R. de Graaf

Hereditary neuropathy with liability to pressure palsies: A clinical, electroneurophysiological and morphological study

Clinical, electroneurographic and myographic studies were performed on 99 patients of 13 families having hereditary neuropathy with liability to pressure palsies (HNPP) and on 116 relatives. Diagnosis was confirmed in all families by a nerve biopsy of the index case. Large focal myelin thickenings (tomacula) were found in nerve biopsies of affected persons, whether or not pressure palsies had occurred. By using three electroneurographical parameters it was possible to discriminate between asymptomatic patients and unaffected relatives. Complaints sometimes mentioned in literature as being associated with HNPP such as low back pain, brachialgia and short lasting paraesthesia are not related to HNPP. The hereditary transmission is autosomal dominant with total penetration but variable expression.

The prebiotic synthesis of carbohydrates: A reassessment

SummaryQuestions concerning the significance of previous work on the formose reaction have led us to reexamine the question of the prebiotic synthesis of sugars. The results of new experiments lead to the following conclusions: The formose reaction is a geochemically plausible reaction which depends on neither basic conditions nor on the presence of trace amounts of carbohydrate impurities. However, this process is not a plausible source of ribose nor of any other individual sugar. In contrast to the nonspecific formation of complex mixtures of sugars via the formose reaction, the reduced sugar pentaerythritol is formed with great selectivity by the ultraviolet irradiation of 0.1 M formaldehyde. This compound may have played an important role in chemical evolution.

The maturation of the central auditory conduction in preterm infants until three months post term. II: The auditory brainstem responses (ABRs)

Auditory cortical evoked responses (ACRs) were recorded in 65 preterm infants, at least on 3 occasions in 48 of them. The infants were divided into 5 groups according to their gestational age (GA). The recording sessions were performed at 8 conceptional age (CA) levels, defined as the gestational age added to the chronological age. The last recordings were obtained at 50-52 weeks CA. The ACRs were analyzed for the primary complex containing middle latency components (MLR) and the secondary complex, containing the slow late components. The ACR records first appear at about 25 weeks CA, initiating the premature stage followed by a transitional stage around term date and the gradual development into the mature stage, achieved at 50-52 weeks CA. The detectability rate of the various components generally increased with increasing conceptional age, for some of the components, especially N2p and N2, this rate achieved a value of about 80%. The degree of prematurity did not influence appreciably the development of the ACR. The waveforms, and to a lesser extent the latency and amplitude values, are strongly age dependent. Remarkable topographic differences between the ACR parameter latency and more importantly amplitude values are found between the derivations from the vertex and the central temporal areas, supporting the theory of different generation sites for the ACR components. The premature and mature ACR appeared relatively insensitive to changes in the states of vigilance. The ACR in premature infants are useful in developmental studies with respect to the central audition in premature infants and might contribute in the clinical assessment on the quality of the premature central auditory system.

Chemical Reduction of Phosphate on the Primitive Earth

If phosphorus played a role in the origin of life, some means of concentrating micromolar levels of phosphate (derived from the calcium phosphate mineral apatite), must first have been available. Here we show that simulated (mini)lightning discharges in model prebiotic atmospheres, including only minimally reducing ones, reduce orthophosphates, including apatite, to produce substantial yields of phosphite. Electrical discharges associated with volcanic eruptions could have provided a particularly suitable environment for this process. Production of relatively soluble and reactive phosphite salts could have supplied a pathway by which the first phosphorus atoms were incorporated into (pre)biological systems.

On-line detection of root-induced volatiles in Brassica nigra plants infested with Delia radicum L. root fly larvae

Plants emit various volatile organic compounds (VOCs) upon herbivore attack. These VOC emissions often show temporal dynamics which may influence the behavior of natural enemies using these volatiles as cues. This study analyzes on-line VOC emissions by roots of Brassica nigra plants under attack by cabbage root fly larvae, Delia radicum. Root emitted VOCs were detected using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) and Gas Chromatography-Mass Spectrometry (GC-MS). These analyses showed that several sulfur containing compounds, such as methanethiol, dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and glucosinolate breakdown products, such as thiocyanates (TC) and isothiocyanates (ITC), were emitted by the roots in response to infestation. The emissions were subdivided into early responses, emerging within 1-6 h after infestation, and late responses, evolving only after 6-12 h. The marker for rapid responses was detected at m/z 60. The ion detected at m/z 60 was identified as thiocyanic acid, which is also a prominent fragment in some TC or ITC spectra. The emission of m/z 60 stopped when the larvae had pupated, which makes it an excellent indicator for actively feeding larvae. Methanethiol, DMS and DMDS levels increased much later in infested roots, indicating that activation of enzymes or genes involved in the production of these compounds may be required. Earlier studies have shown that both early and late responses can play a role in tritrophic interactions associated with Brassica species. Moreover, the identification of these root induced responses will help to design non-invasive analytical procedures to assess root infestations.

