Repression of hybrid dysgenesis in Drosophila melanogaster by combinations of telomeric P-element reporters and naturally occurring P elements

In Drosophila melanogaster, hybrid dysgenesis occurs in the germline of flies produced by crosses between females lacking P elements and males carrying 25-55 P elements. We have previously shown that a complete maternally inherited repression of P transposition in the germline (P cytotype) can be elicited by only two autonomous P elements located at the X chromosome telomere (cytological site 1A). We have tested whether P transgenes at 1A, unable to code for a P-repressor, may contribute to the repression of P elements. Females carrying a P-lacZ transgene at 1A ["P-lacZ(1A)"], crossed with P males, do not repress dysgenic sterility in their progeny. However, these P-lacZ(1A) insertions, maternally or paternally inherited, contribute to P-element repression when they are combined with other regulatory P elements. This combination effect is not seen when the P-lacZ transgene is located in pericentromeric heterochromatin or in euchromatin; however a P-w,ry transgene located at the 3R chromosome telomere exhibits the combination effect. The combination effect with the P-lacZ(1A) transgene is impaired by a mutant Su(var)205 allele known to impair the repression ability of the autonomous P elements at 1A. We hypothesized that the combination effect is due to modification of the chromatin structure or nuclear location of genomic P elements.

Synaptic physiology and mitochondrial function in crayfish tonic and phasic motor neurons

Phasic and tonic motor neurons of crustaceans differ strikingly in their junctional synaptic physiology. Tonic neurons generally produce small excitatory postsynaptic potentials (EPSPs) that facilitate strongly as stimulation frequency is increased, and normally show no synaptic depression. In contrast, phasic neurons produce relatively large EPSPs with weak frequency facilitation and pronounced depression. We addressed the hypothesis that mitochondrial function is an important determinant of the features of synaptic transmission in these neurons. Mitochondrial fluorescence was measured with confocal microscopy in phasic and tonic axons and terminals of abdominal and leg muscles after exposure to supravital mitochondrial fluorochromes, rhodamine-123 (Rh123) and 4-diethylaminostyryl-N-methylpyridinium iodide (4-Di-2-Asp). Mitochondria of tonic axons and neuromuscular junctions had significantly higher mean Rh123 and 4-Di-2-Asp fluorescence than in phasic neurons, indicating more accumulation of the fluorochromes. Mitochondrial membrane potential, which is responsible for Rh123 uptake and is related to mitochondrial oxidative activity (the production of ATP by oxidation of metabolic substrates), is likely higher in tonic axons. Electron microscopy showed that tonic axons contain approximately fivefold more mitochondria per microm2 cross-sectional area than phasic axons. Neuromuscular junctions of tonic axons also have a much higher mitochondrial content than those of phasic axons. We tested the hypothesis that synaptic fatigue resistance is dependent on mitochondrial function in crayfish motor axons. Impairment of mitochondrial function by uncouplers of oxidative phosphorylation, dinitrophenol or carbonyl cyanide m-chlorophenylhydrazone, or by the electron transport inhibitor sodium azide, led to marked synaptic depression of a tonic axon and accelerated depression of a phasic axon during maintained stimulation. Iodoacetate, an inhibitor of glycolysis, and chloramphenicol, a mitochondrial protein synthesis inhibitor, had no significant effects on either mitochondrial fluorescence or synaptic depression in tonic or phasic axons. Collectively, the results provide evidence that mitochondrial oxidative metabolism is important for sustaining synaptic transmission during maintained stimulation of tonic and phasic motor neurons. Tonic neurons have a higher mitochondrial content and greater oxidative activity; these features are correlated with their greater resistance to synaptic depression. Conversely, phasic neurons have a lower mitochondrial content, less oxidative activity, and greater synaptic fatigability.

Quantal release at visualized terminals of a crayfish motor axon: intraterminal and regional differences

Synaptic transmission was measured at visualized terminal varicosities of the motor axon providing the sole excitatory innervation of the "opener" muscle in walking legs of crayfish (Procambarus clarkii Girard). Two questions were addressed: 1) How uniform is quantal emission at different locations along terminals innervating a single muscle fiber, and 2) can differences in quantal emission account for the different excitatory postsynaptic potential (EPSP) amplitudes generated by terminals localized in defined regions of the muscle? Extracellular "macropatch" electrodes were placed over individual varicosities, viewed after brief exposure to a fluorescent dye, and synaptic currents were recorded to determine quantal content of transmission. Along terminals supplying a single muscle fiber, nonuniform release was found: Varicosities closer to the point of origin of the terminal branch released more transmitter than those located more distally. Quantal content was higher for varicosities of the muscle's proximal region (where large EPSPs occur) than for varicosities of the central region (where small EPSPs occur). The probability of transmitter release per synapse is estimated to be greater for the proximal varicosities. At low frequencies of stimulation, quantal content per muscle fiber is two to four times larger in the proximal region. Taken in conjunction with a twofold higher mean input resistance for the proximal muscle fibers, the difference in quantal content can account for a four- to eightfold difference in EPSP amplitude. The observed mean EPSP amplitude is at least eight times larger in the proximal region. We discuss factors contributing to differences in EPSP amplitudes.

Evidence for a vitamin D paracrine system regulating maturation of developing rat lung epithelium

Rat fetal lung is a target tissue for 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25 (OH)2 D3]. We have identified the cells that respond to the hormone and tested the hypothesis that the lung is also a source of 1 alpha,25(OH)2D3. We found that 1) at the end of pregnancy (days 20-21) alveolar type II cells (ATII) bore 1 alpha,25(OH)2D3 receptors and responded to the hormone. Incubating these cells with 10(-9) M 1 alpha,25(OH)2D3 for 48 h stimulated the synthesis (87.3 +/- 9.1%) and release (61.7 +/- 6.1%) of disaturated phosphatidylcholine; 2) EB-1213, a 1 alpha,25(OH)2D3 analogue with low calcemic activity, had similar effects on ATII; 3) neither fetal lung fibroblasts nor neonatal ATII (day 2 postpartum) expressed 1 alpha,25(OH)2D3 receptors; and 4) in contrast, fetal lung fibroblasts taken on days 19-22 of gestation converted [3H]25(OH)D3 to [3H]1 alpha,25(OH)2D3, whereas ATII and skin fibroblasts did not. These findings suggest that 1 alpha,25(OH)2D3 is a local mediator of epithelial-mesenchymal cell interactions in the developing rat lung and that 1 alpha,25(OH)2D3 or EB-1213 might be therapeutically useful in treating the respiratory distress syndrome of premature neonates.

