Does the guidance method affect the doses of botulinum toxin in writer's cramp?

PURPOSE: Botulinum neurotoxin (BoNT) injections are the main medical treatment of writer's cramp. When the outcome is favourable, patients usually receive injections several times per year in the long-term. However, we know little about the course of BoNT doses and nothing about the impact of the guidance method on the clinical outcome or injection strategy. METHODS: We studied, in the long-term, the doses of BoNT and the target muscles in a group of patients with writer's cramp, according to the guidance method (electrical stimulation or ultrasound). Patients received at least three injection cycles guided by electrical stimulation, followed by at least three injection cycles guided by ultrasound. RESULTS: Twenty-four patients were included. More target muscles were injected after switching to ultrasound guidance, especially the flexor carpi ulnaris and the flexor carpi radialis. The mean dose by muscle was lower when ultrasound guidance was used. When using electrical stimulation guidance, the dose in the flexors of the fingers decreased in the long-term, but increased in the flexors of the wrist. The course of the BoNT doses and of the number of target muscles per cycle were not the same during the first period (electrical stimulation) and the second period (ultrasound). CONCLUSIONS: Switching to ultrasound guidance, the BoNT dose decreased, mainly in the flexors of the wrist. Based on the results of our study, we suggest a starting dose in several muscles (flexor carpi ulnaris, flexor carpi radialis, flexor digitorum profundus and flexor pollicis longus).

Indication for molecular testing by multiplex ligation-dependent probe amplification in parkinsonism.

BACKGROUND AND PURPOSE: The monogenic forms of Parkinson's disease represent <10% of familial cases and a still lower frequency of sporadic cases. However, guidelines to orient genetic testing are lacking. The aim was to establish the interest of multiplex ligation-dependent probe amplification (MLPA) as a primary screening test and to propose clinical criteria to guide genetic diagnostic tests for patients with suspected Mendelian Parkinson's disease. METHODS: In all, 567 patients with parkinsonism from 547 unrelated families were recruited and two MLPAs were performed for each. All pathogenic G2019S variants in the LRRK2 gene were confirmed by Sanger sequencing and the PRKN gene was screened for a second mutation in the cases of one heterozygous structural variant in the PRKN gene. RESULTS: The performance of MLPA was 51/567 (9%) for the entire cohort and included 27 (4.8%) LRRK2 G2019S mutations, 19 (3.4%) PRKN mutations and five (0.9%) SNCA locus duplications. The variables significantly associated with a positive test in the total cohort were North African ancestry (p < 0.0001), female sex (p = 0.004) and younger age at onset (p < 0.0008). CONCLUSIONS: Retrospective analysis allowed us to refine our indication criteria: (i) North African ancestry, (ii) an age at onset <40 years or (iii) a familial history of parkinsonism with at least one affected first-degree relative. Our study highlights the interest of MLPA testing for other parkinsonism cases with a family history, especially for patients with dementia with Lewy bodies or a multiple-system-atrophy-like phenotype.

French validation of the Quality of life in Essential Tremor Questionnaire (QUEST) and the Essential Tremor Embarrassment Assessment (ETEA).

Two scales have been developed and validated in English to evaluate the impact of tremor on daily life, namely Quality of life in Essential Tremor Questionnaire (QUEST) and Essential Tremor Embarrassment Assessment (ETEA). The psychometric properties of the French version of these two scales were assessed for 117 patients with head tremor. Both scales showed excellent acceptability, very good internal consistency (Cronbach's alpha coefficient>0.8) and reproducibility (Lin concordance coefficient>0.8), satisfactory external validity and satisfactory sensitivity to change. In conclusion, the French versions of QUEST and ETEA are comprehensive, valid and reliable instruments for assessing patients with head tremor.

Does ultrasound-guidance improve the outcome of botulinum toxin injections in cervical dystonia?

