Adaptation of the disector method to rare small organelles in TEM sections exemplified by counting synaptic bodies in the rat pineal gland

The disector is the only objective method for quantifying particles of variable size in a given volume. With this method, cell organelles are identified on adjacent sections, but only those present in one section are counted. When counting extremely rare structures in transmission electron microscope sections (physical disector), the usual procedure of counting on electron micrographs is limited for economic reasons (e.g. micrographs highly outnumbering the investigated structures). Hence, to apply this unbiased stereological method, a modification of the physical disector concerning 3 aspects has been developed. (1) The prerequisite of screening large corresponding tissue areas (here ∼65000 μm²) was fulfilled by examining tissue areas along the edges of ultrathin sections. (2) The size of the counting frame was determined by measuring the lengths of the section margins (minus a guard area) by means of a Morphomat. This value was multiplied by the width of the investigated tissue zone, corresponding to the diameter of the electron microscope viewing screen. (3) Disector counting was carried out simultaneously on both sections (bidirectional disector) to improve efficiency. In the present study tiny synaptic bodies (SBs) were quantitated by disector in a rat pineal gland, yielding ∼30 SBs/1000 μm³. By contrast, single section profile counts of SBs amounted to 90 SBs/20000 μm². Since the presently described adaptation of the disector is time-consuming, it is proposed to determine a proportion factor allowing to estimate number of structures per volume based on single section profile counts. This would decrease the evaluation time by more than 50%.     

The'Lightspeed'preparation technique evaluated by Swiss clinicians after attending continuing education courses

This survey evaluated acceptance of the Lightspeed canal preparation (LS) technique by Swiss practitioners. The technique was introduced to Switzerland inJune 1994and 10 other continuing education (CE) courses were held at the Zurich Dental School by July 1995. Acceptance was assessed by posting questionnaires to the CE course attendees. Of the 305 questionnaires posted, 177 (58%) were returned. Of the CE participants 80% had used the technique with 60% finding the method easier and 43% finding it quicker than their usual preparation techniques. Of the respondents 58% used the technique on all tooth types and 76% of the LS users had fractured an instrument at least once. Amongst others, fractures were caused by too much pressure (25%), incorrect insertion angles (17%) and by a complicated root morphology (15%). Fractures occurred high up on the instrument shaft (74%) and near the tip (7%). Working lengths were claimed by 62% to be easier to maintain by LS than their usual preparation techniques. Among the respondents 52% obturated LS prepared canals more easily and quickly compared with their usual preparation techniques. Only 10% of LS users would not recommend the technique, but those who would suggested that proper tuition was necessary to minimize the risk of instrument fracture. The LS technique was positively assessed by clinicians who attended the CE courses in Switzerland where endodontics is not accepted as a speciality     

Identification of the Philadelphia (Ph-1) Chromosome

The presence of a marker G, which later converted into the Ph-1 chromosome, in a female patient with chronic myelogenous leukemia, permittedidentification of the G chromosome from which the Ph-1 originated as a member of the early replicating, G-22 pair.

Submitted on May 13, 1969 Accepted on July 31, 1969     

Modifications of the urethral rest and stress profiles after different types of surgery for urinary stress incontinence

Summary. Full urodynamic assessment, including urethral profiles at rest and under stress, using microtransducers, was made before and at least 6 months after surgery for urinary stress incontinence in 86 patients. Cure was assessed objectively. Procedures compared were Burch colposus-pension, Pereyra urethrovesical suspension and anterior colporrhaphy. The Burch colposuspension increased the pressure transmission ratio more efficiently than the vaginal operations and the cure rate was 91%. Only 50% of Pereyra operations were successful and success was related to an increase in the functional urethral length and in the pressure transmission ratio. The success rate for anterior colporrhaphy was 57% and was associated with a significant decrease in the maximal urethral closure pressure and the continence area. The prognostic value of the urethral profiles at rest and under stress and the therapeutic implications are discussed.     

