Intracellular calcium during fatigue of cane toad skeletal muscle in the absence of glucose

Mechanisms of fatigue were studied in single muscle fibres of the cane toad (Bufo marinus) in which force, intracellular calcium ([Ca2+]i), [Mg2+]i, glycogen and the rapidly releasable Ca2+ from the sarcoplasmic reticulum (SR) were measured. Fatigue was produced by repeated tetani continued until force had fallen to 50%. Two patterns of fatigue in the absence of glucose were studied. In the first fatigue run force fell to 50% in 8-10 min. Fatigue runs were then repeated until force fell to 50% in < 3 min in the final fatigue run. Addition of extracellular glucose after the final fatigue run prolonged a subsequent fatigue run. In the first fatigue run peak tetanic [Ca2+]i initially increased and then declined and at the time when force had fallen to 50% tetanic [Ca2+]i was 54+/-5% of initial value. In the final fatigue run force and peak tetanic [Ca2+]i declined more rapidly but to the same level as in first fatigue runs. At the end of the first fatigue run, the rapidly releasable SR Ca2+ store fell to 46+/-6% of the pre-fatigue value. At the end of the final fatigue run the rapidly releasable SR Ca2+ store was 109+/-16% of the pre-fatigue value. In unstimulated fibres the nonwashable glycogen content was 176+/-30 mmol glycosyl units/l fibre. After one fatigue run the glycogen content was 117+/-17 mmol glycosyl units/l fibre; at the end of the final fatigue run the glycogen content was reduced to 85+/-9 mmol glycosyl units/l fibre. [Mg2+]i did not change significantly at the end of fatigue in either the first or the final fatigue run suggesting that globally-averaged ATP does not decline substantially in either pattern of fatigue. These results suggest that different mechanisms are involved in the decline of tetanic [Ca2+]i in first compared to final fatigue runs. The SR Ca2+ store is reduced in first fatigue runs; this is not the case for the final fatigue run which is associated with a decline in glycogen and possibly related to either a non-metabolic effect of glycogen or a spatially-localised metabolic decline.

Comparative sensitivity of embryo-larval toxicity assays with African catfish (Clarias gariepinus) and zebra fish (Danio rerio)

Embryo-larval toxicity tests with the African catfish (Clarias gariepinus) were conducted with five chemicals (Cr, Cd, Zn, NaPCP and malathion) and three environmental samples. The sensitivity of the 5-day assay was compared to that of the 12-day embryo-larval toxicity tests with the zebra fish (Danio rerio). The ratios of the C. gariepinus and D. rerio LC50 values ranged from 0.4 for Cr to 8.9 for Zn. The ratios of subchronic values ranged from 0.25 for NaPCP to 3.1 for Cd indicating a more comparable sensitivity of the two species. For the three sediment pore waters, the ratios were 0.6, 1.1, and 2.4 and the subchronic values were identical for the two species. The results suggest that, considering the short-test duration and its sensitivity, the 5-day embryo-larval tests with C. gariepinus may be a potential alternative for short-term embryo-larval toxicity testing with fish.

Detection of cytochrome P450 and other drug-metabolizing enzyme mRNAs in peripheral blood mononuclear cells using DNA arrays

The purpose of this study was to determine whether the expression of cytochrome P450 (CYP) enzyme mRNAs, other drug-metabolizing enzyme mRNAs, and transporter mRNAs can be detected using DNA arrays. Total RNA was isolated from peripheral blood mononuclear cells of 10 multiple sclerosis patients and 10 age- and sex-matched controls. The mRNA was reverse transcribed to radiolabeled cDNA, and the resultant cDNA was used to probe a DNA array containing several thousand known human genes. The signals corresponding to several CYPs, drug-metabolizing, and transporter mRNAs was substantially above background. The results demonstrate that the DNA array technique has the sensitivity and the selectivity for applications in the pharmaceutical sciences. The mean values for mRNAs of specific CYPs and drug-metabolizing enzymes in peripheral blood cells were compared with reported values for liver. The capabilities of DNA arrays may prove useful for characterizing CYP expression in a variety of clinical samples.

