Revolutionizing Dental Care: A Comprehensive Review of Artificial Intelligence Applications Among Various Dental Specialties

Since the beginning of recorded history, the human brain has been one of the most intriguing structures for scientists and engineers. Over the centuries, newer technologies have been developed based on principles that seek to mimic their functioning, but the creation of a machine that can think and behave like a human remains an unattainable fantasy. This idea is now known as "artificial intelligence". Dentistry has begun to experience the effects of artificial intelligence (AI). These include image enhancement for radiology, which improves the visibility of dental structures and facilitates disease diagnosis. AI has also been utilized for the identification of periapical lesions and root anatomy in endodontics, as well as for the diagnosis of periodontitis. This review is intended to provide a comprehensive overview of the use of AI in modern dentistry's numerous specialties. The relevant publications published between March 1987 and July 2023 were identified through an exhaustive search. Studies published in English were selected and included data regarding AI applications among various dental specialties. Dental practice involves more than just disease diagnosis, including correlation with clinical findings and administering treatment to patients. AI cannot replace dentists. However, a comprehensive understanding of AI concepts and techniques will be advantageous in the future. AI models for dental applications are currently being developed.

Pseudodirect to Direct Compositional Crossover in Wurtzite GaP/InxGa1-xP Core-Shell Nanowires

Thanks to their uniqueness, nanowires allow the realization of novel semiconductor crystal structures with yet unexplored properties, which can be key to overcome current technological limits. Here we develop the growth of wurtzite GaP/In_xGa_1-xP core-shell nanowires with tunable indium concentration and optical emission in the visible region from 590 nm (2.1 eV) to 760 nm (1.6 eV). We demonstrate a pseudodirect (Γ_8c-Γ_9v) to direct (Γ_7c-Γ_9v) transition crossover through experimental and theoretical approach. Time resolved and temperature dependent photoluminescence measurements were used, which led to the observation of a steep change in carrier lifetime and temperature dependence by respectively one and 3 orders of magnitude in the range 0.28 ± 0.04 ≤ x ≤ 0.41 ± 0.04. Our work reveals the electronic properties of wurtzite In_xGa_1-xP.

Transverse circular-polarized Bessel beam generation by inward cylindrical aperture distribution

In this paper the focusing capability of a radiating aperture implementing an inward cylindrical traveling wave tangential electric field distribution directed along a fixed polarization unit vector is investigated. In particular, it is shown that such an aperture distribution generates a non-diffractive Bessel beam whose transverse component (with respect to the normal of the radiating aperture) of the electric field takes the form of a zero-th order Bessel function. As a practical implementation of the theoretical analysis, a circular-polarized Bessel beam launcher, made by a radial parallel plate waveguide loaded with several slot pairs, arranged on a spiral pattern, is designed and optimized. The proposed launcher performance agrees with the theoretical model and exhibits an excellent polarization purity.

Generation of non-diffractive Bessel beams by inward cylindrical traveling wave aperture distributions

The focusing capabilities of an inward cylindrical traveling wave aperture distribution and the non-diffractive behaviour of its radiated field are analyzed. The wave dynamics of the infinite aperture radiated field is clearly unveiled by means of closed form expressions, based on incomplete Hankel functions, and their ray interpretation. The non-diffractive behaviour is also confirmed for finite apertures up to a defined limited range. A radial waveguide made by metallic gratings over a ground plane and fed by a coaxial feed is used to validate numerically the analytical results. The proposed system and accurate analysis of non-diffractive Bessel beams launched by inward waves opens new opportunities for planar, low profile beam generators at microwaves, Terahertz and optics.

Effect of ropivacaine infiltration on muscle regeneration: a morphometric analysis

BACKGROUND/AIM

Local anaesthetic myotoxicity is a well described phenomenon resulting in reversible muscle damage. Considering that in previous studies microscopic images were evaluated without quantification of morphologic characteristics, the aim of the present study was evaluate muscle regeneration after local anaesthetic infiltration.

MATERIALS AND METHODS

Wistar rats underwent injection of the left tibialis anterior muscle with ropivacaine (0.75%, group HC or 0.375%, group LC), while the contralateral muscle was injected with saline (group SL). Six weeks later, the muscles were dissected, stained using acid ATPase and examined under light microscope coupled with a computer imaging system for morphometric analysis. Sections were evaluated regarding the content of different muscle fibre types (type I, IIa and IIb), fibre cross-section area and perimeter.

RESULTS

Groups were comparable regarding the ratio of different muscle fibre types. Regenerated type I fibres of both HC and LC groups had significant greater mean cross-sectional area and perimeter, compared to SL fibres. No signs of necrosis or inflammation were observed. Type IIa and IIb fibres didn't show significant differences.

CONCLUSIONS

Regenerated muscles, following local anaesthetic application, showed long-term morphological differences, which could lead to impaired function. Further studies are needed, in order to clarify the underlying cellular mechanisms and the subsequent possible functional impairment.

Sciatic nerve crush evokes a biphasic TGF-beta and decorin modulation in the rat spinal cord

BACKGROUND AND AIM

Inherent property of the motoneurons of the peripheral nervous system is their ability to recover, at least in part, upon injury. To this end different factors are expressed and are thought to play important role in the regeneration processes. These factors are diverse, and range from transcription factors and chemokines, to molecules of the extracellular matrix. Transforming growth factor beta (TGF-beta) is a protein with diverse actions controlling cell growth and proliferation. In the extracellular matrix it is found bound to decorin a proteoglycan involved in cell adhesion and cell signaling. In the present study we investigate the expression of TGF-beta and decorin at different time points, in the regenerating sciatic nerve of a seven day old rat, having suffered nerve crush injury, over a period of one month.

