Parental use and acceptance of an accessible, commercially available intraoral camera for teledentistry in their children

PURPOSE

The potential of combining teledentistry and engaging parents as underutilised resources to monitor paediatric dental health was emphasised during the COVID-19 pandemic and remains underexplored. This study aims to assess parental acceptance and use of a commercially available intraoral camera (IOC) for effective remote monitoring.

METHODS

47 child-parent dyads, where the parent was the main caregiver and the child was treated under general anaesthesia for early childhood caries, were recruited. Caregivers were trained to image their child's teeth on a commercially available IOC. Subsequently, submitted images were reviewed asynchronously by dentists for image quality, presence of dislodged fillings, abscesses, cavitation, and oral hygiene. Post-surgery monitoring was performed using teledentistry at 1 and 2 months and in-person at 4 months. A modified Telehealth Usability Questionnaire (TUQ) was used to record caregiver acceptance for study procedures.

RESULTS

A mean TUQ of 6.09 out of 7 was scored by caregivers. Caregiver-reported issues were limited to problems with technique and child uncooperativeness. The number of clear images during the second teledentistry review was improved compared to the first (p = 0.007). 68% of children liked having images of their teeth taken.

CONCLUSION

This study supports the feasibility of using an IOC as a clinically appropriate avenue for teledentistry with a high level of caregiver-child acceptance.

Osteoporosis identification among previously undiagnosed individuals with vertebral fractures

Because osteoporosis is under-recognized in patients with vertebral fractures, we evaluated characteristics associated with osteoporosis identification. Most patients with vertebral fractures did not receive evaluation or treatment for osteoporosis. Black, younger, and male participants were particularly unlikely to have had recognized osteoporosis, which could increase their risk of negative outcomes.

INTRODUCTION

Vertebral fractures may be identified on imaging but fail to prompt evaluation for osteoporosis. Our objective was to evaluate characteristics associated with clinical osteoporosis recognition in patients who had vertebral fractures detected on their thoracolumbar spine imaging reports.

METHODS

We prospectively identified individuals who received imaging of the lower spine at primary care clinics in 4 large healthcare systems who were eligible for osteoporosis screening and lacked indications of osteoporosis diagnoses or treatments in the prior year. We evaluated characteristics of participants with identified vertebral fractures that were associated with recognition of osteoporosis (diagnosis code in the health record; receipt of bone mineral density scans; and/or prescriptions for anti-osteoporotic medications). We used mixed models to estimate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

A total of 114,005 participants (47% female; mean age 65 (interquartile range: 57-72) years) were evaluated. Of the 8579 (7%) participants with vertebral fractures identified, 3784 (44%) had recognition of osteoporosis within the subsequent year. In adjusted regressions, Black participants (OR (95% CI): 0.74 (0.57, 0.97)), younger participants (age 50-60: 0.48 (0.42, 0.54); age 61-64: 0.70 (0.60, 0.81)), and males (0.39 (0.35, 0.43)) were less likely to have recognized osteoporosis compared to white participants, adults aged 65 + years, or females.

CONCLUSION

Individuals with identified vertebral fractures commonly did not have recognition of osteoporosis within a year, particularly those who were younger, Black, or male. Providers and healthcare systems should consider efforts to improve evaluation of osteoporosis in patients with vertebral fractures.

Observing separate spin and charge Fermi seas in a strongly correlated one-dimensional conductor

An electron is usually considered to have only one form of kinetic energy, but could it have more, for its spin and charge, by exciting other electrons? In one dimension (1D), the physics of interacting electrons is captured well at low energies by the Tomonaga-Luttinger model, yet little has been observed experimentally beyond this linear regime. Here, we report on measurements of many-body modes in 1D gated wires using tunneling spectroscopy. We observe two parabolic dispersions, indicative of separate Fermi seas at high energies, associated with spin and charge excitations, together with the emergence of two additional 1D "replica" modes that strengthen with decreasing wire length. The interaction strength is varied by changing the amount of 1D intersubband screening by more than 45%. Our findings not only demonstrate the existence of spin-charge separation in the whole energy band outside the low-energy limit of the Tomonaga-Luttinger model but also set a constraint on the validity of the newer nonlinear Tomonaga-Luttinger theory.