Normocalcemic hyperparathyroidism in Vietnamese immigrants living in southern California

OBJECTIVE

To characterize the normocalcemic hyperparathyroidism in Vietnamese immigrants living in southern California.

METHODS

Of 14 Vietnamese patients with primary hyperparathyroidism who were observed between 1991 and 1996, 50% (7 patients; 2 men and 5 women) had normal and/or fluctuating levels of serum total calcium. When the serum calcium was corrected for the albumin, the "corrected" calcium was lower than the measured serum total calcium. Their mean age was 56.4 +/- 11.4 years. All patients had normal serum levels of albumin and serum phosphate.

RESULTS

Women were affected more often than men by a ratio of 5:2. The serum-ionized calcium as well as intact PTH were increased in all patients. Five patients underwent surgery with confirmation of parathyroid adenomas. Two patients refused surgery. They did not have osteitis fibrosa cystica by radiological examination. One patient had low plasma levels of 25-hydroxyvitamin D. Five of 7 normocalcemic patients (70%) were born in the month of December compared with 2 of seven hypercalcemic patients (30%).

CONCLUSION

The blood ionized calcium and intact parathyroid hormone are necessary for confirmation of normocalcemic hyperparathyroidism. Most of our normocalcemic hyperparathyroid patients (70%) were born in the month of December. We postulate that a combination of exposure to solar ultraviolet light during the formation of the fetal parathyroid glands and stimulation from low vitamin D levels in the wintertime may be related to the development of hyperparathyroidism. However, it is difficult to prove a definite correlation between normocalcemic hyperparathyroidism and their month of birth (December), especially when these observations were seen in a small group of patients.

Localization of choline acetyltransferase in the developing and adult turtle retinas

Acetylcholine has important epigenetic roles in the developing retina. In this study, cells that expressed choline acetyltransferase (ChAT), the enzyme that synthesizes acetylcholine, were investigated in embryonic, postnatal, and adult turtle retinas by using immunofluorescence histochemistry. ChAT was present at stage 15 (S15) in cells near the vitreal surface. With the formation of the inner plexiform layer (IPL) at S18, ChAT-immunoreactive (-IR) cells were located in the inner nuclear layer (INL) and the ganglion cell layer (GCL). In the INL, presumed starburst amacrine cells were homogenous in appearance and formed a single row next to the IPL: This pattern was conserved until adulthood. In the GCL, however, there were multiple rows of ChAT-IR cells early in development, and this high density of labeled cells continued during the embryonic stages, until around birth. The high density of ChAT-IR cells in the GCL was due in part to a population of cells that expressed ChAT transiently. In postnatal stages and adult retinas, the presumed starburst amacrine ChAT-IR cells formed two mirror-like rows of homogenous cells on both borders of the IPL. Two cholinergic dendritic strata that were continuous with these cells were observed as early as S18, and their depths in the IPL were relatively stable throughout development. A third population of ChAT-IR cells was observed toward the middle of the INL around S25 and persisted into adulthood. Finally, cells in the outer nuclear layer (ONL) were ChAT-IR during the embryonic stages, were less immunoreactive during the postnatal stages, and were not immunoreactive in the adult retinas.

Colocalization of choline acetyltransferase and gamma-aminobutyric acid in the developing and adult turtle retinas

Acetylcholine and gamma -aminobutyric acid (GABA) are putative neurotransmitters in the adult vertebrate retina. In this study, cells that coexpress choline acetyltransferase (ChAT) and GABA or glutamic acid decarboxylase (GAD) were investigated in turtle retinas from stage 14 (S14) to adulthood by using a double-labeling immunofluorescence technique. ChAT immunoreactivity was observed at S15 and included not only the presumptive starburst cholinergic amacrine cells but also a population in the ganglion cell layer (GCL) that expressed ChAT transiently during the embryonic stages (see the accompanying paper: Nguyen et al. [2000] J. Comp. Neurol. 420:512-526).