MATERIALS AND METHODS

To achieve this, we evoked injury to male Wistar rats by exposing and applying pressure to the sciatic nerve using watchmaker's forceps. After that at 12 h, 24 h, 48 h, 72 h, one week, and one month intervals we investigated the gene expression of decorin using RT-PCR, and followed the expression of TGF-beta molecule by immunohistochemistry in frozen sections of the L4-L5 region of the rat spinal cord.

RESULTS

We report that both decorin mRNA and TGF- protein exhibit a concerted, biphasic expression after 12 hours and one month having the animal suffered the nerve crush.

DISCUSSION

Our data reveal a biphasic modulation of TGF-beta protein and decorin mRNA expression at lumbar segment of the spinal cord of animals having suffered unilateral sciatic nerve crush. We postulate that their concerted expression both at an early and a late phase after the nerve injury is of importance and can be part of a repair or neuroprotective mechanism as yet unclarified.

The role of ascorbic acid and exercise in chronic ischemia of skeletal muscle in rats

This study was designed to investigate the effects of peripheral arterial insufficiency, exercise, and vitamin C administration on muscle performance, cross-sectional area, and ultrastructural morphology in extensor digitorum longus (EDL) and soleus (Sol) muscles in rats. Adult Wistar rats were assigned to ischemia alone (isch), ischemia-exercised (exe), ischemia-vitamin C (vit C), and ischemia-exercise-vitamin C (vit C + exe) groups. Ischemia was achieved via unilateral ligation of the right common iliac artery. Contralateral muscles within the same animal served as controls. Exercise protocol consisted of 50-min intermittent level running performed every other day for 5 days. Vitamin C (100 mg/kg body wt) was administered intraperitoneally on a daily basis throughout the 14 days of the experiment. With regard to the EDL muscle, ischemia alone reduced muscle strength, which was not recovered after vitamin C administration. Exercise alone following ischemia induced the most severe structural damage and cross-sectional area decrease in the muscle, yet the reduction in tetanic tension was not significant. Exercise in conjunction with vitamin C administration preserved ischemia-induced EDL muscle tetanic tension. In the Sol muscle, a significant reduction in single twitch tension after vitamin C administration was found, whereas the tetanic force of the ischemic Sol was not significantly decreased compared with the contralateral muscles in any group. Ischemic Sol muscle cross-sectional area was reduced in all but the exe groups. In Sol, muscle strength was reduced in the vit C group, and mean cross-sectional area of ischemic Sol muscles was reduced in all groups except the exe group. These results illustrate that mild exercise, combined with a low dose of vitamin C supplementation, may have beneficial effects on ischemic EDL muscle with a smaller effect on the Sol muscle.

Effect of neonatal spinal transection and dorsal rhizotomy on hindlimb muscles

The purpose of this study was to elucidate the effect of deafferentation on spinal motoneurons. We studied the effects of spinal cord transection and/or dorsal rhizotomy upon the contractile properties of EDL and soleus muscle, as well as on the number of motoneurons corresponding to these muscles. Neonatal Wistar rats were randomly divided into four groups in which spinal midthoracic section (T8-T10), unilateral dorsal lumbar rhizotomy (L3-S2) or both procedures were performed on the second postnatal day (PND2). Another group served as unoperated control. At 2 months of age, the animals were evaluated for the contractile properties of a fast (EDL) and a slow (soleus) muscle. Isometric tension recordings were elicited by way of sciatic nerve branches stimulation. In addition, the incremental method was applied for the determination of the number of motor units supplying the two muscles, which was also verified by using the horseradish peroxidase (HRP) method of reverse labeling of motoneurons. Muscle alterations were confirmed by the usual biochemical staining. Our results, in agreement with the data from other researchers, show that significant muscle atrophy takes place after all experimental procedures. Additionally, spinal cord section alters the development of the dynamic properties of soleus muscle, which attains a fast profile. Following transection, the number of motor units remained unaltered, while rhizotomy affected only the soleus by reducing its motor units. The combined procedure affected both muscles, indicating that adequate synaptic input is essential for motoneuron survival.

Magnesium administration provokes motor unit survival, after sciatic nerve injury in neonatal rats

BACKGROUND

We examined the time course of the functional alterations in two types of muscles following sciatic nerve crush in neonatal rats and the neuroprotective effect of Mg2+.

METHODS

The nerve crush was performed on the 2nd postnatal day. MgSO4*7H2O was administered daily for two weeks. Animals were examined for the contractile properties and for the number of motor units of extensor digitorum longus and soleus muscles at three postnatal stages and adulthood. Four experimental groups were included in this study: i) controls, ii) axotomized rats, iii) magnesium treated controls and iv) axotomized and Mg2+-treated rats.

RESULTS

Axotomy resulted in 20% MU survival in EDL and 50% in soleus. In contrast, magnesium treatment resulted in a significant motor unit survival (40% survival in EDL and 80% in soleus). The neuroprotective effects of Mg2+ were evident immediately after the Mg2+-treatment. Immature EDL and soleus muscles were slow and fatigueable. Soleus gradually became fatigue resistant, whereas, after axotomy, soleus remained fatigueable up to adulthood. EDL gradually became fastcontracting. Tetanic contraction in axotomized EDL was just 3,3% of the control side, compared to 15,2% in Mg2+-treated adult rats. The same parameter for axotomized soleus was 12% compared to 97% in Mg2+-treated adult rats.