Studies on Reproduction in Rats with Meclofenamate Sodium, a Nonsteroidal Anti-inflammatory Agent

Studies on Reproduction in Rats with Meclofenamate Sodium, aNonsteroidal Anti-inflammatory Agent. PETRERE, J. A., HUMPHREY,R. R., ANDERSON, J. A., FITZGERALD, J. E., AND DE LA IGLESIA,F. A. (1985). Fundam. Appl. Toxicol. 5, 665–671. Reproductionand teratology studies were performed in rats given meclofenamatesodium, a nonsteroidal anti-inflammatory agent. Dosages of 0,3, 6, and 9 mg/kg were administered orally as dietary admixturesin the Fertility and Perinatal-Postnatal studies. In the Teratologystudy, dosages of 10, 12, 15, and 20 mg/kg were administeredby intragastric intubation. In the Male-Fertility study no adverseeffects on fertility or litter and offspring parameters wereobserved in two generations. In the Female-Fertility and Perinatal-Postnatalstudies, maternal toxicity (death associated with intestinalulceration and adhesions) was particularly evident during lactation.Prolonged gestation periods, decreased weanling weights, andincreased weanling mortality were evident at dosages of 6 and9 mg/kg. Increased postimplantation loss occurred at 6 and 9mg/kg in the Term Sacrifice subgroup of the Female-Fertilitystudy. Fertility rates were unaffected and all other litterand offspring parameters of the F₁ and F₂ generations appearednormal. In the Teratology study no adverse effects on embryonicor fetal development were evident at maternally toxic dosagesup to 20 mg/kg. © 1985 Society of Texicology.     

Synthesis of thymosin α1 by fragment condensation using tert.-butyl side chain protection

A novel synthesis of thymosin α₁ by classical methods using seven tert. -butyl side chain protected fragments is described. Optimum conditions were found for the final DCC/HOBt coupling of the two key intermediates; decapeptide and octadecapeptide. Thymosin α₁ was purified by two stages of preparative HPLC (partial purification with C₈ and final purification with C₁₈ reverse phase silica gel) to give a 30% overall yield for the final four stages of synthesis (including catalytic hydrogenation of octadecapeptide, coupling, deprotection and purification). The product was shown to be homogeneous by thin-layer and paper high voltage electrophoresis, isoelectric focusing analysis, thin-layer chromatography and high performance liquid chromatography. Amino acid analysis, optical rotation, ¹ H-n.m.r. spectroscopy, FAB mass spectroscopy and peptide mapping after tryptic digestion confirmed the structure of thymosin α₁. Three minor stereoisomer contaminants were isolated by HPLC and characterized as [D-Lys¹⁴]-thymosin α₁, [D-Lys¹⁷]-thymosin α₁ and [D-Ala³]-thymosin α₁ resulting from racemization at Lys¹⁴, Lys¹⁷ and Ala³ during the coupling of the fragments. A final contaminant, isolated by HPLC, was characterized as N^α-isobutyloxycarbonyl-thymosin α₁ (15–28), which results from “wrong way opening” of an activated mixed anhydride.     

Teratology Study in Rats with Amsacrine, an Antineoplastic Agent

Teratology Study in Rats with Amsacrine, an Antineoplastic Agent.ANDERSON, J. A., PETRERE, J. A., SAKOWSKI, R., FITZGERALD, J.E., AND DE LA IGLESIA, F. A. (1986). Fundam. Appl. Toxicol.7, 214–220. Amsacrine, an acndinylamino derivative usedin the treatment of refractory leukemias, was evaluated forits teratogenic potential in pregnant rats. The compound wasgiven by intrapentoneal (ip) administration on Days 6 to 9 ofgestation to groups of 20 female CD rats at levels of 0.5, 1.0,and 2.0 mg/kg. Appropriate vehicle and untreated controls wereincluded. Dams given 2.0 mg/kg lost weight during and afterthe treatment period. Food consumption was comparable to controlsat all dose levels except for the high dose group in the post-treatmentperiod. Decreased litter size, increased postimplantation loss,and reduced fetal weights occurred with doses of 2.0 mg/kg.Significantly reduced fetal body weight and increased incidenceof stunting were the only adverse findings at 0.5 and 1.0 mg/kg,respectively. Two fetuses at 2.0 mg/kg, one at 1.0 mg/kg, oneat 0.5 mg/kg, and two vehicle control fetuses had gross abnormalities.Fetotoxicity, manifested by inhibition of osteogenesis and minorskeletal abnormalities, occurred with doses of 0.5 mg/kg ormore. The results indicate that amsacrine was embryolethal torats at doses of 2.0 mg/kg and embryotoxic at lower dose levels.Teratogenicity was not evident at doses which did not affectfetal survival.