Should malrotation in children be treated differently according to age?

PURPOSE

The aim of this study was to better define the mode of presentation, rate of volvulus, and surgical findings in children younger than 2 versus older than 2 years of age with malrotation.

METHODS

The authors reviewed the charts of all patients with malrotation admitted to their hospital between January 1980 and December 1998, excluding patients having malrotation as a secondary finding.

RESULTS

An upper gastrointestinal series was done in 90 patients (6% falsely negative) and a barium enema in 20 patients (40% read as normal). Fifty-eight patients had 114 associated congenital anomalies. Volvulus was found at the time of surgery in 28 patients, 5 of whom were older than 2 years. Three presented with acute symptoms and 2 with chronic symptoms. Surgery was performed by laparotomy in 103 patients and by laparoscopy in 3. Mean length of stay was 13.6 days. Mean follow-up was 19 months. Death occurred in 4 patients; postoperative bowel obstruction was seen in 3 patients (only 1 required surgery).

CONCLUSIONS

Children with malrotation who are older than 2 years old have a significant risk of volvulus that is difficult to predict radiologically. They require surgical attention even if asymptomatic. Laparoscopy allows evaluation of the base of the mesentery and completion of the Ladd's procedure.

Delayed presentation of a congenital recto-vaginal fistula associated with a recto-sigmoid tubular duplication and spinal cord and vertebral anomalies

Tubular duplication of the recto-sigmoid colon is a rare entity. Associated anomalies including fistulae to the genitourinary tract may be found. A baby girl was found to have duplication of the recto-sigmoid colon, anomalies of sacral vertebra from S1 to S5, and solitary right kidney. The septum of this duplication was divided using staplers. Because of a history of stool coming from the vagina, a meticulous examination perioperatively was performed, but no fistula could be found. Further extensive investigation failed to show any fistula. At the age of 10 she was operated on for a tethered cord. At age 14, she experienced passage of a small amount of liquid stool per vaginum. A recto-vaginal fistula was found. Via a posterior sagittal incision, the fistula was closed by a transrectal approach. She remained asymptomatic for 16 months until the fistula recurred. Using a perineal approach, a very short fistula between the vagina and the rectum was closed. The closure was reinforced by a vaginal flap. Four months later, she remains without signs of recurrence.

Cross-correlation for flow cytometric histogram background subtractions

Background subtraction is a widely encountered problem in flow cytometry applications for which the currently available analysis techniques are unsatisfactory. The 99% division line method, also referred to as the threshold or marker method, is widely used because it is computationally simple but it has poor accuracy and tends to underestimate the percentage of positive cells when there is overlap between histograms. Model-based approaches are preferred when there are overlapping peaks, but these methods require curve fitting and strong assumptions regarding the shape of the underlying distributions. This report assesses a mathematically rigorous, computationally facile, non-parametric technique called cross correlation for the background subtraction problem. A metric, positivity, derived from cross correlation is shown to overcome the disadvantages of both the 99% division line and model-based methods without compromise.

Hyperthyroidism and asthma

Two patients presented with new onset of thyrotoxicosis and they then developed episodic wheezing a few months afterward. The asthmatic attacks improved when the patients were rendered in a euthyroid state with treatment. The present paper discusses the relationship between two diseases, hyperthyroidism and asthma, and the underlying factors potentially contributing to their conditions. The present findings suggest that asthma may develop in a susceptible individual with hyperthyroidism and it is possible that the reactive oxygen species may be a contributory factor in exacerbating wheezing in our hyperthyroid patients.