CONCLUSIONS

These results demonstrate that motoneuron death occurs mostly within two weeks of axotomy. Magnesium administration rescues motoneurons and increases the number of motor units surviving into adulthood. Fast and slow muscles respond differently to axotomy and to subsequent Mg2+ treatment in vivo.

[The Rapunzel syndrome: rare manifestation of a trichobezoar of the upper gastrointestinal tract]

The Rapunzel syndrome is a rare manifestation of a gastric trichobezoar with a "tail" extending throughout the small intestine and sometimes even to the colon. We report on the surgical removal of such a bezoar in a 4-year-old patient by gastrotomy--the third published case in the German literature. The syndrome is mainly seen in young girls with trichophagia psychodynamically associated with early childhood deprivation and a high comorbidity of serious pediatric psychiatric disorders. The symptoms are nonspecific and may mimic those of other pathologic gastrointestinal conditions. Clinical characteristics are a movable mass in the epigastrium and alopecia. The therapy of choice is surgery of the trichobezoar together with the whole intestinal "tail," as in most cases endoscopic removal fails due to the large extension. Early diagnosis and treatment of the Rapunzel syndrome is of eminent importance in order to avoid later fatal complications such as gastric perforation and intestinal necroses. Intensive psychiatric follow-up is mandatory for preventing relapses.

Nature and nurture in vitamin B12 deficiency

We report on a child in whom severe nutritional vitamin B12 deficiency was exacerbated by a genetic impairment of the folate cycle, causing reduced CSF concentrations of the methyl group donor 5-methyltetrahydrofolate. Some patients with vitamin B12 deficiency may benefit from high dose folic acid supplementation, even if plasma concentrations are high.

Effect of acute limb ischaemia on neuromuscular function in rats

OBJECTIVE

To locate the exact site of the primary lesion in the neuromuscular system in acutely ischaemic extremities.

DESIGN

Experimental study.

SETTING

University hospital, Greece.

ANIMALS

22 adult rats.

INTERVENTIONS

Isometric tensions of extensor digitorum longus muscles were recorded before ischaemia and every 5 minutes after the arterial occlusions by indirect stimulation. When no contractile activity was elicited, the muscle was stimulated directly and recordings made every 5 minutes. The sciatic nerve function was checked by recordings of nerve conduction velocity. Specimens from the muscles were examined under electron microscopy.

MAIN OUTCOME MEASURES

Muscle contractile properties, conduction velocity, and electron microscopic appearance.

RESULTS

After a period of about 50 minutes neuromuscular function under indirect stimulation in the ischaemic limbs was lost, whilst under direct stimulation the extensor digitorum longus muscles and the sciatic nerves still functioned. Electron microscopic study showed distinct alterations at the neuromuscular junctions.

CONCLUSIONS

The response of the neuromuscular system to acute ischaemia indicated that the neuromuscular junction is probably the site most susceptible to acute ischaemia.

A decrease in soleus muscle force generation in rats after downhill running

The purpose of the present study was to investigate the immediate and 48-hr post-exercise effects of eccentric contraction-biased exercise on the contractile properties of the soleus muscle in situ. Adult male Wistar rats were categorised into sedentary control rats (n = 10), rats studied immediately (n = 10), and rats studied 48 hours after the exercise (n = 10). The exercise protocol consisted of a 90-min intermittent downhill running (-16 degrees, 16 m/min) on a motor-driven treadmill. The contractile properties of the soleus muscle were recorded following i.p. chloral hydrate anaesthesia. Isometric twitch force (Pt), time-to-peak tension (TPT), half-relaxation time (1/2 RT), and tetanic force at stimulation frequencies of 40, 80, and 100 Hz were recorded. A low-frequency muscle fatigue protocol (stimulation at 4 Hz for 5 min) was applied to test for fatigability. The main findings indicated that Pt generation dropped both immediately and 48 hr after the exercise, while tetanic force was partially restored after 48 hr. Exercise-induced E-C coupling failure and contractile machinery disorganisation due to muscle injury are put forward as the main force reduction causes.

Reducing body myopathy with cytoplasmic bodies and rigid spine syndrome: a mixed congenital myopathy

At the age of five years a male child started to develop a progressive rigid spine, torsion scoliosis, and flexion contractures of his elbows, knees, hips, and ankles owing to severe proximal and distal muscle weakness. He had three muscle biopsies from three different muscles at ages 7, 11, and 14 years, respectively. Myopathologically, these muscle tissues contained numerous inclusions which, at the ultrastructural level, turned out to be reducing bodies and cytoplasmic bodies, often in close spatial proximity. Similar histological inclusions, although not further identified by histochemistry and electron microscopy, were seen in his maternal grandmother's biopsied muscle tissue who had developed weakness of the legs and hands after the age of 50 years. The patient's parents were healthy, but the mother's quadriceps muscle showed an increased spectrum of muscle fibre diameters. Our patient, thus, had a neuromuscular disorder, perhaps familial, presenting as a mixed congenital myopathy, i.e., reducing body myopathy with cytoplasmic bodies, of which the morphological lesions could be consistently documented over several years in his different limb muscles. While other mixed congenital myopathies had shown cores and rods, both related to sarcomeres and thus possibly morphogenetically related, cytoplasmic bodies thought to be related to Z-bands and reducing bodies dissimilar to any muscle fibre constituent do not share any common denominator. Therefore, we suggest that this neuromuscular disorder may be a unique mixed congenital myopathy, either sporadic or genetic. In the latter case, the transmission pattern suggested X-linked recessive inheritance, but an autosomal-dominant transmission with variable penetrance could not be ruled out.