Biochemical and pharmacological characterization of cannabinoid binding sites using [3H]SR141716A

This study describes the binding characteristics of cannabinoid binding sites expressed in rat cerebellar membranes using the tritiated derivative of SR141716A, the newly described cannabinoid receptor antagonist. A single population of high-affinity binding sites (K(D) = 0.59 +/- 0.08 nM; Bmax = 3.86 +/- 0.42 pmol mg-1 of protein) was demonstrated. Kinetic, competition and saturation experiments give similar results in terms of SR141716A affinity. delta 9-tetrahydrocannabinol and the 11-hydroxy derivative competitively inhibited the specific binding of [3H]SR141716A (Ki = 47 +/- 9 and 32 +/- 4 nM, respectively). The cannabinoid agonist WIN55212-2 has a 25-fold lower affinity for [3H]SR141716A than for [3H]WIN55212-2, showing that the two ligands do not recognize the cannabinoid binding site in the same fashion.

Diagnosis, management, and survival of patients with leptomeningeal cancer based on cerebrospinal fluid-flow status

BACKGROUND

The authors assessed cerebrospinal fluid (CSF) flow in patients with carcinomatous meningitis using technetium-99m-DTPA (Tc-99) ventriculography to determine the frequency of flow abnormalities, their reversibility with treatment, and the implications for successful therapy and survival.

METHODS

Technetium-99m-DTPA flow studies were performed in 31 patients after placement of Ommaya reservoirs (Baxter, McGaw Park, IL). Two millicuries of Tc-99 were injected into the reservoir. Planar images of the head and entire spine were obtained after 10 and 30 minutes and after 1, 4, 6, and 24 hours. Follow-up studies were performed for 12 patients whose initial studies were abnormal or who developed complications of therapy.

RESULTS

In 19 of the 31 patients (61%), ventricular-outlet, spinal, or convexity blocks were identified. In 11 of these 19 patients, focal radiotherapy to the site of the block restored normal flow. Survival among patients with initially normal, abnormal but correctable, and abnormal but uncorrectable CSF flow differed significantly (6.9, 13.0, and 0.7 months respectively; P < 0.001). Some patients who were treated intrathecally despite abnormal CSF flow experienced drug-related toxicity.

CONCLUSIONS

Cerebrospinal fluid-flow blocks are common in patients with carcinomatous meningitis and may occur at the skull base, in the spinal canal, and over the convexities. These flow abnormalities often can be corrected with appropriately directed radiotherapy. If untreated, CSF tumor progression (protected site effect), neurotoxicity (high concentration effect), and systemic toxicity (reservoir effect) can occur, resulting in shortened survival and treatment-related morbidity. Therefore, intrathecal chemotherapy should be preceded by a radionuclide flow study and should be delayed if abnormal flow is documented until appropriate radiotherapy reestablishes normal flow.

Synaptic differentiation of a single motor neuron: conjoint definition of transmitter release, presynaptic calcium signals, and ultrastructure

The opener muscle in the walking legs of the crayfish (Procambarus clarkii) is innervated by only one excitatory motor neuron, yet excitatory postsynaptic potentials (EPSPs) of proximal fibers are eightfold larger than those of central muscle fibers at low frequencies of activation, due in large measure to differences in presynaptic properties. We investigated quantal release properties, calcium signals, and ultrastructure of presynaptic terminals to elucidate factors that could account for the physiological differences. Focal macropatch electrodes were placed over individual visualized terminal varicosities to obtain records of quantal contributions to the excitatory junctional current (EJC). At low frequencies of activation, mean quantal content is greater for proximal than for central varicosities. This difference is due to a higher probability of release per synapse, and not to a larger number of active synapses. Recorded varicosities were labeled with fluorescent beads deposited by the electrode. These beads adhered to the muscle fibers, outlining the recorded site for subsequent serial thin sectioning and reconstruction from electron micrographs. Comparisons of structure and function were made for individual varicosities. The number of active zones per terminal surface area and the number of synapses with multiple active zones (complex synapses) were greater in high-output varicosities. Calcium indicators were loaded into proximal and central nerve terminals by axonal injection to compare the relative differences in calcium buildup during stimulation. Presynaptic calcium signals were larger for proximal varicosities than for central varicosities.(ABSTRACT TRUNCATED AT 250 WORDS)

Activity-induced changes in synaptic release sites at the crayfish neuromuscular junction

Crustacean motor axons provide a model in which activity-dependent changes in synaptic physiology and synaptic structure can be concurrently observed in single identifiable neurons. In response to a train of stimulation, crustacean neuromuscular junctions undergo pronounced facilitation of transmitter release. The effects of maintained high-frequency stimulation may persist for at least several hours ("long-term facilitation"). Electrophysiological studies suggest that the number of "active" synapses contributing transmitter quanta at low frequencies of stimulation increases during and after a train of high-frequency stimulation. However, at different terminal recording sites the effect of stimulation varies, and it was observed that not all released quanta produce a voltage change in the postsynaptic muscle cell. Electron microscopic examinations of serial sections from nerve terminals subjected to stimulation were made to determine whether changes in synaptic structure could be correlated with activity-induced long-lasting enhancement of transmission. A procedure was introduced for marking a recorded terminal with fluorescent polystyrene microspheres, which are visible in electron micrographs of the recording site. Crustacean nerve terminals possess a large number of discrete synapses, a small fraction of which have multiple presynaptic "active zones" (dense bodies with clustered synaptic vesicles, thought to represent sites of evoked transmitter release). In terminals previously stimulated, the proportion of synapses with multiple "active zones" is greater than in control unstimulated terminals. Total synaptic vesicle counts and readily releasable vesicles at synapses are not significantly different in previously stimulated terminals and controls. In terminals fixed during stimulation a few synapses show evidence of division in "active zones," and synaptic vesicle counts are lower than in controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Maturational changes induced by 1 alpha,25-dihydroxyvitamin D3 in type II cells from fetal rat lung explants

Specific binding sites for 1 alpha,25 dihydroxyvitamin D3 [1 alpha,25-(OH)2D3] localized to type II pneumocytes have been evidenced in fetal rat lung at the end of gestation, suggesting a role for vitamin D3 in the control of lung maturation. In this study, we describe the morphological changes that occur in lung explants from 18-day-old rat fetuses grown for 1 and 2 days in control conditions and in the presence of 1 alpha,25(OH)2D3 (10(-9) M) or dexamethasone (10(-7) M). Point counting and planimetric measurements on light and electron micrographs show that 1 alpha,25-(OH)2D3 1) dramatically decreases the mean glycogen content of type II cell profiles between days 1 and 2 of the culture, suggesting an acceleration of the glycogenolytic processes normally occurring at that stage and 2) does not change the intracellular osmiophilic lamellar body (OLB) content of cell profiles, but increases the amount of intraluminal surfactant by 126% when expressed as surfactant clusters surface area/section surface area and by 129% when expressed on a per cell basis, suggesting a stimulation of surfactant synthesis and secretion. By contrast, dexamethasone increases the mean intracellular OLB content of type II cell profiles by 306% and decreases the relative surface area of secreted material by 53 and 73%. In conclusion, 1 alpha,25(OH)2D3 accelerates the physiological maturation of fetal rat type II pneumocytes and could represent a key factor for the onset of normal lung function at birth.