TNF receptor 1 (TNFR1) and CD95 are not required for T cell deletion after virus infection but contribute to peptide-induced deletion under limited conditions

Deletion of mature T cells maintains cellular homeostasis and is involved in the maintenance of self tolerance to some peripheral self antigens. Previous studies have presented conflicting evidence for a role of the tumor necrosis factor receptor (TNFR) family member CD95 (Fas) in peripheral T cell deletion using CD95-deficient mice. To evaluate cooperation between CD95 and another TNFR family molecule, TNFR1, we generated mice deficient for both CD95 and TNFR1. We showed that TNFR1 and CD95 do not contribute to the decline of antigen-specific cytotoxic T lymphocytes after virus infection. Using TNFR1 / CD95-deficient mice expressing the P14 TCR specific for a lymphocytic choriomeningitis virus-derived peptide (p33) we showed that deletion of p33-specific CD8(+) T cells following high dose p33 administration is also normal. However, in non-TCR-transgenic TNFR1 / CD95-deficient mice treated with the same p33 regimen, tolerance induction was defective. These data indicate that TNFR1 and CD95 are dispensable for deletion of antigen-specific T cells after viral infection. However, under certain conditions, both TNFR1 and CD95 appear to cooperate in CD8(+) T cell deletion.

Links between Fer tyrosine kinase expression levels and prostate cell proliferation

In our cloning strategy to identify tyrosine kinases implicated in the regulation of prostate growth, the dog fer cDNA was obtained and shown to be highly homologous to known fer cDNAs. Using a polyclonal Fer antibody directed against a C-terminal peptide, we studied its associations with cortactin, beta-catenin and p120Cas in human prostate carcinoma PC-3 cells. In contrast to previous reports, no interactions were observed. To assess its functional role, fer cDNA constructs were transfected in PC-3 cells. Antisense clones exhibiting a marked diminution of Fer expression had a reduced growth rate (doubling time of 29 vs. 42 h) and were unable to form colonies in soft agar. In agreement with these results, Fer protein expression was linked to human prostatic proliferative diseases, with enhanced levels in extracts from cancer tissues as compared to those from normal and hyperplastic ones, and was also expressed in the human prostate carcinoma cell lines DU145 and LNCaP. In the dog model, Fer expression was up-regulated in dividing versus resting prostate epithelial cells in vitro, and also in vivo when basal cell hyperplasia and metaplasia was induced by estrogen after castration. Minimal effects were observed when renewing the luminal epithelium with androgens. Taken together, these results show that Fer expression is associated with prostate cell proliferation and enhanced in prostate cancer.

Folate and vitamin B12-deficiency anemias in Vietnamese immigrants living in Southern California

BACKGROUND

Although the occurrence of iron deficiency anemia and hemoglobinopathies in Vietnamese immigrants has been reported, folate and vitamin B12 deficiencies have not. Proper diagnosis and effective treatment is necessary to achieve a complete correction of anemia.

METHODS

We retrospectively analyzed the records of Vietnamese immigrants seen in our medical clinic from 1991 to 1993. Fifty-nine anemic patients (48 females and 11 males) had low levels of red blood cell (RBC) folate and/or serum vitamin B12.

RESULTS

The patients' mean age was 37.7+/-17 years. Mean hemoglobin and hematocrit values were 11.4+/-0.7 g/dL and 34.4%+/-2.2%, respectively. Mean corpuscular volume (MCV) was normal in 40 patients (68%) (mean, 89.1+/-5 fL) and low in 19 patients (32%) (mean, 69.7+/-6 fL). Forty-four patients had low RBC folate levels (mean, 157.7+/-41.7 ng/mL). Twenty patients had low serum vitamin B12 levels (mean, 165.6+/-47 pg/mL). Fourteen patients had ferritin levels of <20%.

CONCLUSIONS

Concomitant folate, vitamin B12, and iron deficiencies or hemoglobinopathies might have been responsible for either normal or low MCV in some of our anemic patients. In this ethnic group, RBC folate and serum vitamin B12 levels should be determined in all anemic patients.