Histochemical and ultrastructural characteristics of leg muscle fibres in patients with repairative abdominal aortic aneurysm (AAA)

Tibialis anterior (ta) muscle biopsies before and after elective abdominal aortic aneurysm (AAA) repair operation were obtained, in order to observe possible changes after the aortic declamping reperfusion. Open muscle biopsies were taken from each of eight patients (60-75 years old) which were processed for enzyme histochemistry, and for transmission electron microscopy (EM). Morphometric analysis was applied to estimate the number and the area of muscle fibres of each fibre type. Rectus abdominis muscle biopsies were served as controls. Before the operation the predominant elements found were the presence of atrophic muscle fibres, fibre size diversity, localised cellular reactions, increased extent of connective tissue, disappearance, in many cases, of the mosaic pattern, predominance of type I and oxidative fibres, and existence of fibres with core-like structures in the sarcoplasm. Type I fibres consisted of 66.95 +/- 9% of all muscle fibres, the mean cross sectional area of which was 3,372.8 +/- 1,016 microm(2) and of type II fibres was 3,786.5 +/- 6,046 microm(2). After the aortic clamping was performed mitochondrial swelling was found, as well as disorganisation of sarcomeres. After declamping of the aorta, there were also severe edema, local fibre necrosis, and adhesion of leucocytes, whereas muscle fibre areas became 3,935.18 micro 531 microm(2) for type I and 5,804 +/- 1,075 microm(2) for type II. The short ischemic period during aortic clamping and the subsequent reperfusion resulted mainly in ultrastructural changes.

The effects of exercise training on muscle atrophy in haemodialysis patients

BACKGROUND

Patients with end-stage renal disease on haemodialysis (HD) have limited work capacity. Many structural and functional alterations in skeletal muscles contribute to this disability.

METHODS

To evaluate the effects of exercise training on uraemic myopathy, seven HD patients (mean age 44.1+/-17.2 years) were studied. Open muscle biopsies were taken from their vastus lateralis muscle before and after a 6-month exercise rehabilitation programme and examined by routine light- and transmission electron-microscopy. Histochemical stainings of frozen sections were performed and morphometric analysis was also applied to estimate the proportion of each fibre type and the muscle fibre area. Spiroergometric and neurophysiological testing and peak extension forces of the lower limbs were measured before and after exercise training.

RESULTS

All patients showed impaired exercise capacity, which was associated with marked muscular atrophy (mean area 2548+/-463 microm2) and reduction in muscle strength and nerve conduction velocity. All types of fibres were atrophied, but type II were more affected. The ultrastructural study showed severe degenerative changes in skeletal muscle fibres, mitochondria, and capillaries. Exercise training had an impressive effect on muscular atrophy; in particular the proportion of type II fibres increased by 51% and mean muscle fibre area by 29%. Favourable changes were also seen on the structure and number of capillaries and mitochondria. These results were confirmed by a 48% increase in VO2 peak and a 29% in exercise time, as well as an improvement in the peak muscle strength of the lower limbs and in nerve conduction velocity.

CONCLUSIONS

Skeletal muscle atrophy in HD patients contribute to their poor exercise tolerance. The application of an exercise training rehabilitation programme improved muscle atrophy markedly, and therefore had beneficial effects in overall work performance.

Ontogenetic development of the locomotor response to levodopa in the rat

Administration of exogenous levedopa triggers locomotion in young rats prior to the onset of quadripedal movement. The same substance decreases locomotion in adult animals. The ontogenetic development of the response to levodopa was investigated in rats. Intraperitoneal injection of levodopa (150 micrograms/kg body weight) caused characteristic "crawling" or "swimming-like" locomotion patterns in 5- to 6-day-old animals. Noradrenergic mechanisms may be involved in this behavior. In 18- to 20-day-old rats, levodopa caused excessive locomotor activity, including running, jumping, and wall climbing. This effect can be attributed to the activation of postsynaptic dopaminergic receptors that are already present during the early stages of life. At 25-30 days of age, levodopa-induced motor activity was decreased in comparison with that of the 18- to 20-day-old rats, possibly due to changing patterns of D1/D2-dopamine receptor subtype interactions. In contrast to observations in younger rats, the same dose of levodopa suppressed motor activity in 60- to 75-day-old rats. The presence of functional dopamine autoreceptors at this age may account for the change.

Giant axonal neuropathy and leukodystrophy

An 11-year-old Persian boy, born to consanguineous parents, manifested a progressive gait abnormality beginning at 5 years of age. A severe cerebellar disorder developed with associated dysfunction of the peripheral nervous system, but no sign of mental impairment. The sensory and motor nerve conduction velocities were greatly reduced, especially in the lower extremities. Cerebrospinal fluid protein was normal. Computed tomography and magnetic resonance imaging revealed leukoencephalopathy, especially in the cerebellum, but also in periventricular areas. The diagnosis of giant axonal neuropathy was established by biopsy of the sural nerve. The few previous histologic examinations have documented hyperplasia of the microfibrils which accumulate in the axons as well as in neurilemma, endothelial, and perineural cells. This is the first report of involvement of supraspinal portions of the central nervous system documented by postmortem examination after in vivo imaging methods corroborated the morphologic concomitants of the clinical symptoms.