PURPOSE: Ultrasound-guided injections of botulinum neurotoxin in cervical dystonia have a number of theoretical advantages. However, their action has never been compared to that of non-guided injections. The objectives of the study were to compare the outcome of botulinum neurotoxin type A treatment in patients with idiopathic, focal cervical dystonia, according to two methods: inspection and palpation of anatomical landmarks (non-guided group) or ultrasound guidance (ultrasound-guided group). METHODS: We included consecutive patients in this single-center, prospective, real-life, non-randomized study. The outcomes were evaluated one month after the injections: Cervical Dystonia Impact Profile 58 (main outcome), Toronto Western Spasmodic Torticollis Rating Scale-2 (pain and disability subscores), Toronto Western Spasmodic Torticollis Rating Scale-PSYCH, patient-rated Clinical Global Impression - Improvement and adverse events. We used propensity score methods for statistical analysis; ten predefined confounding factors were used to build the propensity score. RESULTS: Sixty-three patients were included in the non-guided group, and 60 other patients in the ultrasound-guided group. We found no difference in main and secondary outcomes between the two study groups. CONCLUSION: This is the first direct comparison between ultrasound-guided and non-guided botulinum neurotoxin type A injections in patients with cervical dystonia. We hypothesize that ultrasound guidance made it possible to obtain the same results in the most severe (or the most demanding) patients as in the best responders. Further studies are still needed to assess the impact of botulinum neurotoxin injections into deep cervical muscles.

Anatomy-guided injections of botulinum neurotoxin in neck muscles: how accurate is needle placement?

BACKGROUND AND PURPOSE: In cervical dystonia, the accuracy of botulinum neurotoxin (BoNT) injections may influence the response to the treatment. METHODS: We used ultrasound to evaluate the accuracy of anatomy-guided injections of BoNT in the neck muscles. RESULTS: A total of 56 consecutive patients and 332 injections were evaluated. The overall accuracy was 76.6%. The lowest accuracy (67.9%) was observed for the splenius capitis muscle. CONCLUSIONS: Anatomic guidance of BoNT injections in the neck muscles is often inaccurate. Imaging guidance may improve the accuracy of BoNT injections in cervical dystonia.

Safety and effectiveness of levodopa-carbidopa intestinal gel for advanced Parkinson's disease: A large single-center study.

BACKGROUND: Treatment with levodopa-carbidopa intestinal gel (LCIG) can effectively relieve motor and non-motor symptoms in advanced Parkinson's disease (PD). However, adverse events (AEs) are frequent. OBJECTIVE: To describe AEs associated with LCIG treatment and the main reasons for treatment discontinuation. We also looked for factors that were potentially predictive of serious AEs and assessed the effectiveness of and satisfaction with LCIG. METHOD: We retrospectively analyzed data on AEs in patients treated with LCIG at a French university medical center. For patients still receiving treatment at last follow-up, effectiveness was assessed according to the Clinical Global Impression (CGI) scale and the Movement Disorders Society - Unified Parkinson's Disease Rating Scale motor score. RESULTS: Of the 63 patients treated with LCIG for a mean (range) of 19 months (8-47), 57 (90%) experienced at least one AE (340 AEs in total). Most of the AEs (in 69.8% of the patients) were related to percutaneous endoscopic gastrostomy with a jejunal tube (PEG-J) or affected the gastrointestinal tract (granuloma, leakage, or a local infection). Device-related AEs (such as PEG-J removal and device occlusion) were frequent (in 63.5% of patients). Forty-three patients (68%) required at least one additional endoscopic procedure. Dopatherapy-related AEs occurred in 30 patients (48%). Most of the AEs occurred long after treatment initiations, and only a small proportion led to discontinuation. On the CGI scale, 53 patients (84.4%) considered that their condition had improved during LCIG treatment. CONCLUSION: Despite the high frequency of AEs, patients with advanced PD gain clinical benefit from treatment with LCIG. This treatment requires a competent, multidisciplinary team on site.

The duration of intermittent access to preferred sucrose-rich food affects binge-like intake, fat accumulation, and fasting glucose in male rats.