Activated T cells regulate bone loss and joint destruction in adjuvant arthritis through osteoprotegerin ligand

Bone remodelling and bone loss are controlled by a balance between the tumour necrosis factor family molecule osteoprotegerin ligand (OPGL) and its decoy receptor osteoprotegerin (OPG). In addition, OPGL regulates lymph node organogenesis, lymphocyte development and interactions between T cells and dendritic cells in the immune system. The OPGL receptor, RANK, is expressed on chondrocytes, osteoclast precursors and mature osteoclasts. OPGL expression in T cells is induced by antigen receptor engagement, which suggests that activated T cells may influence bone metabolism through OPGL and RANK. Here we report that activated T cells can directly trigger osteoclastogenesis through OPGL. Systemic activation of T cells in vivo leads to an OPGL-mediated increase in osteoclastogenesis and bone loss. In a T-cell-dependent model of rat adjuvant arthritis characterized by severe joint inflammation, bone and cartilage destruction and crippling, blocking of OPGL through osteoprotegerin treatment at the onset of disease prevents bone and cartilage destruction but not inflammation. These results show that both systemic and local T-cell activation can lead to OPGL production and subsequent bone loss, and they provide a novel paradigm for T cells as regulators of bone physiology.

25 years' experience with lymphangiomas in children

BACKGROUND/PURPOSE

The management of lymphangioma in children is challenging because complete resection is difficult to achieve in some cases, and recurrences are common. The authors reviewed their experience to assess the risk factors for recurrence and the role of nonoperative treatment.

METHODS

A retrospective study over a period of 25 years was carried out. One hundred eighty-six patients with 191 lesions (five patients with de novo lesions in different sites) were treated. There were 98 boys and 88 girls. The average age at diagnosis was 3.3 years (range, fetal life to 17 years) and the average size 8 cm in diameter. Histocytological confirmation was obtained in all patients. The involved sites were head and neck, 89 patients (48%); trunk and extremities, 78 patients (42%); internal or visceral locations (eg, abdominal and thorax), 19 patients (10%). The treatment consisted of macroscopically complete excision in 145 patients (150 lesions, of which five were recurrences in different sites), partial excision in 10 patients, aspiration in five patients, laser excision in 10 patients, biopsy only in four patients, drainage and biopsy in two patients, and injection of sclerosing agents in 10 patients.

RESULTS

There were 54 recurrences; 44 underwent excision (five of them more than once), and five regressed spontaneously on follow-up. Five other recurrences were stable and not progressing. Recurrences, (defined as clinically obvious disease), were found to be 100% after aspiration, 100% after injection, 40% after incomplete excision, 40% after laser excision, and 17% after macroscopically complete excision. The recurrence rate in the last group was the highest in the head (33%), the least in the internal locations (0%), and intermediate for the cervical location (13%). There were no significant differences, in terms of outcome, between those who had their surgery immediately at the time of diagnosis (n = 101) and those who had delayed surgery (n = 85).

CONCLUSIONS

There were fewer recurrences after macroscopically complete excision. Aspiration and injection had the highest recurrence rate. Risk factors for recurrence included location, size, and complexity of lesions. A period of observation may be useful for infants to facilitate complete excision. In the present series, spontaneous regression was infrequent and was seen more often with recurrent lesions.

Increased resting energy expenditure is related to plasma TNF-alpha concentration in stable COPD patients

The objective of this study was to test whether increased resting energy expenditure (REE) in chronic obstructive pulmonary disease (COPD) patients is related to increased cost of breathing and/or to increased cytokine production. In 36 non-inflammatory (CRP: 17.6 +/- 13.1 mg.l(-1), mean +/- SD; orosomucoid: 0.71 +/- 0.18 g.l(-1)), non-malnourished (BMI: 23.6 +/- 4.3 kg.m(-2)), clinically stable, non severely hypoxic COPD patients (60.5 +/- 8.9 years) we measured REE, pulmonary function and plasma cytokine concentrations (TNF-alpha, IL1 and IL6). REE was increased by 10 +/- 11% (P< 0.001) above predicted values. Plasma TNF-alpha concentration was increased in all patients (mean value 26.3 +/- 14.3 pg.ml(-1)). Excess REE (with respect to values predicted by Harris-Benedict equations) was correlated with plasma TNF-alpha concentration (P< 0.005), but not with the degree of airway obstruction, lung overinflation, or with oxygen cost of breathing. Theophylline treatment resulted in a significant increase in REE by 15%.