A case of successfully managed pregnancy in a patient with complex cyanotic congenital heart disease

Medical advances have increased survival of patients with congenital heart disease. However, cardiac disease in pregnancy carries significant maternal and fetal risks, posing enormous challenges to obstetricians. Cyanotic congenital heart disease is associated with maternal complications such as arrhythmias, thromboembolic events and death. Fetal complications include small for gestational age, miscarriage and prematurity. Cyanotic congenital heart disease patients who continue their pregnancies require holistic multidisciplinary team care with early and coordinated planning for delivery. Management of such patients include early counseling regarding pregnancy-associated risks, close monitoring of their cardiac function and regular scanning for fetal assessment. Choice of anesthesia for these patients requires meticulous planning to achieve a favorable balance between systemic and pulmonary vascular resistance, ensuring minimal change in right-to-left shunting. We report a case of a successfully managed pregnancy in a patient with complex congenital heart disease and a single ventricle of left ventricle morphology.

Past, present and future of Barrett's oesophagus

Barrett's oesophagus is a condition which predisposes towards development of oesophageal adenocarcinoma, a highly lethal tumour which has been increasing in incidence in the Western world over the past three decades. There have been tremendous advances in the field of Barrett's oesophagus, not only in diagnostic modalities, but also in therapeutic strategies available to treat this premalignant disease. In this review, we discuss the past, present and future of Barrett's oesophagus. We describe the historical and new evolving diagnostic criteria of Barrett's oesophagus, while also comparing and contrasting the British Society of Gastroenterology guidelines, American College of Gastroenterology guidelines and International Benign Barrett's and CAncer Taskforce (BOBCAT) for Barrett's oesophagus. Advances in endoscopic modalities such as confocal and volumetric laser endomicroscopy, and a non-endoscopic sampling device, the Cytosponge, are described which could aid in identification of Barrett's oesophagus. With regards to therapy we review the evidence for the utility of endoscopic mucosal resection and radiofrequency ablation when coupled with better characterization of dysplasia. These endoscopic advances have transformed the management of Barrett's oesophagus from a primarily surgical disease into an endoscopically managed condition.

Hierarchy of modes in an interacting one-dimensional system

Studying interacting fermions in one dimension at high energy, we find a hierarchy in the spectral weights of the excitations theoretically, and we observe evidence for second-level excitations experimentally. Diagonalizing a model of fermions (without spin), we show that levels of the hierarchy are separated by powers of R^{2}/L^{2}, where R is a length scale related to interactions and L is the system length. The first-level (strongest) excitations form a mode with parabolic dispersion, like that of a renormalized single particle. The second-level excitations produce a singular power-law line shape to the first-level mode and multiple power laws at the spectral edge. We measure momentum-resolved tunneling of electrons (fermions with spin) from or to a wire formed within a GaAs heterostructure, which shows parabolic dispersion of the first-level mode and well-resolved spin-charge separation at low energy with appreciable interaction strength. We find structure resembling the second-level excitations, which dies away quite rapidly at high momentum.

Inter-fraction prostate motion during intensity-modulated radiotherapy for prostate cancer

INTRODUCTION

This study aimed to analyse the inter-fraction prostate motion and setup error during intensity-modulated radiotherapy for prostate cancer at the National Cancer Centre Singapore.

METHODS

Gold seeds were implanted as fiducial markers. Daily portal films were taken and displacements of the gold seeds from the isocentre in each axis were recorded. Random and systematic errors were used to derive a margin recipe for each axis based on the van Herk formula.