[Fractures of the clavicle in neonates]

One hundred and twenty-five newborn infants (6.26%) with clavicular fractures were detected among 1995 neonates seen at the maternity hospital over a period of 16 months. Physical and only exceptionally X-ray examinations were performed. Clinical picture with the subsequent occurrence of callus were pathognomonic signs. The following parameters were taken into consideration for this study: infant's birth weight, sex, risk factors, way of delivery, delivery line, Apgar score, seasonal distribution and complications. Newborn infants with clavicle fracture were infants whose weight was more than 3500 g (3763.36 +/- 360.58 g, chi 2 = 65.605, P < 0.05), most frequently from mothers with the second childbirth (48.8%), babies born in a normal and natural way (58.4%), and in 71. 33% of the cases with some risk factors and Apgar score more than 7. One thousand seven hundred and forty-two out of a total of 1995 neonates had birth weight less than 4000 g and in 92 of these 1742 infants (5.29%) clavicular fractures were found, while in 253 newborn infants with birth weight more than 4000 g, 33 neonates (13.05%) had clavicular fractures. Clavicle fractures were more frequently found among the infants with birth weight more than 4000 g (P < 0.05). Three out of a total number of infants had paresis plexus brachialis, two of which belonged to the group of children with clavicle fractures. This study suggests that the approach to the childbirth conducting should be changed, so that the percentage of clavicle fractures can be reduced or noticed in time by help of more frequent and systematic clinical examinations.(ABSTRACT TRUNCATED AT 250 WORDS)

Variation in terminal morphology and presynaptic inhibition at crustacean neuromuscular junctions

Synaptic terminals of excitatory and inhibitory neurons supplying muscle fibers in leg muscles of crabs (Pachygrapsus crassipes and Hyas areneus) were investigated with light and electron microscopy. Terminals responsible for large excitatory postsynaptic potentials (EPSPs) at low frequencies of activation had a compact configuration with clusters of terminal boutons radiating from the main axon branch. Terminals responsible for small EPSPs had a more diffuse organization, with boutons often arranged in series along thin axon branches. Inhibitory neurons, when activated, produced both presynaptic and postsynaptic inhibitory effects, with the former being more potent at low frequencies of activation. Presynaptic inhibition was variable in magnitude but was generally strong in fibers with large EPSPs. Representative terminals from regions of strong and weak presynaptic inhibition were identified by activity-dependent uptake of horseradish peroxidase, serially sectioned, and reconstructed from electron micrographs. Both regions were found to contain axo-axonal synapses from inhibitory to excitatory terminals, with a larger number in the region of strong presynaptic inhibition. In addition, axo-axonal synapses were more uniformly distributed in the latter region. The number of inhibitory presynaptic dense bars (active zones) was somewhat higher in the region of weak inhibition, but larger individual dense bars occurred in the region of strong inhibition. Possible factors contributing to the differences in strength of inhibition include: (1) morphology and electrical properties of terminals; and (2) high probability of transmission at a relatively small number of inhibitory synapses during low frequency activation in the region of strong inhibition.

Oral rehydration therapy: studies on potassium balance

The clinical response and changes in potassium balance were studied during oral rehydration therapy (ORT) with a solution containing 20 mmol potassium per litre in well-nourished and malnourished infants of 3 to 15 months of age as well as in neonates and young infants less than 2 months old (range 5-60 days). All infants were successfully rehydrated orally. The potassium intake considerably exceeded the potassium output in all groups during the entire rehydration period. The stool and urine potassium output were about the same in the 3 groups of patients. The retention of potassium increased during ORT in all groups at about the same rate. The study thus demonstrates that an oral rehydration solution (ORS) containing 20 mmol potassium per litre provides enough potassium to all patients. An increase in the potassium concentration of the ORT is therefore not recommended.

1,25-dihydroxyvitamin D3 receptors in rat lung during the perinatal period: regulation and immunohistochemical localization

We have previously reported that in contrast to what has been described in adult lung, 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] has specific binding sites in rat fetal lung at the end of gestation, and it stimulates in vitro the phospholipid biosynthesis and surfactant release from fetal rat type II pneumocytes. In the present study an immunohistochemical technique using a rat monoclonal antibody (9A7 gamma) and binding studies were carried out on fresh lung tissues from fetal and newborn rats during the perinatal period to identify the cell(s) directly responsive to 1,25-(OH)2D3 in fetal lung and to look for a down-regulation of the 1,25-(OH)2D3 receptors in the perinatal period. We also searched for a regulation of 1,25-(OH)2D3 binding to fetal lung by 1,25-(OH)2D3 itself and by factors known to affect lung maturation or be involved in parturition. Our results suggest that 1) fetal type II pneumocytes are target cells for 1,25-(OH)2D3; 2) a physiological down-regulation of the 1,25-(OH)2D3 receptors in rat lung occurs in the perinatal period, starting a few hours before birth and lasting at least up to the fifth day of life; and 3) the capacity of rat fetal lung to bind 1,25-(OH)2D3 can be modulated in vitro by different hormones; a small inhibitory effect is observed with oxytocin (100 microU/ml), while PRL (10(-8) M), T4 (10(-6)-10(-10) M), 1,25-(OH)2D3 (10(-9)-10(-10) M), and, to a lesser extent, dexamethasone (10(-7) M) induce a 2- to 4-fold increase in the number of 1,25-(OH)2D3 receptors without altering the binding affinity of receptor for 1,25-(OH)2D3.

Relationships among surfactant fraction lipids, proteins and biophysical properties in the developing rat lung

Lung development is associated with increases in specific phospholipids and proteins that function as critical pulmonary surfactant components. Attempts to characterize the pattern of surfactant development in fetal rat lungs have been hampered by the lack of a micromethod which will permit quantitative isolation of surface active components from small tissue specimens. As part of studies designed to elucidate the metabolic regulation of lung development in the rat, we developed sucrose density gradient centrifugation procedures to separate pulmonary phospholipids and proteins into a presumed surfactant (S) fraction and a residual (R) fraction. Electron microscopy of S pellets from mature fetuses identified predominant lamellar bodies and minimal contamination; incubation with 5 mM CaCl2 induced the appearance of tubular myelin figures, implying functional potential. This was confirmed by demonstrating low surface tension (less than 1 dyn/cm) in S, but not R, fractions at term gestation (21.5 days) and in 1-day-old neonatal lung isolates, based on dynamic measurements using the oscillating bubble technique. Surface activity was also high in the S pellets from fetuses at 20.5 days of gestation; however, at 19.5 days, minimum surface tension values of at least 19 dyne/cm were seen. These results correlated directly with biochemical analyses which indicated striking increases in three surfactant-associated proteins (SP-A, SP-B, and SP-C) after 19.5 days of gestation; a finding in agreement with previously reported data on the developmental increase of disaturated phosphatidylcholine in fetal rat lung. We conclude that isolation of S fraction components is valuable for demonstrating maturation of the fetal rat lung and may provide a useful tool for the study of regulatory mechanisms influencing surfactant production and function.