IN CONCLUSION

non-malnourished, clinically stable, non-severely hypoxic COPD patients display an increased REE that is related with plasma TNF-alpha concentration (without apparent systemic inflammation) and to theophylline treatment, but that is independent of parameters of respiratory function.

An electrophoretic study of myosin heavy chain expression in skeletal muscles of the toad Bufo marinus

In this study we developed an SDS-PAGE protocol which for the first time separates effectively all myosin heavy chain (MHC) isoforms expected to be expressed in iliofibularis (IF), pyriformis (PYR), cruralis (CRU) and sartorius (SAR) muscles of the toad Bufo marinus on the basis of previously reported fibre type composition. The main feature of the method is the use of alanine instead of glycine both in the separating gel and in the running buffer. The correlation between the MHC isoform composition of IF, SAR and PYR muscles determined in this study and the previously reported fibre type composition of IF and SAR muscles in the toad and of PYR muscle in the frog was used to tentatively identify the MHC isoforms expressed by twitch fibre types 1, 2 and 3 and by tonic fibres. The alanine-SDS electrophoretic method was employed to examine changes in the MHC composition of IF, PYR, CRU and SAR muscles with the ontogenetic growth of the toad from post-natal life (body weight < 1 g) to late adulthood (body weight 200-450 g). The developmental changes in the MHC isoform composition of the toad IF muscle observed in this study are in very good agreement with those in the fibre type composition of the developing IF muscle reported in the literature.

TRAF2 deficiency results in hyperactivity of certain TNFR1 signals and impairment of CD40-mediated responses

Tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2) can interact with various members of the TNF receptor family. Previously, we reported that TRAF2-deficient mice die prematurely and have elevated serum TNF levels. In this study, we demonstrate that TRAF2-deficient macrophages produce increased amounts of nitric oxide (NO) and TNF in response to TNF stimulation. Furthermore, we could enhance the survival of TRAF2-deficient mice by eliminating either TNF or TNFR1. Using these double-knockout mice, we show that in the absence of TRAF2, the T helper-dependent antibody response, CD40-mediated proliferation, and NF-kappaB activation are defective. These data demonstrate two important roles of TRAF2, one as a negative regulator of certain TNFR1 signals and the other as a positive mediator of CD40 signaling.

Abducens internuclear and ascending tract of Deiters inputs to medial rectus motoneurons in the cat oculomotor nucleus: neurotransmitters

The abducens internuclear and ascending tract of Deiters (ATD) pathways are the principal excitatory inputs to medial rectus motoneurons in the oculomotor nucleus and are related to the control of conjugate horizontal eye movements. Differences in the morphology and soma-dendritic distribution of abducens internuclear and ATD synaptic endings are correlated with known differences in the physiological properties of these independent inputs. The present study extends these observations to the ultrastructural localization of the excitatory amino acid neurotransmitters, glutamate and aspartate, using a postembedding immunogold procedure combined with the pre-embedding immunoperoxidase localization of anterogradely transported biocytin from the abducens nucleus and the ventral lateral vestibular nucleus. Consistent with their spheroidal synaptic vesicle content and the asymmetric pre/postsynaptic membrane profile, both the abducens internuclear and ATD synaptic endings are labeled with glutamate and aspartate. However, quantitative analysis of the density of colloidal gold particles associated with mitochondria versus synaptic vesicles/axoplasmic matrix reveals significant differences in the metabolic versus neurotransmitter pools of the amino acids in the two populations of synaptic endings. The findings indicate that both aspartate and glutamate, possibly co-localized, are the excitatory neurotransmitters utilized by abducens internuclear synaptic endings whose burst-tonic physiological activity conveys information related to eye position to medial rectus motoneurons. By contrast, glutamate is the excitatory neurotransmitter associated with ATD synaptic endings whose high frequency burst activity is related to head velocity.