RESULTS

1,077 fractions from 36 patients were analysed. 89.8 percent, 85.2 percent and 83.6 percent of the setup errors were within +/- 2 mm for the right-left (RL), superior-inferior (SI) and anterior-posterior (AP) axes, respectively. The population systematic errors were 0.71 mm, 0.84 mm and 0.87 mm; the population random errors were 1.32 mm, 1.59 mm and 1.70 mm; the overall population mean setup errors were -0.14 (range -2.27 to 1.15) mm, 0.11 (range -2.32 to 1.69) mm and 0.08 (range -1.33 to 1.46) mm; and the van Herk margin recipes were 2.69 mm, 3.22 mm and 3.37 mm for the RL, SI and AP axes, respectively.

CONCLUSION

The setup errors and inter-fraction prostate movements were small. Gold seed implantation is a feasible and easy method of verifying the prostate position.

A century of medical students' activities (Medical College Union/Medical Society)

The Medical College Union (MCU) was formed in 1922 to encourage and promote comradeship and public spirit amongst the students of King Edward VII College of Medicine. The Medical College Union Society was founded and held its first meeting on 31 July 1936. However, the Annual Report for 1940-42 made no reference to the Society at all and it was hence considered to cease to exist as an official body. The Medical Society (Medsoc), headed by Mr Goon Sek Mun, was formed in 1949 and it organised various activities and events for the faculty. Some of these are still being held annually today, with the addition of several others and phasing out of some. These were organised by the individual subgroups in the Medical society, like the Social, Welfare, Sports and Publications committees. The Medsoc also acts as the students' voice in conveying their opinions to the administration and the Dean. With the expected advent of a new medical school in Singapore--a postgraduate one in the Outram Campus, the medical student community in Singapore will only get larger. There should be a role for Medsoc to foster closer ties between the student communities.

A clinical report about an unusual occurrence of post-anesthetic tongue swelling

Dentures are routinely removed from the oral cavity before general anesthetic procedures. They are only reinserted much later when the patient returns to the room. This clinical report describes an edentulous patient who developed acute tongue swelling from venous congestion as a result of tongue recovery from general anesthesia. Her complete dentures were used to separate the residual ridges during the recovery period and relieved the congestion. Denture insertion increased the height and volume of the oral cavity, which reduced pressure on the tongue, preventing a cycle of tongue compression, congestion, and swelling. This unusual complication suggests that it may be prudent for the edentulous patient to be accompanied by their dentures in the perioperative period.

Comparison of patient-controlled sedation with propofol and alfentanil for third molar surgery--preliminary results of a pilot study

Propofol and alfentanil are commonly used for sedation and pain control. A preliminary study to compare the usefulness of these drugs was carried out in ten healthy patients requiring bilateral wisdom tooth surgery. The operations were done in two appointments with the patient receiving a different drug on each occasion. Anxiety levels were recorded on visual analogue scales pre and post-operatively. Both agents caused a decrease in anxiety scores, with propofol causing a more significant reduction. Vomiting and nausea with alfentanil was noted in three patients. Propofol also had an amnesic effect which alfentanil did not have. In conclusion, propofol would appear to be the drug of choice within the limitations of this pilot study.

Case reports: the use of intermaxillary screws to achieve intermaxillary fixation in the treatment of mandibular fractures

INTRODUCTION

Treatment of mandibular fractures commonly involves the use of arch bars in temporary maxillo-mandibular fixation (also called intermaxillary fixation) to aid bone plating, for the postoperative application of light elastic traction to correct minor occlusal discrepancies and intermaxillary fixation for post reduction immobilisation. The purpose of this paper is to describe a quick and simple alternative for intermaxillary fixation.

CLINICAL PICTURE

Three cases of mandibular fractures are presented to demonstrate the use of intermaxillary screws instead of conventional arch-bar wiring.

TREATMENT

Two cases were treated with closed reduction methods while the other case was treated with open reduction.