Many people restrict their palatable food intake. In animal models, time-limiting access to palatable foods increases their intake while decreasing intake of less preferred alternatives; negative emotional withdrawal-like behavior is sometimes reported. In drug addiction models, intermittent extended access drives greater changes in use than brief access. When it comes to palatable food, the impact of briefer vs. longer access durations within intermittent access conditions remains unclear. Here, we provided male rats with chow or with weekday access to a preferred, sucrose-rich diet (PREF) (2, 4, or 8 h daily) with chow otherwise available. Despite normal energy intake, all restricted access conditions increased weight gain by 6 weeks and shifted diet acceptance within 1 week. They increased daily and 2-h intake of PREF with individual vulnerability and decreased chow intake. Rats with the briefest access had the greatest binge-like (2-h) intake, did not lose weight on weekends despite undereating chow, and were fattier by 12 weeks. Extended access rats (8 h) showed the greatest daily intake of preferred food and corresponding undereating of chow, slower weight gain when PREF was unavailable, and more variable daily energy intake from week to week. Increased fasting glucose was seen in 2-h and 8-h access rats. During acute withdrawal from PREF to chow diet, restricted access rats showed increased locomotor activity. Thus, intermittent access broadly promoted weight gain, fasting hyperglycemia and psychomotor arousal during early withdrawal. More restricted access promoted greater binge-like intake and fat accumulation, whereas longer access promoted evidence of greater food reward tolerance.

[Continuous subcutaneous infusion of apomorphine in Parkinson's disease: retrospective analysis of a series of 81 patients]. / Le traitement par apomorphine en perfusion continue sous-cutanée dans la maladie de Parkinson : analyse rétrospective d'une série de 81 patients.

BACKGROUND: Continuous subcutaneous infusion of apomorphine (CAI) has shown efficacy in the treatment of motor fluctuations but its place in the therapeutic arsenal remains poorly defined in terms of indication, acceptability and long-term tolerance. Indeed, few studies have been carried out with a follow-up greater than 12 months. The main objective was to assess the quality of life of Parkinson's disease (PD) patients treated with CAI. We also evaluate the effectiveness on the motor fluctuations, the long-term tolerance of this treatment with its causes of discontinuation and the treatment regimens used. METHODS: We conducted a retrospective study of 81 PD patients treated with CAI between April 2003 and June 2012. Data were collected from medical records. A repeated measures analysis of variance by the linear mixed model was used (significance level: 5%). RESULTS: In August 2012, 27/81 patients were still treated with CAI with a mean duration of 28 months, 46/81 discontinued CAI (9 precociously), and 8 were lost to view. We didn't show improvement in the quality of life nor efficacy of CAI on the UPDRS IV score (P=0.54) and dyskinesia score (P=0.95). The CGI score patient also reflects this result with a majority response suggesting no significant change with CAI. We observed relative good cognitive and psychiatric tolerance. Adverse events were frequent but often benign. The average (±SD) rate of apomorphine was 3.15±1.71 mg/h and the oral dopaminergic treatment was decreased by 37.8%. DISCUSSION: The results are consistent with the literature except for the lack of efficiency on motor fluctuations which may be due to the use of too small doses of apomorphine. This seems to be a leading cause of discontinuation of CAI, especially when it is associated with side effects or important constraints. For better efficiency on motor fluctuations, we recommend the use of apomorphine at higher doses to obtain an optimal continuous dopaminergic stimulation.

[Impulse control disorders in Parkinson's disease: A cohort of 35 patients]. / Troubles du contrôle des impulsions associés à la maladie de Parkinson : étude d'une cohorte de 35 patients.

INTRODUCTION: Impulse control disorders (ICDs) in Parkinson's disease (PD) are associated with dopamine agonist treatment. Although discontinuation of dopamine agonist is recommended, ICD management has not been precisely stated. The aims of the study were to describe demographic and clinical characteristics in a group of PD patients with ICDs and to evaluate the management of dopamine agonist treatment proposed to the same patients in order to treat the ICDs. METHODS: Thirty-five PD patients with ICD and 607 PD patients without ICD were studied. In the ICD group, demographic and clinical data were collected prospectively (ICD characteristics, motor and cognitive evaluation); demographic and clinical data were obtained retrospectively in the group without ICD. RESULTS: In the ICD group, the sex ratio was 2.9 (versus 1.2 in the absence of ICD; p<0.05), the mean age was 57.5 years (versus 66.9 years; p<0.01) and the mean age at PD onset was 48.3 years (versus 55.5 years; p<0.01). All ICD patients were receiving a dopamine agonist when the ICD started (versus 50.9 % of patients receiving a dopamine agonist in the absence of ICD; p<10(-6)). In mean, ICDs started 2.8 years before they were diagnosed. No particular dopamine agonist was associated with ICDs more frequently than the others. Discontinuation of the dopamine agonist was the treatment the more frequently associated with the recovery of ICDs (93.3 %). Dose lowering and the change of dopamine agonist resulted in complete regression of ICDs respectively in 9.1% and 33.3% of patients. CONCLUSION: Young age, male gender and young age at PD onset are frequent in PD patients developing ICDs, as already described in American or Asian cohorts. We highlighted a long diagnosis delay and confirmed the strong efficacy of dopamine agonist withdrawal.