Glycogen content and excitation-contraction coupling in mechanically skinned muscle fibres of the cane toad

1. Mechanically skinned skeletal muscle fibres from the twitch region of the iliofibularis muscle of cane toads were used to investigate the relationship between fibre glycogen content and fibre capacity to respond to transverse tubular (T-) system depolarization. 2. A large proportion of total fibre glycogen remained in mechanically skinned muscle fibres exposed to aqueous solutions. This glycogen pool (about 80% of total fibre glycogen) was very stable when the preparation was incubated in a rigor solution (pH 7.0) but decreased gradually at a rate of 0.59+/-0.20% min-1 in a relaxing solution (200 nM [Ca2+]). The rate was considerably higher (2.66+/-0.38% min(-1)) when the preparations were exposed to 30 microM [Ca2+]. An even greater rate of glycogen loss was found after T-system depolarization-induced contractions. The Ca2+-dependent loss of fibre glycogen was caused by endogenous glycogenolytic processes. 3. Silver stained SDS gels of components eluted into relaxing solution from single skinned fibres revealed a rapid (2 min) loss of parvalbumin and at least 10 other proteins varying in molecular mass between 10 and 80 kDa but there was essentially no loss of myosin heavy and light chains and actin. Subsequent elution for a further 30 min in either relaxing or maximally Ca2+-activating solution did not result in additional, appreciable detectable loss of fibre protein. 4. Depletion of fibre glycogen was associated with loss of fibre ability to respond to T-system depolarization even though the bathing solutions contained high levels of ATP (8 mM) and creatine phosphate (10 mM). 5. The capacity of mechanically skinned fibres to respond to T-system depolarization was highly positively correlated (P<0.0001) with initial fibre glycogen concentration. 6. In conclusion, the results show that (i) the capacity of skeletal muscle to respond to T-system depolarization is related directly or indirectly to the non-washable glycogen pool in fibres, (ii) this relationship holds for conditions where glycogen is not required as a source of energy and (iii) the mechanically skinned fibre preparation is well suited to study the regulation of endogenous glycogenolytic enzymes.

Pharmaceutical container/closure integrity. IV: Development of an indirect correlation between vacuum decay leak measurement and microbial ingress

The rational development of a physical test method to evaluate the microbial barrier properties of sterile containers necessitates its correlation to microbiological exclusion. This can be accomplished by direct or indirect correlation. In the former, the proposed physical test is directly compared to microbial challenges using appropriate test units that stimulate container leaks at both high and low probabilities of microbial ingress. Previous work has demonstrated the development of a direct correlation using helium leak rate methods and microbial immersion challenges. An indirect correlation can be established by comparing the proposed physical method to well-defined leakage standards that represent various known levels of microbial ingress. Thus the quality assurance properties of a physical test method can be established by comparison to another physical test method that has been previously characterized. This approach has the distinct advantages of being faster, quantitatively rigorous, and less subject to the vicissitudes, of microbial testing. This approach was demonstrated by comparing the helium leak rate method to vacuum decay testing. Additionally it was demonstrated that vacuum decay testing was a fast and reproducible method for detecting leaks of about 1 to 2 mm. Leaks were simulated by affixing micropipettes into glass vials.

25 years' experience with lymphangiomas in children

BACKGROUND/PURPOSE

The management of lymphangioma in children is challenging because complete resection is difficult to achieve in some cases, and recurrences are common. The authors reviewed their experience to assess the risk factors for recurrence and the role of nonoperative treatment.