OUTCOME

Subsequent fracture healing was not compromised using this technique.

CONCLUSIONS

With careful case selection, successful treatment outcome may be achieved using this time-saving and technically simple procedure. Some of the advantages and disadvantages of the intermaxillary screws are discussed.

Role of the cerebrovascular and metabolic responses in the delayed phases of injury after transient cerebral ischemia in fetal sheep

BACKGROUND AND PURPOSE

Perinatal hypoxic-ischemic injuries can trigger a cascade of events leading to delayed deterioration and cell death several hours later. The objective of this study was to characterize the cerebral blood flow responses and the changes in extracellular glucose and lactate during the delayed phases of injury and to determine their relationships with the pathophysiological events after hypoxic-ischemic injury.

METHODS

Two groups of near-term chronically instrumented fetal sheep were subjected to 30 minutes of cerebral hypoperfusion. In the first group, regional cerebral blood flow was measured over the next 24 hours with radiolabeled microspheres. In the second, cortical extracellular glucose and lactate were measured by microdialysis. Parietal electrocorticographic activity and cortical impedance were recorded continuously in both groups, and the extent of neuronal loss was determined histologically at 72 hours after injury.

RESULTS

Cerebral blood flow was transiently impaired in the cortex during reperfusion, whereas during the delayed phase, there was a marked increase in cerebral blood flow. The severity of cortical neuronal loss was related to the degree of hypoperfusion in the immediate reperfusion period and inversely related to the magnitude of the delayed hyperperfusion. Cortical extracellular lactate was elevated after injury, and both glucose and lactate secondarily increased during the delayed phase of injury.

CONCLUSIONS

The delayed phase is accompanied by a period of hyperperfusion that may protect marginally viable tissue.

Brain acidosis, cerebral blood flow, capillary bed density, and mitochondrial function in the ischemic penumbra

Within the ischemic penumbra, there is a heterogeneous development of cortical intracellular acidosis that is associated with selective neuronal injury. This experiment, which used a rabbit model of moderate focal cerebral ischemia, examined the time course for changes in intracellular brain pH, cortical blood flow, capillary bed density, and mitochondrial function in the ischemic penumbra. After cortical annotation of regions of intracellular acidosis in the ischemic penumbra, the animals underwent transcardiac carbon black perfusion for measurement of capillary bed density. Analysis of variance and Pearson's correlation coefficients were used to determine the relationship between capillary bed density, brain intracellular pH, mitochondrial function, and cortical blood flow. Thirty minutes after the onset of ischemia, cortical blood flow declined from 46+/-2 to 22+/-1 mL/100gm/min (P<.01) in all groups. The overall cortical intracellular brain pH measured 6.78+/-.01 compared with a preischemic value of 6.98+/-.01 (P<.05). Within this moderately ischemic cortex, there were small regions (1,000 to 45,000 mum(2)) of increased acidosis, meauring 6.68+/-.01, not associated with focal changes in cortical blood flow, occurring within 15 minutes of ischemia and persisting throughout the ischemic period. Capillary bed density progressively declined with ongoing ischemia occurring after the development of acidosis. For example, capillary bed density in preischemic controls was 338+/-6/mm(2), whereas after 1 hour of ischemia, it measured 147+/-12/mm(2), at 3 hours 97+/-23/mm(2), and at 6 hours 92+/-16/mm(2). Mitochondrial function was reduced coinciding with the decrease in capillary bed density. These data support the hypothesis that cortical acidosis in the ischemic penumbra facilitates the development of perfusion defects that subsequently lead to mitochondrial dysfunction.