Effects of the antiglucocorticoid RU 486 on the initiation of ultrastructural type-II cell differentiation in fetal rat lung

The possible early role of endogenous glucocorticosteroids on the further ultra-structural development of the fetal rat lung epithelium was investigated in vitro using a potent antiglucocorticoid drug, RU 486. Lung primordia were explanted on day 13 of gestation and cultured for 4-6 days in the presence of fetal calf serum, with or without RU 486 in excess. The results obtained show that osmiophilic lamellar bodies specific for morphologically differentiated type-II cells did appear in a number of epithelial cells, even though the glucocorticosteroids possibly present in the culture medium, or transferred at explantation were antagonized by RU 486. The number of lamellar bodies stored in these pneumocytes was not different from that in controls. In contrast, their total surface area per cell profile was transiently decreased. Taken together the reported data strongly suggest that endogenous glucocorticosteroids are not necessary for the initiation of type-II cell differentiation.

1,25(OH)2D3 stimulates phospholipid biosynthesis and surfactant release in fetal rat lung explants

Lung tissue from 18-day-old rat fetuses was cultured in the presence of 1,25-dihydroxyvitamin D3 - 1,25(OH)2D3 - (10(-9) M) and dexamethasone (10(-7) M) for 48 h. 1,25(OH)2D3 increased the lung content in phospholipids more specifically related to lung surfactant, phosphatidylcholine and phosphatidylglycerol. This increase was similar to that observed with dexamethasone. In addition, unlike dexamethasone, 1,25(OH)2D3 stimulated the surfactant release into luminal spaces, as evidenced by light and electron microscopy. Thus, vitamin D3 might represent an additional factor controlling fetal lung maturation by stimulating phospholipid synthesis and surfactant release from type II cells.

Effects of the antiglucocorticoid RU 486 on the maturation of fetal rat lung surfactant

The role of endogenous glucocorticoids in the control of surfactant system maturation was investigated in the fetal rat using an antiglucocorticoid molecule synthesized by Roussel-UCLAF, RU 486. The drug was administered to the mother from day 16 of gestation on. In a preliminary step, the transplacental transfer of RU 486 and its antiglucocorticoid effects on fetal target tissues were verified by evidencing RU 486-receptor complexes in fetal liver and lung, by measuring liver glycogen content, and by evaluating fetal blood corticosterone. The maturational state of fetal lungs was assessed biochemically on days 19, 20, and 21 of gestation by measuring their glycogen content, the phospholipid content of whole lung tissue and isolated surfactant fraction, and the incorporation of [methyl-3H]choline into DSPC. Morphological development was studied by analyzing electron micrographs of type II cells. The measured parameters clearly indicated a slowing of maturational processes in lungs of fetuses from RU 486-treated mothers, thereby demonstrating that endogenous glucocorticoids are actually involved in the control of lung maturation. In addition, the obtained results showed that endogenous corticosteroids specifically acted on the surfactant system of the fetal lung.

Synaptic restructuring during long-term facilitation at the crayfish neuromuscular junction

Long-term facilitation was induced by 20-Hz stimulation of the motor axon innervating the opener muscle of the crayfish, Procambarus clarkii. Excitatory postsynaptic potentials remained potentiated for several hours after stimulation. Structural correlates of potentiation were sought. Nerve terminals of the motor axon were fixed for electron microscopy in unstimulated preparations (controls), and during and after 20-Hz stimulation. Synapses were reconstructed from micrographs obtained from serial sections. Synaptic contact area and the number of vesicles at the presynaptic membrane did not change after 20-Hz stimulation, but the latter decreased during stimulation. Presynaptic dense bars ("active zones") decreased in number during and increased after stimulation, while perforated synapses increased after stimulation. Modification of presynaptic structures occurs rapidly and may be linked to long-lasting changes in quantal content of transmission.

Salt and water homeostasis during oral rehydration therapy in neonates and young infants with acute diarrhoea. II. Rehydration with a solution containing 90 mmol sodium per litre (ORS90)

The clinical response and changes in water and salt homeostasis were studied during oral rehydration therapy (ORT) with a solution containing 90 mmol sodium per 1 (ORS90) in 9 infants less than 2 months old (range 2-60 days). Two infants were still dehydrated 36 hours after starting ORT and were excluded from the study. Fluid was retained more rapidly and also to a larger extent than in infants of the same age treated with a solution with a sodium concentration of 60 mmol/l (ORS60). The stool sodium output was higher than that found previously in infants of the same age treated with ORS60. We conclude that during ORT the gut plays an active role in the regulation of salt homeostasis. When the sodium intake is high the percentage of sodium remaining unabsorbed is higher than when the intake is low. This mechanism reduces the risk of hypernatremia in young infants treated with ORS90. The study thus demonstrates that ORS90 is effective and also seems to be safe in the treatment of neonates and young infants with dehydration secondary to diarrhoea if fluid intake is kept around 200 ml/kg/day during the rehydration period.

Definitive radiation treatment for early stage carcinoma of the soft palate and uvula: the indications for iridium 192 implantation

From 1971 to 1984 59 T1 and T2 carcinomas of the soft palate and uvula were treated definitively by irradiation at the Henri Mondor hospital. Included are ten patients previously irradiated to the oropharyngeal area for either a carcinoma of the soft palate or another malignancy. Sixteen patients were treated by external irradiation alone, 14 by Iridium 192 implantation, and 29 by a combination of the two. Two techniques of implantation were used: the guide gutter technique (33 patients) and the plastic tube technique (10 patients). Clinically negative neck nodes (51/59) either received prophylactic telecobalt therapy (39/51) or were surveilled (12/51). Clinically involved nodes (8/59) were managed either by external irradiation alone (4/8) or combined with neck dissection (4/8). Local failure was 25% (4/16) after exclusive telecobalt therapy, 18% (5/19) after combined telecobalt therapy and implantation, and 0% (0/14) after Iridium 192 implantation alone. No local failures were seen with the plastic tube technique (0/10) as compared to 15% (5/33) for guide gutters. Only two nodal failures were observed (2/59: 3%). Crude 5-year disease-free survival was 33%. Severe complications were limited to one osteonecrosis, one soft tissue necrosis, and one partial palatal incompetence. Salivary impairment was reduced when implantation was used for part or all of the treatment. We recommend 45 Gy external radiation followed by 30 Gy from Iridium 192 implantation using the plastic tube method unless there has been prior oropharyngeal irradiation, in which case we give 60 Gy from implantation alone. For clinically negative neck nodes, we recommend 45 Gy prophylactic external neck irradiation. For clinically positive lymph nodes, this should be followed by either a 25 to 30 Gy boost to the involved nodes or a neck dissection.

