalized, 3 required additional clinic visits after the marrow harvest. The median total charges related to the two procedures were comparable (p = 0.43), although the charges were significantly lower for donors requiring only one apheresis procedure (p = 0.002). CONCLUSION: Filgrastim mobilization and apheresis of blood stem cells constitute a safe, well-tolerated, and comparable or less expensive alternative to the traditional marrow harvest.

Adolescent↗

PubMed1996

Allogeneic peripheral blood stem cell transplantation using normal patient-related pediatric donors.

Successful allogeneic peripheral blood progenitor cell (PBPC) transplantation has recently been reported by several transplant centers. This is a first report describing allogeneic PBPC transplantation in five patients using related pediatric donors between the ages of 4 and 13 years. Donors underwent 3 or 4 days of rhG-CSF treatment (6 micrograms/kg q 12 h) for stem cell peripheralization prior to PBPC collection, which was performed by continuous-flow apheresis on day 4 or 5. Venous access was exclusively by ante-cubital veins. A median of 2.2 times (range 1.4-3.6) the donor's total blood volume (TBV) was processed per procedure. In cases where the donor's TBV was < 2 liters, the blood cell separator was primed with human serum albumin (HSA-5%), and anticoagulation was performed using a combination of heparin (pre-apheresis bolus + continuous infusion (CI)) and/or ACD-A (CI at a reduced rate). The median number of CD34+ cells collected per kg of donor body weight (b.w.) and per liter of donor blood processed during each procedure was 128 x 10(4) (range 58 x 10(4)-314 x 10(4)). Between one and two aphereses were sufficient to collect a safe CD34+ cell engraftment dose of 3 or 4 x 10(6)/kg of recipient b.w. Two PBPC recipients were parents, and three were siblings. After freezing and thawing, the median number of CD34+ cells per kg of recipient b.w. thawed and transfused was 8.5 x 10(6) (range 3.2 x 10(6)-9.7 x 10(6)). The time to PMN > 1000/microliters was between 10 and 16 days (four out of five evaluable patients), and platelets > 20000/microliters were reached between day 13 and 14 post-transplantation (three out of five evaluable patients). Two out of three evaluable patients developed grades one and three acute GVHD, and one out of three developed chronic GVHD. Two patients died of sepsis and VOD at day 10 and 19, respectively. Two adult patients are alive and in cytogenetic and molecular remission of CML at +339 and +227 days post-allotransplantation. One 3-year-old girl with hemophagocytic lymphohistiocytosis is in remission at +304 days post-transplantation. Using pediatric donors for allogeneic PBPC transplantation appears to be safe, yields a sufficient amount of progenitors for prompt engraftment, and results in clinical outcome similar to adult PBPC allotransplantation.

Adult↗

PubMed1995

Significance of mechanoreceptors in the subglottal mucosa for subglottal pressure control in singers.

According to Wyke and Kirchner (Wyke B, Kirchner J. Neurology of the larynx. In: Hinchcliffe R, Harrison D, eds. Scientific foundation of otolaryngology. London: William Heinemann Medical Books, 1976:546-66) mechanoreceptors in the subglottal mucosa play a significant role in the control of laryngeal muscle activity in response to changes of subglottal pressure during phonation. In singers this pressure is adapted not only to phonatory loudness but also to fundamental frequency. By spraying Xylocaine solution with a needle inserted into the trachea through the anterior gap between the cricoid and thyroid cartilages, the subglottal mucosa was anesthetized in three singers. The effects on subglottal pressure and fundamental frequency of this anesthesia were examined. The pressure effects varied between the subjects, whereas the fundamental frequency accuracy was adversely affected in all three subjects. The implications of these findings are discussed.

Adult↗

PubMed1995

What happens during vocal warm-up?

Most singers prefer to warm up their voices before performing. Although the subjective effect is often considerable, the underlying physiological effects are largely unknown. Because warm-up tends to increase blood flow in muscles, it seems likely that vocal warm-up might induce decreased viscosity in the vocal folds. According to the theory of vocal-fold vibration, such a decrease should lead to a lower phonation threshold pressure. In this investigation the effect of vocal warm-up on the phonation threshold pressure was examined in a group of male and female singers. The effect varied considerably between subjects, presumably because the vocal-fold viscosity was not a dominating factor for the phonation-threshold pressure.

Adult↗

PubMed1995

Exposure to toxic elements via breast milk.

Breast milk is the ideal nutrient for the newborn, but unfortunately also a route of excretion for some toxic substances. Very little attention has been paid to breast milk as a source of exposure to toxic elements. The dose-dependent excretion is breast milk and the uptake in the neonate of inorganic mercury, methylmercury and lead were studied in an experimental model for rats and mice. The transfer of mercury from plasma to milk was found to be higher in dams exposed to inorganic mercury than to methylmercury. In contrast, the uptake of mercury from milk was higher in the sucklings of dams exposed to methylmercury than to inorganic mercury. Pre- and postnatal exposure to methylmercury resulted in increased numbers and altered proportions of the thymocyte subpopulation and increased lymphocyte activities in the offspring of mice and also effects on the levels of noradrenaline and nerve growth factor in the developing brain of rats. Mercury in blood and breast milk in lactating women in Sweden was studied in relation to the exposure to mercury from, fish and amalgam. Low levels were found; the mean levels were 0.6 ng g-1 in milk and 2.3 ng g-1 in blood. There was a statistically significant correlation between mercury levels in blood and milk, showing that milk levels were approximately 30% of the levels in blood. Inorganic mercury exposure from amalgam was reflected in blood and milk mercury levels. Recent exposure to methylmercury from consumption of fish was reflected in mercury levels in the blood but not in milk.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Vocal fold vibration patterns and modes of phonation.

Voice source characteristics of some different modes of phonation as produced by a trained voice are combined with an analysis of the same singer's vocal fold vibrations as recorded by a digital high-speed imaging technique. Considerable differences between modes are found with regard to the waveform and amplitude of vocal fold vibration. The results support the assumption that the physiological input parameter underlying differences in mode of phonation is glottal adduction.

Humans↗

PubMed1995

Aetiologic factors associated with hoarseness in ten-year-old children.

The parents of 55 10-year-old children answered questionnaires concerning 51 elements of potential relevance to voice function such as vocal habits, speech and language development, medical history, social history, physical environment and family relations. In addition, personality profiles of each child were assessed by its teacher and parents. The results were compared to an expert listening panel's evaluation of hoarseness and vocal-fold status as determined by a visual examination by a phoniatrician. Eight boys were identified as being chronically hoarse. Gender, personality and hours spent per day in large groups were highly significant factors associated with hoarseness. A discriminant analysis based on the significant background variables correctly grouped 86.3% of the children.

Child↗