Decreased binding of HIV-1 and vasoactive intestinal peptide following plasma membrane fluidization of CD4+ cells by phenytoin

Plasma membrane fluidity of intact peripheral blood lymphocytes (PBL) of phenytoin-treated nonepileptic patients and phenytoin-treated CD4+ lymphoid cells H9 and K37 was determined by fluorescence anisotropy measurements. Anisotropy values of the membrane probe 6-(9-anthroyloxy) stearic acid were decreased in all cell types as compared with controls, indicating increased plasma membrane fluidity of phenytoin-treated cells. Specific binding of 125I-labeled vasoactive intestinal peptide (VIP) to its cellular receptor CD4 on PBL was decreased in PBL of phenytoin-treated patients as compared with untreated, healthy subjects. Adsorption of a different ligand to the CD4 receptor on PBL, the human immunodeficiency virus type 1 (HIV-1), was likewise abolished to PBL of phenytoin-treated patients and phenytoin-treated CD4+ H9 and K37 cells, as assessed by indirect immunofluorescence. Subsequent HIV-1 infection of phenytoin-treated H9 and K37 cells was reduced as measured by indirect immunofluorescence and p24 antigen production. These data indicate that CD4 receptor availability for VIP and HIV-1 was reduced in phenytoin-treated cells. Using the DNA-specific dye Hoechst 33258, we examined cell cycle phase distributions of HIV-1 adsorbing and nonadsorbing H9 cells, as separated by flow cytometry. The majority of HIV-1 adsorbing cells were found to be in the G2/M phase, while nonadsorbing cells were mainly in the G0/G1 phase, during which plasma membrane fluidity is supposed to be increased. This study indicates that plasma membrane fluidization by phenytoin may serve to disrupt CD4 receptor function and emphasizes the impact of plasma membrane properties on HIV-1 adsorption and infection.

[Bronchial asthma and homozygous alpha-1-antitrypsin deficiency (PiZZ) in 3 members of a family]

We report on a family of an 8-year-old boy who suffers from bronchial asthma. In a routine screening for Alpha-1-antitrypsin-deficiency we discovered a homozygote PiZZ-type which is asymptomatic with regard to complications of the liver or a lung-emphysema. Two other members of the family show the same coincidence of bronchial asthma and Alpha-1-antitrypsin-deficiency, while two further members of the family with a heterozygote PiMZ-type are free of symptoms of the lower airways. Possible relations are discussed.

Increased plasma membrane fluidity and decreased receptor availability of nonmuscle cells in myotonic dystrophy

Plasma membrane fluidity of intact nonmuscle cells from patients with myotonic dystrophy (MyD) was determined by fluorescence anisotropy measurements. Anisotropy values of the probe diphenylhexatriene were decreased in patient mononuclear cells (0.163 +/- 0.017, n = 13) versus controls (0.181 +/- 0.013, n = 13, P less than 0.01) and in patient platelets (0.087 +/- 0.017, n = 9) versus controls (0.137 +/- 0.015, n = 9, P less than 0.001) indicating increased plasma membrane fluidity in patient nonmuscle cells. Vasopressin plasma concentrations were increased in patients (7.4 +/- 2.1 pg/ml, n = 12) versus controls (4.5 +/- 1.4 pg/ml, n = 22, P less than 0.0005), whereas serum osmolality was normal. These data are compatible with a decreased vasopressin sensitivity in MyD patients. Specific binding of 125I-labelled vasoactive intestinal peptide (VIP) was decreased in patient mononuclear cells (2.9 +/- 0.9%/10(6) cells, n = 8) versus controls (5.2 +/- 1.6%/10(6) cells, n = 9, P less than 0.005) and receptor affinity for VIP was decreased in patient mononuclear cells (Kd = 0.26 +/- 0.05 nM, n = 8) versus controls (Kd = 0.19 +/- 0.02 nM, n = 9, P less than 0.005). In nonmuscle cells of MyD patients, increased membrane fluidity correlated with decreased receptor availability. This might explain the various endocrine defects described in MyD patients.

[Nightly home artificial respiration in juvenile Pompe's disease with pulmonary hypertension and right cardiac insufficiency]

A 17-year-old girl with type II glycogen storage disease (Pompe's) developed severe right-heart failure as a result of pulmonary hypertension due to, predominantly nocturnal, hypoventilation. At night the partial pressure of oxygen was only 30-50 mmHg, pCO2 70-100 mmHg. After persistent nightly intermittent positive pressure ventilation blood gases as well as electrocardiographic and echocardiographic findings have now--after 12 months--become normal and the patient has been completely restored to a normal life. This case demonstrates that life expectancy and quality of patients with chronic forms of Pompe's disease (and probably also with other chronic neuromuscular diseases) can be markedly improved by nightly artificial ventilation which reduces nocturnal hypoventilation and resulting pulmonary hypertension.

A membrane fluidizing factor in sera from Duchenne muscular dystrophy patients: effect on lymphocyte membranes of incubation in patient and control lipoproteins

Sera from Duchenne muscular dystrophy (DMD) patients showed a membrane fluidizing effect on DMD and control lymphocytes. To look for the cause of this membrane fluidizing effect, human lymphocytes from healthy subjects were incubated in sera and in different serum fractions from DMD patients and healthy control subjects, and membrane fluidity was determined by steady state fluorescence polarization of the probe diphenyl hexatriene. DMD sera and total DMD lipoproteins showed a similar membrane fluidizing effect (p less than 0.02) after incubation, whereas lipoprotein deficient serum did not show any effect on membrane fluidity. Control and DMD HDL showed a membrane fluidizing effect, the fluidizing effect of DMD HDL being slightly higher as compared to control HDL. Control LDL and DMD LDL showed a membrane rigidifying effect, the rigidifying effect of DMD LDL being significantly lower as compared to control LDL (p less than 0.02). These data demonstrate that the membrane fluidizing effect of DMD serum is lipoprotein associated, LDL being the most important mediator of this effect.