Focal labeling of axonal terminals with active synapses recorded by an extracellular macro-patch electrode

A technique to label active synaptic terminals, whose electrophysiology had been monitored by a macro-patch electrode, was developed for a crustacean neuromuscular preparation. The active synaptic terminals were labeled by release-dependent uptake of horseradish peroxidase (HRP) into synaptic vesicles. The focal labeling technique involved the following steps: (1) locating a site where evoked synaptic currents could be recorded at a subset of neuromuscular synapses by a macro-patch electrode; (2) reducing synaptic transmission by bathing the preparation in a solution containing low [Ca2+] and high [Mg2+]; (3) introducing HRP as an extracellular marker into the solution bathing the preparation; (4) restoring synaptic release focally by ejection of a solution containing Ca2+ from the macro-patch electrode. The muscle fibre with labeled synapses was fixed for electron microscopy and processed for HRP histochemistry. The distribution of HRP-labeled vesicles was documented by electron microscopy and semi-serial sectioning. A significant increase in labeled vesicles was found within a maximum radius of 10-15 micron from the lumen of the macro-path electrode. This maximum radius of labeling set an upper limit to the number of active synapses recorded by the macro-patch electrode.

Oral rehydration therapy in neonates and young infants with infectious diarrhoea

The clinical response and changes in water and salt homeostasis during ORT was studied in 15 infants less than 2 months old (range 2-50 days) with acute diarrhoea. Eight patients were neonates and 7 were 1-2 months old. The oral rehydration solution contained 60 mmol sodium per litre. All patients except one were successfully rehydrated. The fluid retention was significantly higher in neonates and young infants than in infants above 3 months of age treated in the same way. One patient in the group of neonates who had a normal sodium level on admission developed hypernatremia with a sodium level of 162 mmol/l 36 hours after the start of ORT. The urinary sodium excretion was lower in the neonates than in the young infants. The results show that neonates and young infants have a lower capacity than older infants to excrete water and salt and therefore run a great risk of developing fluid and salt retention during ORT. The risk is most pronounced in neonates who, due to immaturity of the renal function, are unable to excrete excess fluid and salt.

Lung maturation in the hyperinsulinemic rat fetus

Hyperinsulinemic rat fetuses were obtained either by repeated in utero injections of long-acting insulin (resulting in fetal hypoglycemia) or by chronically infusing intravenous glucose to the mother (resulting in fetal hyperglycemia). Fetuses were examined at term. In insulin-injected fetuses (n = 15), surfactant (S) fraction phosphatidylcholine (PC) and disaturated phosphatidylcholine (DSPC) were significantly decreased (3.6 +/- 0.1 nmol Pi/mg tissue; p less than 0.001 and 2.8 +/- 0.1 nmol/mg; p less than 0.025, respectively) as compared with their saline-injected controls (4.8 +/- 0.2 and 3.3 +/- 0.1 nmol/mg, respectively, n = 19). However, residual (R) fraction was unchanged, and there was no difference in whole-lung phospholipids (combined S and R fractions). These results are consistent with morphological data showing a lower lamellar body area per type II cell profile in insulin-injected fetuses as compared with their controls [1.41 +/- 0.13 micron 2 (n = 72) versus 1.99 +/- 0.14 micron 2 (n = 129) p less than 0.01]. Glycogen content was slightly higher in insulin-injected fetuses (18.5 +/- 1.0 micrograms/mg, n = 17) than in their controls (15.1 +/- 0.8 micrograms/mg, n = 18; p less than 0.05). In the second model, changes in S fraction PC and DSPC were similar to those observed after insulin-injections: 4.3 +/- 0.25 and 3.4 +/- 0.2 nmol Pi/mg in fetuses of glucose-infused rats (n = 10) versus 5.7 +/- 0.45 and 4.3 +/- 0.3 nmol Pi/mg, respectively, in controls (n = 10, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Optimization of fetal lung organ culture for surfactant biosynthesis

Lung organ culture has been a widely used system for studying differentiation and maturation of alveolar epithelium through various culture conditions. The purpose of this work was to carefully characterize in vitro lung biochemical differentiation through isolation of surfactant fraction from tissue and to search for optimal culture conditions. Fetal rat lung was explanted on the 18th gestational day for studying glycogen storage, and on the 20th gestational day for studying surfactant accretion, and cultivated for 48 h. Morphologic differentiation was studied by electron microscopy on tissue explanted on the 17th or 18th gestational days and cultivated for various times. Glycogen storage was greater on fluid medium, although less than occurring in vivo. Cellular integrity and surfactant accumulation were maximal on a semisolid medium containing 0.5% agar. Use of O2-CO2 instead of air-CO2 for gassing the explants slightly decreased phospholipid accumulation. Among media used in previous lung culture studies, Waymouth MB 752/1 was the only one to allow net glycogen accumulation in vitro. The most favorable media for surfactant phospholipid accretion were Waymouth MB 752/1, Eagle's minimum essential and its Dulbecco's modification, CMRL 1066, and NCTC 109. They allowed a 12- to 14-fold increase of surfactant fraction phospholipids in vitro, which is similar to the increase occurring in vivo during the same period. Ham's F10 and F12 media allowed a six fold increase. RPMI 1640 and medium 199 (M199) allowed only a three fold increase. Phospholipid concentration in nonsurfactant fraction only doubled during culture, and differences between various media were much less marked. DNA concentration changed little during culture. Morphologic differentiation of epithelial cells was advanced as compared with in vivo timing in a medium allowing maximal surfactant accretion (Waymouth MB 752/1) but not in a medium allowing low surfactant increase (RPMI 1640). The possible role of compositional differences between media is discussed.

The indications for total cutaneous electron beam radiation therapy of mycosis fungoides

From 1977 to 1984, we treated 34 patients with mycosis fungoides and 9 patients with B cutaneous lymphomas. Eighteen patients with mycosis fungoides were treated with total skin electron irradiation (TSEI) and had a minimum follow-up of 15 months (range 15 months to 7 years). The lowest electron energy of the linear accelerator was 8 MeV therefore we placed a plexiglas screen between the patient and the machine; the resulting electron energy was 4 MeV. The total dose was 30 Gy delivered in 12 fractions over 40 days. There were 8 males and 10 females. The median age was 48 years (ranging from 13 to 78 years). All patients were staged as follows: Stage A = superficial lesions covering less than 50% of the body surface; Stage B = superficial lesions covering more than 50% of the body surface; Stage C = tumors involving the skin, lymph nodes and/or visceral organs. Five patients with Stage A (5/5) and 5 patients with Stage B (5/5) had a complete remission, 1 stage A patient relapsed 6 months after completion of treatment. All the Stage B patients recurred between 3 and 15 months. The recurrences were localized to the skin and were well controlled with topical nitrogen mustard or puvatherapy. Among the Stage C patients, 3 did not respond to treatment and died of their disease; the remaining 5 patients achieved complete remission but they all relapsed from 2 to 9 months following completion of treatment. The median follow-up was 32 months and the average time for relapse was 6.5 months. All relapses except one (15 months) occurred within the first year. We feel that total skin electron irradiation is indicated in Stage A and B patients. However, we feel Stage C patients should receive TSEI for palliative purposes only.