Aetiology and distribution of mandibular fractures in the National University Hospital, Singapore

Sixty-seven consecutive mandibular fractures treated mainly in 1998 were surveyed retrospectively. Treatment was performed at the National University Hospital, Singapore. Males outnumbered females by 5:1, with Chinese the commonest racial group involved (56.7%). Most patients were between 20 and 29 years of age. Road traffic accidents formed the largest proportion (61.2%) followed by industrial accidents and assaults. The symphyseal and parasymphyseal regions were most commonly fractured (46.5%). Almost a third of the patients sustained other facial fractures. Treatment was commonly administered within one to two days of discovery of the fracture and open reduction was the treatment plan of choice in 79.1% of the time. Discussion on how aetiology affects the fracture pattern in Singapore is carried out.

Effects of glucose and PaO2 modulation on cortical intracellular acidosis, NADH redox state, and infarction in the ischemic penumbra

BACKGROUND AND PURPOSE

During focal cerebral ischemia, the ischemic penumbra or border-zone regions of moderate cortical blood flow reductions have a heterogeneous development of intracellular cortical acidosis. This experiment tested the hypotheses that (1) this acidosis is secondary to glucose utilization and (2) this intracellular acidosis leads to recruitment of potentially salvageable tissue into infarction.

METHODS

Brain pHi, regional cortical blood flow, and NADH redox state were measured by in vivo fluorescent imaging, and infarct volume was assessed by triphenyltetrazolium chloride histology. Thirty fasted rabbits divided into 6 groups of 5 each were subjected to 4 hours of permanent focal ischemia in the presence of hypoglycemia ( approximately 2.8 mmol/L), moderate hyperglycemia ( approximately 11 mmol/L), and severe hyperglycemia (>28 mmol/L) under either normoxia or moderate hypoxia (PaO2 approximately 50 mm Hg).

RESULTS

Preischemic hyperglycemia led to a more pronounced intracellular acidosis and retardation of NADH regeneration than in the hypoglycemia groups under both normoxia and moderate hypoxia in the ischemic penumbra. For example, 4 hours after ischemia, brain pHi in the severe hyperglycemia/normoxia group measured 6.46, compared with 6.84 in the hypoglycemia/normoxia group (P<0.01), and NADH fluorescence measured 173% compared with 114%. Infarct volume in the severe hyperglycemia/normoxia group measured 35.1+/-6.9% of total hemispheric volume, compared with 13.5+/-4.2% in the hypoglycemia/normoxia group (P<0.01).

CONCLUSIONS

Hyperglycemia significantly worsened both cortical intracellular brain acidosis and mitochondrial function in the ischemic penumbra. This supports the hypothesis that the evolution of acidosis in the ischemic penumbra is related to glucose utilization. Furthermore, the observation that hypoglycemia significantly decreased infarct size supports the postulate that cortical acidosis leads to recruitment of ischemic penumbra into infarction.

Accumulation of cytotoxins during the development of seizures and edema after hypoxic-ischemic injury in late gestation fetal sheep

Several hours after an hypoxic-ischemic injury to the developing brain, hyperemia, then seizures, edema, and infarction can develop. The roles of nitric oxide (NO) synthesis and excitotoxin accumulation during these later phases of injury are not known. The time course of extracellular levels of amino acids within the parasagittal parietal cortex were measured with microdialysis during and for 3 d after 30 min of cerebral ischemia in nine chronically instrumented near-term fetal sheep (119-133 d). Cortical electroencephalographic (EEG) activity and extracellular space (ECS) were quantified simultaneously with real-time spectral analysis and cortical impedance measurements, respectively. Amino acid concentrations were measured using HPLC. During ischemia, citrulline (by-product of NO synthesis), glutamate, glycine, and gamma-aminobutyric acid (GABA) concentrations rose to 147 +/- 18%, 180 +/- 20%, 290 +/- 50% and 4800 +/- 1300% of baseline respectively (p < 0.05). The excitotoxic index ([glutamate] x [glycine]/[GABA]) decreased to 15 +/- 8%. Upon reperfusion, the cytotoxic edema and amino acid accumulation largely resolved within 1 h, and the EEG was depressed. Citrulline began to rise again by 4 h (p < 0.05), reaching a maximum (273 +/- 21%) at 32 +/- 2 h. Seizure activity developed at 7 +/- 2 h, and impedance plus the excitotoxic index then rose progressively and peaked at 32 +/- 2 h (480 +/- 170%). At 72 h, there was severe neuronal loss and laminar necrosis within the parasagittal cortex. These data suggest that, several hours after a severe hypoxicischemic injury, NO synthesis increased, then seizures arose, and edema developed concomitantly with the accumulation of excitotoxins.