Reduction and Activation of Phosphate on the Primitive Earth

Electrical discharges in water-saturated N2 containing 1–10% CH4 were shown earlier toreduce phosphate to phosphite. This mechanism was suggestedas a possible source of water-soluble phosphorus-containing compounds in volcanic environments on the prebiotic Earth.We have now extended our investigations to gas mixtures inwhich CO2 and N2 are the main components, and studied the effect of introducing smallamounts of H2 and CO.We show that surprisingly high conversions to phosphite occurin reducing mixtures and thatseveral percent reduction of apatite occurs even in thepresence of as little as 1% each of H2 and CO. We were also able to confirm a previous report ofpolyphosphate production as a result of heating the mineral apatite in the presence of other minerals.

Reactive Phosphonic Acids as Prebiotic Carriers of Phosphorus

Abstract. Phosphonic acids are the only phosphorus-containing organic compounds detected in the Murchison meteorite. We earlier described the synthesis of methyl-, hydroxymethyl-, and 1-hydroxyethyl phosphonic acids using sodium phosphite as a source of phosphite radicals. We now show that ultraviolet irradiation of dilute aqueous solutions of acetylene in the presence of sodium phosphite leads to the synthesis of vinyl phosphonic acid. At neutral to basic pH, vinyl phosphonic acid reacts under photochemical conditions to produce phosphonoacetaldehyde and 2-hydroxyethyl phosphonic acid as the major products, as well as smaller yields of 1-hydroxyethyl phosphonic acid, phosphonoacetic acid, and ethyl phosphonic acid. Of these products, phosphonoacetaldehyde is particularly interesting as a potential precursor of prebiotic carbohydrate derivatives.

Use of the enzyme-linked immunosorbent assay for the early diagnosis ofMycoplasma pneumoniae infection

IgM and IgG antibodies toMycoplasma pneumoniae were measured in 147 sera from four groups of patients by means of an indirect enzyme-linked immunosorbent assay (ELISA) and the results compared with those obtained by other methods. A good correlation was demonstrated between the complement fixation test and ELISA-IgM and to a lesser extent ELISA-IgG; for the metabolic inhibition test the reverse was the case. The indirect haemagglutination test appeared to detect mainly IgM antibodies. Low levels of IgM antibodies were dectected by ELISA in 60 sera of children not suffering from pneumonia. However, if only high titres (> 800) were regarded as indicative ofMycoplasma pneumoniae infection, a presumptive diagnosis could have been made in 42 of 73 single acute phase sera from patients. Comparable results were obtained with IHA. The diagnostic level of IgM antibodies was reached during the second week of the disease. It is concluded that examination of a single serum sample by either ELISA-IgM or IHA may assist in early diagnosis ofMycoplasma pneumoniae infection.

The maturation of the central auditory conduction in preteram infants until three months post term. III. The middle latency auditory evoked response (MLR)

Middle latency auditory evoked responses (MLRs) were recorded in 64 premature infants; serially in 54 of them. The last recording sessions occurred at 50-52 weeks conceptional age (CA), defined as the gestational age (GA) added to the chronological age. The MLRs were analyzed for the components PO, Na and Pa, and the interpeak latency difference (IPLD) Na-PO. The detectability rate of PO and Na reached 80-90% at about 30 weeks CA. Pa reached the highest rate of about 60% at 52 weeks CA. The degree of prematurity did not result in clear differences with respect to the parameter values. Also, the side of stimulation did not influence the MLR parameter values. The latency values of the MLR components are strongly age dependent. Topographic differences were found between the sides ipsi- and contralateral to stimulation. They are, however, different for PO, Na and Pa. The influence of the state of vigilance on the parameter values could generally only be established at CA levels of about 32 and 52 weeks CA. The amplitude values at 52 weeks CA are especially sensitive for sleep or awake state. The particular pattern of age dependency of the different components and their topographic differences are consistent with a differential generation of bilateral nature. The early appearance of the response supports the generation of an early functioning subcortical structure in the auditory pathway.

Thermal synthesis of nucleoside H-phosphonates under mild conditions

Nucleosides react rapidly with ammonium phosphite ((NH4)2HPO3) at 60 °C to produce good yields of nucleoside-5’-phosphite monoesters within 24 h. Under the same conditions, ammonium phosphate is unreactive, producing low yields of nucleotide only after extended reactions. These results confirm earlier suggestions that nucleoside H-phosphonates and their possible condensation products may have been produced on the primitive earth more easily than nucleotides.