Reorganization of motor units in reinnervated muscles of the rat

Changes in motor unit organisation following nerve injury in adult and neonatal rats were compared. Motor units were studied in extensor digitorum longus muscles reinnervated after nerve injury in either neonatal or adult rats. The force developed by individual motor units was measured by stimulating ventral root filaments. After nerve section in adult rats the distribution of motor unit force was restored to normal but this did not occur following nerve crush in neonatal animals. Thus following nerve injury during the neonatal period the muscles were not only permanently weaker, but the distribution of motor unit sizes was also abnormal. Muscle fibres belonging to a single motor unit were identified histologically by the glycogen depletion method, and their fibre type and cross-sectional area measured. Although all the fibres of the same unit became histochemically homogeneous, they showed greater variation in size than normal units, suggesting that factors other than the influence of the axons control the size of muscle fibres.

Juvenile neuronal ceroid lipofuscinosis (JNCL): quantitative description of its clinical variability

The clinical courses of 17 JNCL patients were analyzed retrospectively with the use of a simple, disease-specific scoring system. The mean observation period was 14 years (range 8-18 years). Scores of 0 (maximal dysfunction) to 3 (normal function) were assigned to each patient's vision, intellect, language, motor function, and epilepsy for each year of observation. The lapse of medians and ranges of all patients' scores were established from age 3 to 20 years. This scoring system allowed quantitative description of an individual course in context of the wide natural variability of the disease. Patients with seizures starting before the age of 10 years tended to have intractable epilepsy, to receive multiple antiepileptic drug therapies, and to have poor courses including problems not related to epilepsy. One patient had a course clearly outside the usual variability of JNCL and is thought to represent a genetic variant.

Are there tests predictive for prolonged apnoea and SIDS? A review of epidemiological and functional studies

Sudden infant death syndrome (SIDS) remains the predominant cause of postneonatal mortality. Epidemiological studies have led to the definition of populations with an increased risk for SIDS: subsequent siblings of SIDS victims, infants with near miss for SID episodes, prematurely born infants with perinatal risk factors, and infants of drug dependent mothers. Furthermore, a variety of additional although rarely independent factors regarding both mothers and infants have been found to be associated with an increased risk for SIDS. Despite of this, the majority of infants still dying from SIDS do not belong to one or more of these risk groups and even within a group considered to be at increased risk it is impossible so far to identify individual infants at highest risk on the basis of an infant's history and clinical data. Therefore, different methods have been applied during the last several years in order to detect functional abnormalities of cardiorespiratory control during sleep with the aim of obtaining more specific and sensitive predictors of subsequent severe apnoea and SIDS. In an attempt to evaluate the predictive power of these various methods the present article reviews their results in relation to the follow up data of the infants under study. The results of the meanwhile innumerous studies were found to be at variance and often controversial. At the present time, none of these tests may be looked at as virtually improving our ability to predict the risk for prolonged apnoea and SIDS. One of the reasons for this may be the lack of standardisation of the particular methods with respect to both definition of study groups and conditions of testing infants. Since all of these tests have mainly been performed in infants of epidemiological risk groups, the definition of which is an indispensable prerequisite for the evaluation of both the indication and the results of such tests, an updated survey of the more recent epidemiological studies is given as an introduction.

[Acute apparently life threatening events in 62 infants: anamnestic and clinical data]

Among 62 infants admitted to our hospital after an acute and apparently threatening event which according to the parents required active intervention either by tactile stimulation, or shaking or mouth to mouth ventilation were 21 previously preterm babies, 12 of whom with additional perinatal risk factors, and 41 fullterm infants, 3 of them being subsequent siblings of a SIDS victim. More than 80% of the ALTEs occurred during presumed sleep while the remaining 20% were observed during wakefullness, mostly during or shortly after feeding. The majority was said to be found pale or blue, floppy and mostly unreactive. The parents or caretakers, however, were unable to give reliable information concerning the type of breathing i.e. whether the infants were apneic or not. On admission, 71% of the pre- and 63% of the fullterms showed abnormal signs and symptoms. A total of 14 infants had symptoms of respiratory tract infections, involving the lungs in only 6 cases. An other 10 infants developed moderate enteritis after admission only; 8 of them had stool cultures positive for rotavirus antigen. On the basis of the anamnestic and clinical data including the results of the diagnostic work-up in 14 (34%) of the fullterm and 3 (14%) of the preterm infants a so far unrecognized disorder was diagnosed which in many cases gave access to a specific therapy. If the cases of infections - not including those with only mild respiratory tract involvement often found in cases of SIDs or near miss SIDS - are included in this group their number increased to 27 (43,5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Transcutaneous blood gases and sleep apnea profile in healthy preterm infants during early infancy

Studying the development of transcutaneous blood gas levels (tcpO2 and tcpCO2) and the sleep apnea profile in relation to sleep states in normal preterm infants between 36 and 52 weeks postconceptual age we found a dynamic increase in tcpO2 during regular breathing (without apnea) and a steady decrease in tcpCO2 during both regular and periodic breathing. The mean tcpO2 of periodic breathing, however, persistently remained well below the corresponding level found during regular breathing. It is suggested that in normal preterm infants there is a continued maturational adjustment of autonomic respiratory control up to 3 months post term and, furthermore, that periodic breathing may persistently be associated with a relative hypoxemia.

Sural nerve biopsy studies in Leigh's subacute necrotizing encephalomyelopathy

Peripheral neuropathy marked by reduced nerve conduction velocities was found in four unrelated children, between the ages of 15 months and 9 years, whose autopsies revealed Leigh's subacute necrotizing encephalomyelopathy. Sural nerve biopsies disclosed primary demyelination and remyelination, as well as loss of myelinated and unmyelinated axons. The use of morphometric and electron microscopic studies shows that these techniques may reveal peripheral neuropathy in Leigh's disease more often than light microscopic methods alone.