Oro-facial pain distribution in the Singapore Armed Forces: a pilot study

The purpose of the study was to obtain information on the pain distribution in 140 consecutive patients referred to a Singapore Armed Forces (SAF) Temporomandibular Disorders (TMD) and Craniofacial pain clinic from January 1992 to April 1994 via questionnaire, oral history and clinical examination. A cross-sectional study of 130 patients in the general military population was also done to serve as a control and to obtain initial data on the prevalence of signs and symptoms of TMD in the SAF. The control was age and sex matched with the TMD patient sample. The data showed that the "TMD patient" infrequently presented with temporomandibular joint pain alone. Neck pain, shoulder pain, ear ache and headaches were found quite frequently in addition to masticatory muscle tenderness and should be checked for in any TMD patient. Initial findings support the recommendation that the routine palpation of the styloid regions be included in any clinical screening protocol for patients presenting with head, neck and oro-facial pains. A history of macrotrauma and parafunctional habits were also important. Interesting observations relating to the TMD patients in the SAF are briefly described and discussed and there is a need to further explore the correlation between certain SAF vocations and TMD.

Flunarizine, a calcium channel antagonist, is partially prophylactically neuroprotective in hypoxic-ischemic encephalopathy in the fetal sheep

Calcium antagonist therapy has been reported to reduce neuronal death after hypoxia-ischemia; however, its potential use in prenatal hypoxic-ischemic events has received little attention. We examined the effect of pretreatment with flunarizine in chronically instrumented late gestation fetal sheep subjected to 30 min of cerebral ischemia. Eight fetuses were given 0.11 mmol (45 mg) of flunarizine over 2 h preischemia (high dose), 10 were given 0.07 mmol (30 mg) over 3 h preischemia (low dose), 17 were given nothing (ischemia controls), and 5 received neither the ischemic insult nor any treatment (sham controls). The fetal electrocorticogram was monitored for 3 d postinsult. Histologic outcome was quantified after 72 h. Low-dose, but not high-dose, flunarizine therapy was associated with an overall reduction in cerebral damage (p < 0.01), a greater final electrocorticogram intensity, and a reduction in the incidence of seizures (p < 0.02) compared with ischemia controls. High-dose, but not low-dose, flunarizine was associated with a significant acute mortality and a decrease in fetal blood pressure (p < 0.05) at the time of occlusion, although there was no effect on the initial hypertensive response to occlusion. These observations suggest that flunarizine is partially neuroprotective when given before severe global ischemia in utero, but that its hypotensive effects make it unsuitable for prophylactic administration in utero.

Monosialoganglioside GM1 treatment after a hypoxic-ischemic episode reduces the vulnerability of the fetal sheep brain to subsequent injuries

OBJECTIVE

A transient hypoxic-ischemic episode can markedly sensitize regions of the fetal brain, particularly the striatum, to further insults occurring in close succession. The purpose of this study was to determine whether ganglioside GM1 given to the fetus after a hypoxic-ischemic episode can counteract this sensitization and protect against subsequent insults.

STUDY DESIGN

Chronically instrumented near-term fetal sheep (119 to 133 days) were subjected to three 10-minute episodes of reversible cerebral ischemia at 1-hour intervals. Six were given 30 mg/kg ganglioside GM1 through the umbilical vein, commencing immediately after the release of the occluder, over the next 2 hours, followed by a continuous infusion of 30 mg/kg/day over 60 hours after ischemia; these were compared with seven vehicle-treated controls. The time course of electrocorticographic activity and cytotoxic edema within the parasagittal cortex were determined with real-time spectral analysis and continuous impedance measurements, respectively. The degree and distribution of neuronal death was assessed histologically 72 hours later.