The past and future of conservative treatment of breast cancer

Since 1961 more than 1,200 patients with breast cancer were treated conservatively at the Institut Gustave Roussy (Villejuif) and, since 1970, at the Hôpital Henri Mondor (Créteil). This group included approximately 25% T1 tumors, 55% T2 tumors, and 20% T3 tumors. All of these patients were staged, according to the U.I.C.C. Tumor Classification System. This paper presents the results of treatment of 330 patients who were followed for a minimum of 10 years and 59 patients who were followed for a minimum of 15 years. We also present our most recent protocol, which has been in use since 1983.

Radiation therapy for carcinoma of the pinna using iridium 192 wires: a series of 70 patients

From January 1970 to November 1982, 70 patients with carcinoma of the pinna were treated by interstitial irradiation. An afterloading technique with Iridium 192 wires was used. One patient recurred and had a total pinnectomy followed by 60 Gy external radiation. This patient was alive without evidence of disease at 134 months. Three patients who had tumors greater than 4 cm in size at presentation developed late necrosis which required subsequent total pinnectomy. Cosmetic results were assessed in 55 patients and were good with few late sequelae (in 78% of cases (36/46) when the tumor measured less than 4 cm, but only in 1/9 when the tumor measured more than 4 cm). We advocate interstitial Iridium 192 irradiation for treatment of pinna tumors smaller than 4 cm. None of 39 patients with squamous cell carcinoma had biopsy proven cervical lymph node metastasis at the time of diagnosis. Four patients with squamous cell carcinoma (4/39: 10%) later developed a regional nodal metastasis after treatment of the pinna. All four relapsed in the parotid region and were managed by partial parotidectomy and neck dissection followed by external irradiation. One of these four patients died from uncontrolled cervical node disease. In our opinion, when regular follow-up is dependable, it is reasonable to save treatment of the cervical nodes for those patients who relapse with involved metastatic cervical nodes.

Morphological transformation of synaptic terminals of a phasic motoneuron by long-term tonic stimulation

In vivo stimulation of a relatively "silent" phasic crayfish motoneuron changes the ultrastructure of its synaptic terminals to a more tonic phenotype. The closer muscle of the crayfish claw is supplied by only 2 excitatory motoneurons, one of which is phasic and the other tonic. The ultrastructures of conditioned phasic, unconditioned phasic, and tonic motor terminals were compared. The terminals of the tonic motor axon were larger in cross-sectional area, had larger mitochondria, greater synaptic contact area, and were more varicose than unconditioned phasic terminals. Following long-term tonic stimulation of the phasic axon, its terminals became more varicose, mitochondrial cross-sectional area more than doubled, and synapses and mitochondria came into closer proximity, although mean terminal cross-sectional area did not change. Thus, the conditioned phasic terminals became more similar to those of the tonic motor axon. These changes in ultrastructure correlate with, and may be causally linked to, previously reported changes in neuromuscular synaptic physiology produced by in vivo tonic stimulation of this motoneuron. We conclude that the ongoing level of impulse activity can affect the ultrastructural differentiation of synaptic terminals and synapses of the phasic motoneuron.

Oral rehydration therapy in malnourished infants with infectious diarrhoea

The clinical response and changes in water and salt homeostasis was studied for 36 hours during oral rehydration therapy with a rehydration solution containing 60 mmol sodium/l (ORS60) in 14 malnourished 3- to 15-month-old Turkish infants with acute infectious diarrhoea. All patients were successfully rehydrated with this treatment. Sodium was efficiently absorbed from the gut and water balance was rapidly restored. Because of excess fluid retention following the initial rehydration period about 50% of the patients became oedematous. Urine volume and urinary sodium excretion were found to be much lower than in well-nourished patients of the same age with acute diarrhoea who were treated in the same way. In all of the malnourished infants the serum sodium level remained within the normal range during treatment. The results show that malnourished infants retain much more fluid and sodium than infants who are in a normal nutritional state. Excessive retention of water and salt seem to be due to an inability of the kidneys to control sodium and fluid homeostasis while orally administered sodium and fluid are being absorbed from the gut. The results show that ORT is safe and efficient in the treatment of malnourished infants with acute diarrhoea. But since these infants run a high risk of developing a severe retention of fluid and salt, and consequently may develop circulatory failure due to hypervolaemia during oral rehydration therapy, it is important to carefully monitor the volume of fluid that is given.

Maturation of fetal rat lung in diabetic pregnancies of graduated severity

Biochemical and morphologic maturation of fetal rat lung was studied in pregnant, diabetic rats with different levels of glucose intolerance (sub-, mildly, and severely diabetic). Fetuses were almost normoglycemic and hyperinsulinemic in subdiabetic rats, both hyperglycemic and hyperinsulinemic in mildly diabetic rats, and hyperglycemic but hypoinsulinemic in severely diabetic rats. A similar delay in type II pneumocyte differentiation and a similar decrease of disaturated phosphatidylcholine (DSPC) content in lung tissue and broncho-alveolar material recovered by lung lavage occurred in the fetuses of the three diabetic groups, independently of the severity of diabetes. Phosphatidylglycerol (PG) was decreased in fetuses from severely diabetic rats only. DSPC appeared specifically affected in fetuses of sub- and mildly diabetic groups, whereas in those of severely diabetic groups, DSPC alterations accompanied a variety of abnormalities including whole lung hypoplasia and hypotrophy and decreases of sphingomyelin, unsaturated PC, and lysoPC. The mechanisms leading to abnormal lung development could therefore be different in fetuses of sub- and mildly diabetic rats on one hand and fetuses of severely diabetic rats on the other. Since hyperinsulinemia was the prominent feature of fetal "milieu intérieur" in subdiabetic rats, this study presents arguments gained from in vivo experiments for an implication of hyperinsulinemia in lung developmental retardation due to maternal diabetes. However, the decrease of PG seems to depend on increased blood glucose level in itself. Diminished lung glycogen breakdown and decreased lung triglyceride content, more pronounced in fetuses of sub- and mildly diabetic rats than in those of severely diabetic rats, suggest that in the former, the decrease of DSPC biosynthesis could be due to decreased availability of substrates because of abnormal glycogen utilization. Fetuses from sub- and mildly diabetic rats constitute experimental models most closely resembling the human fetus of the diabetic mother with respect to circulating glucose and insulin. They appear therefore more adequate for elucidating the mechanisms of abnormal lung development in the diabetic pregnancy. In contrast, fetuses from severely diabetic rats associate very high blood glucose levels and hypoinsulinemia, which are features closer to those of adult diabetic subjects than to those of the human fetus of the diabetic mother.