[Home monitoring of apnea in children at increased risk for sudden infant death (SIDS)]

Since 1981, 96 infants considered at increased risk of SIDS underwent home monitoring for prolonged sleep apnea: 23 infants after a near miss for SIDS event, 28 siblings of a SIDS victim and 45 infants with a variety of perinatal risk factors. For a total of 65 infants the course of home monitor surveillance was completed by September 1984 with a duration ranging from 6 to 15 month: 26% (4/15) of the near miss for SIDS group, 23% (3/13) of the SIDS siblings and 13% (5/37) of the perinatal risk cases developed more than one prolonged apneic episode with additional symptoms requiring vigorous intervention by parents. Two infants of the perinatal risk group became SIDS victims: despite an apnea alarm after 15 seconds the parents were unable to resuscitate their infant in one case, the other died from SIDS about 4 month after monitoring was discontinued because of an uneventful course and normal polygraphic sleep recordings The large number of prolonged apneas requiring intervention and the two SIDS cases (3% of the total study group) indicate a considerably increased risk of prolonged life-threatening sleep apnea and SIDS in the population monitored.

Physiological properties and pattern of innervation of regenerated muscles in the rat

The regeneration of fast and slow muscles was compared following "mincing" and replacement into their own or alien muscle bed. At intervals varying from 2 to 9 weeks the tension developed by the regenerated muscles was assessed and compared to that developed by the muscles from the contralateral unoperated side. This parameter was then taken as an indication of recovery. The regenerated muscles never developed more than half of the tension of the control muscles. Muscles regenerated in the bed of extensor digitorum longus became fast-twitch muscles and muscles regenerated in the bed of soleus became slow-twitch muscles, no matter whether they originated from an extensor digitorum longus or soleus "mince". The regeneration of the muscle tissue in the place of extensor digitorum longus developed better than in the place of soleus. The pattern of innervation of the regenerated muscles was analysed using a combined cholinesterase silver stain. Many of the regenerated fibres had more than one end plate and some end plates more than one axon terminal. These results show that in adult animals muscle redevelopment can occur, but only to a limited extent. Moreover, on reinnervation of regenerated muscle fibres the axons do not assume their original pattern of innervation.

Sleep apnoea profile in preterm infants recovering from respiratory distress syndrome

Polygraphic recordings were made on 10 preterm infants recovering from respiratory distress syndrome and 12 healthy preterm control infants at 40, 52, and 64 weeks' conceptual age to study the influence of respiratory distress syndrome on the development of the sleep apnoea profile. Two significant differences were found: infants with respiratory distress syndrome not only had a lower incidence of non-obstructive apnoea and periodic breathing at 40 weeks but also a persistently higher incidence of obstructive and mixed apnoea at 52 and 64 weeks' conceptual age; the latter finding being related to non-rapid eye movement sleep only. While the lower incidence of both types of apnoea at 40 weeks suggests an advanced maturation of respiratory drive, the persistence of obstructive and mixed apnoea related to non-rapid eye movement sleep may reflect the impact of respiratory distress syndrome on airway structures.

Infant sleep apnea profile: preterm vs. term infants

By means of polygraphic sleep recording, the sleep apnea profile with respect to the number and duration of inactive, obstructive and mixed apneic episodes as well as periodic breathing has been investigated in infants born preterm at 40, 52 and 64 weeks conceptional age and compared to that of term infants. At 40 weeks preterm infants showed significantly more apnea and periodic breathing compared to term infants. The difference was essentially due to obstructive and mixed apnea in non-REM sleep. There was a sharp decrease in all apneic variables--inactive, obstructive and mixed apnea as well as of periodic breathing--at 52 weeks conceptional age in infants that were previously preterm. Both groups exhibited a rather identical sleep apnea profile at 64 weeks. Two prospectively studied infants in the preterm group later became SIDS victims. One of them might have been identified as being at risk on the basis of his apnea profile compared to the normative data now available.

Neuronal control of neonatal respiration - sleep apnea and the sudden infant death syndrome

During the last decade evidence has been accumulated that there might be a continuum from normally occurring short spells of apnea during sleep to life threatening long lasting respiratory pauses with marked bradycardia or even cardiac arrest from which, however, the infant could be resuscitated - the so-called Near Miss for Sudden Infant Death Event - and finally, to the Sudden Infant Death Syndrome (SIDS). There are still many missing links between these three phenomena and it seems likely that the connection between all three is not a straight matter in degree of immature dysfunction of cardiorespiratory control mechanisms. However, no other concept has shead so much light on SIDS and - most probably - no other concept with its consequence of continuous home monitoring has already salvaged so many babies as research into the different sleep apnea syndromes during infancy. However, for the final evaluation of the above mentioned hypothesis two issues urgently need clarification: a) How much apnea is normal at different ages and in different risk groups of infants. b) Can "near miss infants" or future victims of SIDS be identified on the basis of the amount of apnea prior to the event. In the first part of this survey brain mechanisms possibly underlying both, sleep apnea and serious apneic events will be discussed. In the second part new normative data on the amount of apnea will be presented together with 2 extraordinary cases who could be studied by means of longterm polygraphic sleep recordings prior to a definitely serious near miss event in one case and a crib death in another.