METHODS

A retrospective study over a period of 25 years was carried out. One hundred eighty-six patients with 191 lesions (five patients with de novo lesions in different sites) were treated. There were 98 boys and 88 girls. The average age at diagnosis was 3.3 years (range, fetal life to 17 years) and the average size 8 cm in diameter. Histocytological confirmation was obtained in all patients. The involved sites were head and neck, 89 patients (48%); trunk and extremities, 78 patients (42%); internal or visceral locations (eg, abdominal and thorax), 19 patients (10%). The treatment consisted of macroscopically complete excision in 145 patients (150 lesions, of which five were recurrences in different sites), partial excision in 10 patients, aspiration in five patients, laser excision in 10 patients, biopsy only in four patients, drainage and biopsy in two patients, and injection of sclerosing agents in 10 patients.

RESULTS

There were 54 recurrences; 44 underwent excision (five of them more than once), and five regressed spontaneously on follow-up. Five other recurrences were stable and not progressing. Recurrences, (defined as clinically obvious disease), were found to be 100% after aspiration, 100% after injection, 40% after incomplete excision, 40% after laser excision, and 17% after macroscopically complete excision. The recurrence rate in the last group was the highest in the head (33%), the least in the internal locations (0%), and intermediate for the cervical location (13%). There were no significant differences, in terms of outcome, between those who had their surgery immediately at the time of diagnosis (n = 101) and those who had delayed surgery (n = 85).

CONCLUSIONS

There were fewer recurrences after macroscopically complete excision. Aspiration and injection had the highest recurrence rate. Risk factors for recurrence included location, size, and complexity of lesions. A period of observation may be useful for infants to facilitate complete excision. In the present series, spontaneous regression was infrequent and was seen more often with recurrent lesions.

Evaluation of pulmonary function in workers exposed to hexamethylene diisocyanate

Production of hexamethylene diisocyanate (HDI) biuret and trimer from HDI monomer was started in 1988 at the plant under study. Pulmonary function tests were included as part of the annual evaluation of the workers in that unit. HDI is expected to have toxic properties similar to those of toluene diisocyanate. The latter has caused accelerated declines in pulmonary function in exposed workers. In 1991, an initial longitudinal evaluation of those pulmonary function tests was performed, comparing annual declines in forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). The purpose of the study was to evaluate whether or not exposures to HDI at the unit had caused any accelerated decline in FVC or FEV1. No significant differences were seen in that evaluation, but it was decided that the study be continued in a prospective fashion. The study has been continued through 1997. The slope of the annual change in FVC and FEV1 were calculated for a group of workers and a matched control group. The average annual decline in FVC for the exposed group (cases) was 0.026 L, compared with 0.025 L for the control group. For the decline in FEV1, the results were 0.044 L, compared with 0.041 L (P = 0.79). These results are virtually identical and support a conclusion that exposures within this unit to HDI have not caused an accelerated decline in FVC or FEV1. Exposures to HDI were measured during this period. The time-weighted average exposure to HDI during work not requiring respiratory protection in the unit (approximately 2 hours per day) was 0.5 parts per billion. The average daily high peak exposure was 2.9 parts per billion. Exposure to these levels appear to pose no risk of accelerated decline in pulmonary function.

Flow cytometric analysis of in vitro proinflammatory cytokine secretion in peripheral blood from multiple sclerosis patients

The cytokines, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and interleukin-2 (IL-2) are important endogenous proinflammatory proteins and have been linked to disease activity in multiple sclerosis. In this study, we use flow cytometric methodology to compare the secretion of IFN-gamma, IL-2, and TNF-alpha from peripheral blood-derived T cells of multiple sclerosis patients to the secretion in healthy controls. The percentages of IFN-gamma, IL-2, and TNF-alpha secreting cells are not significantly different between multiple sclerosis patients and controls. However, the TNF-alpha secreting CD3 cell percentage is correlated with the IFN-gamma and IL-2 secreting CD3 cell percentages in multiple sclerosis patients. In the controls, only the TNF-alpha secreting CD3 cell percentage is correlated with IFN-gamma. These findings show that correlated secretion of cytokines occurs in multiple sclerosis and suggest that concerted intercytokine interactions may play an important role in the disease.