Oral rehydration therapy in infectious diarrhoea. Comparison of rehydration solutions with 60 and 90 mmol sodium per litre

The clinical response and changes in water and salt homeostasis as judged from serum sodium levels, salt and water retention and renal handling of sodium was studied during 36 hours following the start of oral rehydration therapy (ORT) with a solution containing 60 mmol Na/l (ORS60) in 17 well-nourished, moderately dehydrated Turkish infants aged 3 to 15 months who had acute infectious diarrhoea (7 with rotavirus, 3 with enteropathogenic E. coli 0 111: B 84, and one with enteropathogenic E. coli 0 125: B 15, one with salmonella and 5 of unknown etiology. In the successfully treated patients sodium and water balance was normalized within 36 hours. In the cases with hypernatremic dehydration the serum sodium concentration rapidly became normal. The results were compared with those obtained in a previous study of the same type of patients who were rehydrated with a solution containing 90 mmol Na/l (ORS90). Although retention was considered to be satisfactory after ORS60 it was less than after ORS90. The changes in the fractionary urinary sodium excretion and the potassium sodium quotient in the urine indicated a less rapid normalization after ORS60 than after ORS90.

Unsuccessful oral rehydration therapy in an infant with enteropathogenic E. coli diarrhoea. Studies of fluid and electrolyte homeostasis

A 4-month-old male infant with severe hyponatremic dehydration due to an enteropathogenic E. coli O125: B15-induced diarrhoea had continued very high stool fluid output with a very elevated sodium concentration after hospitalization and the institution of oral rehydration therapy (ORT). Thirty-six hours after start of ORT intravenous therapy was required. The results of studies of fluid and salt homeostasis in this patient have been compared with those obtained in 3 other patients who had acute diarrhoea of the same severity but caused by another strain of enteropathogenic E. coli (O111:B14) and who were successfully treated with ORT. On ORT the patient with treatment failure had a stool volume which was almost 8 times larger and a stool sodium output which was about 5 times higher than in the successfully treated patients. During the 36-hour-period of ORT fluid losses were about the same as the fluid intake. The results as regards urinary fractional sodium excretion and the urinary potassium/sodium quotient indicate that the severe sodium depletion which was present on admission in the unsuccessfully treated patient persisted during ORT. The reason for ORT failure may be that the infectious E. coli strain had bacilli-adherent qualities that cause damage of microvilli.

Colonic water and electrolyte transport in young and adult rats

The development of colonic water and electrolyte transport was studied in rats. The colon of 20-day-old (young) and 40-day-old (adult) rats was perfused with either a hypotonic (200 mosmol/L) or a hypertonic (450 mosmol/L) solution. The solutions had identical electrolyte contents. Polyethylene glycol was used as a marker of water absorption. Na,K-Adenosine triphosphatase (Na,K-ATPase) activity was determined in nonperfused colonic segments in 10- to 40-day-old rats. Water absorption was always higher in young rats than in adult rats. In the young rats but not in the adult rats increased osmotic pressure of the luminal fluid resulted in a significant decrease in water absorption. The secretion of K was observed only in adult rats. Na,K-ATPase activity increased significantly from 10 to 20 and from 20 to 40 days of age. The results imply that the immature colon has higher water conductivity and low active electrolyte transport.

Axoaxonal synapse location and consequences for presynaptic inhibition in crustacean motor axon terminals

Serial sections were made of several excitatory nerve terminals in the stretcher muscle of the spider crab, Hyas areneus , to document locations of inhibitory axoaxonal synapses responsible for physiologically powerful presynaptic inhibition. The excitatory terminals are varicose, often with small side branches joined to the main terminal by thin bottlenecks . Axoaxonal synapses occur predominantly on the varicosities, both primary and secondary, with a smaller number on bottlenecks . The distribution is often clustered at specific locations of the excitatory terminal. An electrical model was employed to ascertain the effectiveness of axoaxonal synapses at different locations on the terminal. The model plotted the potential distribution along the terminal with or without a synaptic conductance equivalent to one quantal unit of inhibitory transmitter action. It was assumed from recent work that terminal varicosities are not completely invaded by an action potential. The model predicts that large drops in potentials originating in the main axon occur in the terminals during inhibitory transmitter action, with the largest total drop produced by axoaxonal synapses on the terminal varicosities. The effectiveness of inhibitory action is critically dependent on the dimensions and internal resistance of the bottlenecks . Thus, the geometrical features of the excitatory terminal appear to play a key role in effectiveness of presynaptic inhibition.

Salt and water homeostasis during oral rehydration therapy

Changes in sodium balance and urinary and stool output during orally administered rehydration therapy were studied in 22 well-nourished Turkish infants, aged 2 to 13 months, with acute diarrhea mainly of viral origin. The infants randomly received a rehydration solution containing either 90 mmol Na/L (ORS90) or 40 mmol Na/L (ORS40). Slight transient hypernatremia was noted in a few infants receiving ORS90, and slight transient hyponatremia in a few infants receiving ORS40. In both groups, sodium balance increased most rapidly during the first 12 hours of rehydration, and then more slowly because of increased urinary as well as stool sodium output. Sodium balance was always more positive after ORS90 than after ORS40, but the difference did not change much from 12 to 36 hours after therapy was started. Changes in fractional sodium excretion, urinary K/Na quotient, and urinary aldosterone-creatinine quotient were used as indexes of changes in sodium balance. All values were interpreted to indicate that the sodium deficit on admission was corrected within 12 to 18 hours after ORS90 and, in most cases, after 24 to 36 hours after ORS40. Both groups of infants responded well to orally administered rehydration therapy from the clinical viewpoint.

Different mechanisms of mitral regurgitation in acute and chronic forms of coronary heart disease

Contradictory two-dimensional echocardiographic findings have been reported in relation to the role of prolapse of the mitral valve and lack of systolic leaflet coaptation in mitral regurgitation secondary to coronary heart disease. A prospective study of 22 patients with chronic coronary heart disease and mitral regurgitation showed the following: Inferior akinesia was detected in 14 (64%), fibrosis of the postero-medial papillary muscle in 10 (45%), and prolapse of the mitral valve in nine (41%). A combination of the three signs was seen in six patients (27%). Lack of systolic leaflet coaptation was seen in only two patients, both with anterior myocardial infarction. When these results are compared with those reported in the literature, it is apparent that in acute coronary heart disease, lack of leaflet coaptation is frequently visualized (P less than 0.01) and fibrosis of the postero-medial papillary muscle and prolapse of the mitral valve are lacking (P less than 0.01). A unitary explanation of all forms of mitral regurgitation in coronary heart disease is misleading; mechanisms of mitral regurgitation in coronary heart disease depend on the clinical presentation--acute or chronic, the site of infarction, and the presence of cardiac dilatation.

Ultrastructure of synapses with different transmitter-releasing characteristics on motor axon terminals of a crab, Hyas areneas

Synaptic terminals on branches of an excitatory motor axon in a spider crab (Hyas areneas) were examined by electron microscopy to determine whether differences in size, structure, and number of synapses could be correlated with differences in transmitter release. Terminals releasing relatively large amounts of transmitter during low frequencies of nerve impulses ("high-output" terminals) had larger synapses, more prominent presynaptic dense bodies (active zones), and fewer synapses per unit length than terminals releasing relatively small amounts of transmitter ("low-output" terminals). Neither the difference in synaptic area, nor the quantitative differences in the active zones, were sufficient in themselves to explain the difference in synaptic efficacy, and it is postulated that a non-linear relationship may exist between structural features of the synapse and release of transmitter by a nerve impulse, and that differences other than those apparent from the ultrastructure could be involved. Greater facilitation at low-output terminals with high frequencies of nerve impulses may be due to greater reserves of "immediately available" transmitter, and to recruitment or activation of more individual synaptic contacts.