[Classification of parkinsonian syndromes via factorial discriminant analysis of brain SPECT data]. / Intérêt de l'analyse factorielle discriminante pour classer les syndromes parkinsoniens à partir de la tomoscintigraphie d'émission monophotonique.

INTRODUCTION: The objective was to assess the value of single photon emission computerized tomography (SPECT) and factorial discriminant analysis (FDA) in the differential diagnosis of Parkinson's disease (PD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). PATIENTS AND METHODS: Sixty-two patients with clinical diagnoses of either CBD, PSP or PD were studied using brain HmPaO-SPECT. Thirteen pairs of regions of interest (ROIs) were drawn on the slices located 50mm and 90mm above the canthomeatal plane. Twenty-six uptake indices and 13 asymmetry indices were determined. FDA was performed in order to determine whether or not the patients could be classified into the correct clinical group on the basis of SPECT data alone. The most discriminant parameters were used to generate two predictive scores, which were tested in a second group of 15 patients. RESULTS: FDA of all 39 variables correctly classified all the patients. A subset of 10 variables was used to build predictive scores, which correctly classified 90% of PD patients, 100% of PSP patients and 86% of CBD patients. When tested in the validation group of 15 patients, these predictive scores correctly classified 87% of the individuals. The frontal medial, temporoparietal and parietal regions were the most discriminant. CONCLUSION: Using SPECT data alone, this study enabled us to distinguish between PD, PSP and CBD in patients with clear clinical presentations of the diseases in question. This novel, statistical approach provides reliable information. However, a prospective study dealing with de novo parkinsonian syndromes will be necessary.

Is the early-onset torsion dystonia (EOTD) linked to TOR1A gene as frequent as expected in France?

Early onset torsion dystonia are rare movement disorders. Molecular defect is known for only a subgroup, consisting of a unique and recurrent mutation in the TOR1A gene. We undertook a nationwide census of French TOR1A-mutation carriers and the assessment of clinical associated signs. Overall, 53 index cases and 104 relatives were studied and haplotypes linked to the mutation constructed. The previously reported Ashkenazi-Jewish haplotype was found in 11 families with the remainder carrying distinct haplotypes suggesting independent mutation events. This study demonstrates the scarcity of this disease in France with estimated disease frequency of 0.13:100,000 and mutation frequency of 0.17:100,000.

Seizure after use of almotriptan.

We report the case of a young woman who suffered from a seizure after use of almotriptan. There was a recurrence with ergotamine. We discuss possible link with susceptibility genes.

[Multi-infarct disorder presenting as corticobasal degeneration (DCB): vascular pseudo-corticobasal degeneration?]. / Infarctus cérébraux multiples se présentant comme une dégénérescence cortico-basale: pseudo dégénérescence cortico-basale vasculaire?

We report on five patients with a clinical presentation of corticobasal degeneration (CBD), including gradually progressive, asymmetric, L-DOPA-resistant parkinsonism associated variously with apraxia, focal action myoclonus, focal dystonia, cortical sensory loss and alien limb phenomenon. Some patients also presented an atypical CBD clinical history or signs - notably sudden onset. The disease was however not suggestive of another diagnosis. Magnetic resonance imaging of the brain revealed extensive vascular lesions. Only five similar cases have been published to our knowledge. Although we cannot exclude underlying CBD pathology, our cases illustrate the fact that multi-infarct pathology can masquerade as CBD or alter the clinical phenotype of the disease.

[High doses of botulinum toxin, from efficacy to safety: experimental data]. / Fortes doses de toxine botulinique, de l'efficacité au risque: données expérimentales.

Experimental studies in the animal have not been designed to specifically address the use of high doses of botulinum toxinum. However, it allows us to draw some very interesting findings. First, it has been showed that efficacy correlates to the dose, albeit up to a point beyond higher doses do not induce a greater benefit. Over this "ceiling" dose, the risk of migration outside the targeted muscle increases. The systemic risk is superior to the local risk. The efficacy could differ according to the number of injected muscles, and according to the type of toxin. What has been observed in the animals tend to be confirmed in human, despite precise studies are still lacking. Thus, experimental data support our daily clinical experience and provide us some very useful informations when high doses are injected. They especially help us to keep in mind the systemic risk which is, most of the time, unclear in our daily practice.