A familial progressive neurodegenerative disease with 2-oxoglutaric aciduria

A boy and a girl born to a consanguineous Tunisian couple are suffering from a slowly progressive nervous disorder. Initially they both had normal psychomotor development with acquisition of gait and speech. First symptoms in the boy were athetoid movements during the second year of life. He later lost all motor and language skills and developed muscular rigidity and intention tremor. At the age of five years, he was completely bedridden while he appeared mentally much less affected. His younger sister followed a similar course. The major specific abnormality detected was a strikingly elevated excretion of 2-oxoglutaric acid, which was identified by gas liquid chromatography, mass spectrometry, and enzymatic analysis. 2-oxoglutarate dehydrogenase activity in homogenates of cultured skin fibroblasts was reduced to about 25% of control values in both children. Although the pathogenetic mechanisms leading to brain damage remain obscure, the finding strongly suggest an autosomal recessive neurometabolic disease with predominant involvement of the extrapyramidal system.

On the role of ribosylthymine in prokaryotic tRNA function

tRNAPhe and tRNALys were isolated from an Escherichia coli K12 mutant deficient in ribosylthymine (rT) and from the wild-type strain. The sequence G-rT-psi-C which is common to loop IV of practically all tRNAs used in the elongation cycle of protein synthesis reads G-U-psi-C in the tRNAs of the mutant strain. The purified tRNAs were compared in various steps of protein biosynthesis. The poly(U)-dependent poly(Phe) synthesis performed with purified Phe-tRNAPhe and purified elongation factors showed no dependence on the presence or absence of ribosylthymine in the respective tRNAs. In contrast, the corresponding poly(A)-dependent poly(Lys) synthesis was markedly increased when Lys-tRNALys lacking rT was used. The analysis of individual functional steps of the poly(A)-dependent elongation cycle demonstrated that the absence of rT reduced the binding to the A-site and improved the translocation reaction, whereas the formation of the ternary complex EF-Tu . GTP . aa-tRNA as well as both tRNA binding to the P-site and the peptidyltransferase reaction remained unaffected. The presence of U in place of rT in tRNA increases the misincorporation of leucine in an optimized poly(U)/poly(Phe) system from about 3 in 10 000 to 3 in 1000. Our results are in agreement with the view that rT is involved in tRNA binding to the A-site in contrast to the P-site, and suggested that the presence of rT in tRNA improves the fidelity of the decoding process at the A-site of the ribosome.

Circulating haematopoietic stem cells (CFUc) in healthy and diseased pre-term infants

During fetal life, haematopoiesis is in a physiologic state of rapid expansion. The activity of the pluripotent haematopoietic stem cell compartment of the bone marrow probably is reflected by the number and proliferative potentiality of CFUc in the blood circulation. We have studied, by the methylcellulose culture technique and without addition of exogenous colony stimulating factor (CSF), blood CFUc in pre-term and full-term newborn infants, in full-term infants 10 to 17 d of age, and in adults. Two groups of pre-term infants were studied: otherwise healthy infants and sick infants, including infants small-for-date and in perinatal distress. In healthy pre-term infants and in full-term infants 147 +/- 25 (SD) and 105 +/- 41 (SD) colonies per 100 000 lymphoid cells were formed, respectively. This is clear evidence for the presence in the blood of both. CFUc and CSF producing cells. By contrast, there was no or only slight spontaneous colony formation by sick pre-term infants, by older infants, and by adult.

Sleep induced PO2-changes in preterm infants

In seven healthy preterm infants the transcutaneous PO2 was measured during different sleep states. The tcPO2 is lower during active sleep than during quiet sleep and shows a higher variability in active sleep. The incidence of apneic spells, which occur predominantly during active sleep, was not found to be correlated to tcPO2 levels.

[Atresia of the larynx, a rare cause of postnatal respiratory distress (author's transl)]

An infraglottic atresia of the larynx with normally developed vocal cords necessitated postnatally an emergency tracheotomy after intubation attempts had failed. Laryngeal atresia is a very rare malformation. As in our example, it is in most cases accompanied by a tracheo-hypopharyngeal fistula which has to be interpreted ontogenetically. The survival chances of the newborn with this malformation are generally very poor.

Role of ribothymidine in the thermal stability of transfer RNA as monitored by proton magnetic resonance

In order to elucidate the functional role of the modified uridines at position 54 of tRNA, the 270 MHz high-field proton NMR spectra of methionine tRNAs from E. coli, from a mutant thereof, and from T. thermophilus, containing ribothymidine, uridine and 2-thioribothymidine, respectively, have been measured as a function of temperature. A comparison of the NMR melting profiles of the minor nucleosides from these tRNAs shows that the melting temperature of uridine containing tRNA is 6 degrees C lower than that of the wild type tRNA whereas that of the 2-thioribothymidine tRNA is 7 degrees C higher than that of the wild type tRNA. These results, therefore, demonstrate that these modifications serve for stabilization of the tertiary structure of tRNA.

Sleep and aminophylline treatment of apnea in preterm infants

The influence of short-term aminophylline treatment on sleep behaviour was studied in six preterms infants with recurrent apnea. The incidence of apnea, respiratory pauses, and bradycardias which were closely related to the phases of active sleep, decreased during aminophylline treatment. However, the amount of active sleep remained unaffected. The mode of action of aminophylline is discussed in view of the previously proposed neurophysiological concept of apnea of prematurity.

An unusual case of phenytoin intoxication

A case of a ten years old boy is reported who developed a severe intoxication after changing the phenytoin treatment from the calcium salt to the free acid. The difference in bioavailability reduced the drug requirement to 55% of the previous dose. The child was receiving also sodium valproate and clonazepam. Serial measurements revealed a significant inverse correlation between the toxic phenytoin serum concentration and the serum level of valproic acid. The measurements of phenytoin as well as of valproic acid in this case have shown again the value of routine monitoring of anticonvulsant therapy.