Changes in the cellular environment of differentiating type II pneumocytes. Quantitative study in the perinatal rat lung

The changes occurring in the cellular environment of differentiating type II pneumocytes have been studied using the perinatal rat lung as a model. The various cellular types in contact with type II pneumocytes during late fetal and neonatal period have been identified. The percentage of type II cells in contact with each cellular type has been calculated, and the extent of the contact areas has been measured. During the studied period, type II pneumocytes are in contact with other epithelial cells (type I or type II pneumocytes) on their lateral sides. On their basal side, they are facing lipid loaded fibroblasts and endothelial cells of the capillary walls. The results of the measurements show that from day 19 of gestation on, the contact area between type II pneumocytes and other epithelial cells decreases, whereas the luminal and especially the basal sides increase. On day 19, the whole basal side of type II pneumocytes in lined by lipofibroblasts. As maturation proceeds thereafter, contact is gradually made with endothelial cells. But the extent of these contacts remains always smaller than the contacts between type Ii pneumocytes and lipofibroblasts. The developmental significance of these results is discussed.

Lung catecholamines and cyclic nucleotides during perinatal development in the rat. Possible relationships with biochemical and morphological differentiation

In this study, we investigated in parallel the evolution of endogenous catecholamine and cyclic nucleotide levels in lung tissue in the course of normal fetal development of the rat from day 17 of gestation to day 10 postpartum; the findings were correlated with the successive stages of lung differentiation. These were assessed morphologically by electron microscopy, and biochemically by measuring the levels of the main lung tissue phospholipids and studying their fatty acid composition. Dopamine levels were low and always remained under 5 ng/g of wet tissue. Nevertheless, slight rises were observed between days 17 and 19 of gestation (1.8 and 2.78 ng/g, respectively) and between days 21 of gestation and birth (2.56 and 4.25 ng/g, respectively). These changes were significant (P less than 0.05). Norepinephrine (NE) levels first decreased by about 50% between days 17 and 19 of gestation (7.34 and 3.88 ng/g, respectively), (P less than 0.01) and then rose sharply about 4 times until birth (17.24 +/- 3.90 ng/g), and more slowly from then on. On day 10 postpartum, the mean NE level was 34.31 +/- 3.28 ng/g. The levels of the two cyclic nucleotides [cyclic adenosine 3':5'-monophosphate and cyclic guanosine 5'-monophosphate (cGMP)] were quite high on day 17 and remained so until day 19 (cAMP = 220 pmoles /g; cGMP = 20 pmoles/g). From day 19 until day 21, the levels of the two nucleotides decreased (cAMP = 140 pmoles/g; cGMP = 8 pmoles/g; P less than 0.05). During this period, the decrease in cGMP level was about twice that of cAMP. During the last day of gestation, the cAMP level was still decreasing, whereas cGMP was increasing. After birth, the levels of the two cyclic nucleotides rapidly increased to day 5. Between days 5 and 10 postpartum, no significant changes were observed in either cAMP or cGMP levels. The time course of the variations reported suggests that they are related to the maturation processes of lung assessed on the basis of morphological and biochemical criteria. On day 19 of gestation, when the first lamellar bodies appear, large changes occur in the evolution of NE and cyclic nucleotide levels, suggesting that these changes may be related to the onset of surfactant synthesis. On day 21 of gestation, the cAMP and cGMP ratio rises sharply; at the same time, the total phospholipid level is increased by 50%. At this stage, lamellar bodies are actively differentiating within type II pneumocytes and massively released into the fetal airways. The relationships between the variations of the studied biochemical parameters and the maturation processes of lung suggest that dopamine and NE could be involved in surfactant synthesis and release via their second messenger, the cyclic nucleotides. Further investigations are needed to elucidate the mechanisms regulating these changes.

Pulmonary di-and-triacylglycerols during the perinatal development of the rat

Diacylglycerol (DG) and triacylglycerol (TG) levels in rat lung tissue were determined from day 17 of gestation to day 10 post partum and studied in parallel with ultrastructural differentiation. The DG level, although rather low at all measured stages, rose significantly between days 17 and 19 and at birth. TG level increased steadily during the whole studied period and especially between days 17 and 19 and at birth. In DG as well as in TG, saturated fatty acids were predominant. The rising of TG levels paralleled the appearance and accumulation of lipid vacuoles in mesodermal cells lying in contact with type II cells. The possible role of these cells is discussed.

[Phospholipid and fatty acid composition of lamellar bodies isolated from chicken lungs at different stages of development]

In order to elucidate whether the lamellar body content represents functional surfactant as soon as these bodies appear in lung epithelium during fetal development, lamellar bodies were isolated from lungs of Chicken at various developmental stages. Their content was analyzed and compared to extra-cellular functionnal surfactant. The results show that this content undergoes gradual changes in the phospholipid/protein ratio, as well as in the relative phosphatidylcholine amount. Thus, in the Chicken, nascent lamellar bodies do not represent the final form of extracellular surfactant.

The endocrine control of embryonic lung maturation in the chicken. I. Morphological and biochemical differentiation of lungs after "in ovo" decapitation

The effects of "in ovo" hypophysectomy on lung maturation of the chick embryo were investigated. Both biochemical and morphological aspects of differentiation were markedly delayed in experimental embryos: the phospholipid content of lungs was lower than in controls at all stages, whereas the water content remained very high. The type II pneumocytes, which normally appear within the epithelium on day 16 of incubation, started to differentiate only between days 18 and 20 of incubation in the decapitated embryos. The differentiation of type I pneumocytes leading to the formation of air capillaries was also slowed down: they did not appear until the end of incubation in decapitated embryos, whereas they normally start to appear on day 19. The presence of an intact hypophysis is thus essential for normal lung maturation in the chicken.

The endocrine control of embryonic lung maturation in the chicken. II. Role of the hypophysis

In order to discover whether the embryonic chick hypophysis acts upon lung maturation directly or via its corticotrophic activity, immature lung primordia were grafted into young hosts, either alone or associated with functional adrenals or pituitaries. When lung primordia were grafted alone, type II pneumocytes did not differentiate. Their differentiation was restored when lung primordia were grafted in association with either adrenals or pituitaries. This last result, which was also obtained in vitro, shows that the hypophysis is able, by itself, to promote the maturation of respiratory epithelium.

Lipid and phospholipid content and fatty acid composition of the chick lung during embryonic development

The evolution of total phospholipid, phosphatidylcholine and phosphatidylethanolamine content of chick lung during embryonic development is in good agreement with morphological data. Saturated fatty acids are predominant. A sex-linked difference is observed in the evolution of phosphatidylcholine.