Extended vs. brief intermittent access to palatable food differently promote binge-like intake, rejection of less preferred food, and weight cycling in female rats.

BACKGROUND: Palatable food access promotes obesity leading some to diet. Here, we modeled the roles of duration, intermittency and choice of access in bingeing, escalation of daily intake, and underacceptance of alternatives. METHOD: Female rats with ("Choice") or without continuous chow access, received chow or continuous (Chocolate), intermittent (MWF) long (24h, Int-Long), or intermittent short (30min, Int-Short) access to a sucrose-rich, chocolate-flavored diet (CHOC). RESULTS: Int-Long rats showed cycling body weight; they overate CHOC, had increased feed efficiency on access days and underate chow and lost weight on non-access days, the latter correlating with their reduced brown fat. Int-Short rats had the greatest 30-min intake upon CHOC access, but did not underaccept chow or weight cycle. Individual vulnerability for intermittent access-induced feeding adaptations was seen. Continuous access rats gained fat disproportionate, but in direct relation, to their normalized energy intake and persistently underaccepted chow despite abstinence and return to normal weight. Abstinence reduced the binge-like CHOC intake of Int-Short rats and increased that of continuous access rats, but not to levels associated with intermittent access history. Choice increased daily CHOC intake under Continuous access and binge-like intake under Int-Short access. CONCLUSIONS: Intermittency and duration of past access to palatable food have dissociable, individually-vulnerable influences on its intake and that of alternatives. With extended access, daily intake reflects the palatability of available food, rather than metabolic need. Ongoing restrictedness of access or a history of intermittency each drive binge-like intake. Aspects of palatable food availability, similar and different to drug availability, promote disordered eating.

Similarity of folate receptor expression in UMSCC 38 cells to squamous cell carcinoma differentiation markers.

BACKGROUND: The folate receptor is a 38 to 39 kd glycoprotein attached to the cell membrane via a glycosylphosphatidylinositol anchor. It serves as the initiation point for receptor-coupled transport of folate in a process known as potocytosis. The receptor is overproduced by a number of malignant cell lines in vitro and in a large percentage of ovarian and uterine malignancies. Immunohistochemistry has shown the receptor to be expressed primarily in normal differentiated tissues such as choroid plexus, placenta, thyroid, and kidney. The receptor gene(s) has been mapped to the human chromosomal locus 11q13. PURPOSE: In order to better understand regulation of the synthesis of the receptor, we studied the expression and accumulation of the folate receptor in UMSCC 38 cells, a human malignant squamous cell carcinoma line with a karyotype that is amplified at the folate receptor gene locus. METHODS: Western blot analysis of octylglucoside-solubilized cell membranes was used to analyze expression of several proteins by UMSCC 38 cells grown in culture under varied conditions. Bands on autoradiographs, representing electrophoresed proteins detected by indirect antibody labeling and an enhanced chemiluminescence reaction, were quantitated by densitometry. RESULTS: The expression of the folate receptor was found to increase approximately fourfold as UMSCC 38 cells were grown to higher cell densities over increasing lengths of time, ranging from 3 to 9 days, in culture. The expression of K1 keratin protein, a known marker of differentiation in squamous cell carcinomas, was elevated to a similar degree (3.2-fold) between day 5 and day 9 in cultures of these cells. Expression of folate-receptor protein in UMSCC 38 cells was also found to be reduced approximately 10-fold when cells were exposed to 1 microM retinoic acid for 48 hours and increased approximately eightfold after a 5-day exposure to 3 microM hydrocortisone. CONCLUSIONS: We present evidence that synthesis of the folate receptor in UMSCC 38 cells is affected by the same pathway that changes the expression of some markers of differentiation in squamous cell carcinomas. IMPLICATIONS: The fact that folate receptor expression in these malignant cells can be manipulated using retinoids and steroids suggests that these hormones could modulate the efficiency of folate and antifolate uptake via the folate receptor and may enhance the usefulness of the receptor as a target for immunotherapy.

[Can meningoencephalitis be caused by Chlamydiae pneumoniae?]. / Méningoencéphalite à Chlamydiae pneumoniae?

INTRODUCTION: Meningoencephalitis attributed to Chlamydiae pneumoniae has rarely been reported in the literature. OBSERVATION: We describe the case of a 21-year-old-man admitted for a meningeal syndrome and fever associated with respiratory symptoms and a temporal syndrome. Even though the clinical presentation and certain serological results suggested Chlamydiae infection, some of the biological data raised the possibility of Epstein Barr Virus infection. Intravenous fluoroquinolone therapy led to a successful outcome. CONCLUSION: Meningoencephalitis associated with non neurological symptoms, especially respiratory symptoms, is suggestive of Chlamydia pneumoniae infection. A broad spectrum antibiotic should be prescribed.

Vascular aphasias: main characteristics of patients hospitalized in acute stroke units.

BACKGROUND AND PURPOSE: Aphasia is frequent in stroke patients and is associated with poor prognosis. However, characteristics and determinants of vascular aphasias remain controversial. The aim of this study was to evaluate aphasia characteristics at the acute stage in patients admitted to a stroke unit. METHODS: The study was performed in 308 patients consecutively assessed with a standardized aphasia battery. RESULTS: Aphasia was observed in 207 patients; global and nonclassified aphasias accounted for 50% of aphasic syndromes at the acute stage, whereas classic aphasias (Wernicke's, Broca's, transcortical, and subcortical aphasias) were less frequent. Age differed across aphasic syndromes in ischemic stroke patients only; patients with conduction aphasia were younger, and patients with subcortical aphasia were older. Sex did not significantly differ across aphasic syndromes. The presence of a previous stroke was more frequent in nonclassified aphasia. CONCLUSIONS: This study shows (1) that vascular aphasias are frequently severe or nonclassic at the acute stage, a finding explained in part by the presence of a previous stroke; (2) that the age effect is due mainly to its influence on infarct location; and (3) that the main determinant of aphasia characteristics is lesion location.

The anatomy of aphasia revisited.

OBJECTIVE: To determine lesion locations associated with the various types of aphasic disorders in patients with stroke. BACKGROUND: The anatomy of aphasia has been challenged by several recent studies. Discrepancies are likely to be due to methodologic issues. METHODS: We examined 107 patients with a standardized aphasia battery and MRI. Three examiners blinded to the clinical data rated signal abnormalities in 69 predetermined regions of interest. The statistical procedure used classification tree testing, which selected regions associated with each aphasic disorder. RESULTS: 1) Nonfluent aphasia depended on the presence of frontal or putaminal lesions; 2) repetition disorder on insula-external capsule lesions; 3) comprehension disorder on posterior lesions of the temporal gyri; 4) phonemic paraphasia on external capsule lesions extending either to the posterior part of the temporal lobe or to the internal capsule; 5) verbal paraphasia on temporal or caudate lesions; and 6) perseveration on caudate lesions. These analyses correctly classified 67% to 94% of patients. CONCLUSIONS: Lesion location is the main determinant of aphasic disorders at the acute stage. Most clinical-radiologic correlations supported the classic anatomy of aphasia.

[Nodular lymphoid hyperplasia of the small bowel with IgA deficiency and hemolytic anemia (author's transl)]. / Hiperplasia nodular linfoide del intestino delgado con déficit de IgA y anemia hemolítica.

The syndrome of nodular lymphoid hyperplasia of the small bowel with hypogammaglobulinemia is one of the hypogammaglobulinemic enteropathies. Chronic diarrhea and malabsorption are the most characteristic features of this disease, and they are frequently associated to hypogammaglobulinemia of various types (acquired, congenital non sex-linked) and to selective IgA deficiency. The immunological deficiency gives rise to the more characteristic features of the disease, namely: a) hypogammaglobulinemia; b) respiratory infections and dental caries; c) Giardia lamblia infestation of the small bowel; d) the characteristic radiological features; and, e) the histological aspect of the intestinal mucosa with absence of plasma cells. Periodical follow-up is needed because of the increased incidence of tumors in immunological deficiency states. A new case of nodular lymphoid hyperplasia associated to hemolytic anemia and granulomatous hepatitis is reported, and its possible pathogenesis is discussed.