RESULTS

Ganglioside GM1 improved recovery of primary edema and markedly reduced histologic damage (p < 0.001), particularly in the striatum, hippocampus, and cortex. At 72 hours after ischemia electrocorticographic activity had returned to normal in the ganglioside GM1-treated group but was still depressed (p < 0.001) in the control group.

CONCLUSION

These results showed that ganglioside GM1 treatment initiated immediately after a transient hypoxic-ischemic episode stabilized membrane function and markedly improved neuronal outcome after subsequent insults, suggesting its potential therapeutic value in acute situations of repeated hypoxia-ischemia in the perinatal period.

Pretreatment with monosialoganglioside GM1 protects the brain of fetal sheep against hypoxic-ischemic injury without causing systemic compromise

The purpose of this study was to determine whether prophylaxis with monosialoganglioside GM1 can protect the fetus from hypoxic-ischemic encephalopathy in utero. Because some protective strategies can compromise the fetus, the effect of GM1 treatment on metabolic status and blood pressure was also evaluated. Chronically instrumented near-term fetal sheep (119-133 d) were subjected to 30 min of severe cerebral ischemia. Six were given 30 mg/kg GM1 through the umbilical vein 2 h before insult followed by continuous infusion of 30 mg/kg/d over the next 60 h, and these were compared with seven vehicle-treated control sheep. The time course of electrocorticographic activity and cytotoxic edema within the parasagittal cortex were determined with real-time spectral analysis and continuous impedance measurements, respectively. Histologic outcome was assessed 72 h later. Pretreatment with GM1 improved recovery of primary edema, reduced the duration of epileptiform activity (15 +/- 2 versus 31 +/- 5 h; p < 0.05) and the magnitude of secondary edema (p < 0.05). At 72 h, histologic damage was reduced, particularly in the cortex (p < 0.05) and hippocampus (p < 0.01), and residual electrocorticographic activity was increased in the GM1-treated group (-5 +/- 1 versus -9 +/- 3 dB, p < 0.01). GM1 infusion did not alter arterial blood pressure or metabolic status. These results indicate that GM1 can protect the fetal brain against hypoxic-ischemic injury without causing hypotension or metabolic compromise.

Suppression of postischemic epileptiform activity with MK-801 improves neural outcome in fetal sheep

To determine the effect of suppression of epileptiform activity that develops after hypoxic-ischemic injury in the immature brain, chronically instrumented near-term fetal sheep (119-133 days) were subjected to 30 minutes of complete cerebral ischemia: 6 were given a 0.3-mg/kg bolus of MK-801 at 6 hours after the insult followed by continuous infusion of 1 mg/kg over the next 36 hours, and were compared to 6 control sheep. Electrocorticographic activity and edema within the parasagittal region of the cortex were quantified with real-time spectral analysis and impedance measurements, respectively. Histological outcome was assessed 72 hours later. The intense epileptiform activity seen from 9 +/- 2 to 30 +/- 3 hours in the control group was completely suppressed in the MK-801-treated group. The onset of secondary cortical edema was delayed from 9.4 +/- 1.1 hours to 14.8 +/- 0.7 hours (p < 0.01). Neuronal damage was reduced, particularly in the lateral cortex and hippocampus (p < 0.05). Infarction of the parasagittal cortex was not prevented. These results suggest that N-methyl-D-aspartate-mediated epileptiform activity that develops after a global hypoxic-ischemic insult worsens neuronal outcome in the immature brain.

Additive inheritance of resistance to pod rot caused by Phytophthora palmivora in cocoa

Quantitative inheritance of resistance to Phytophthora pod rot (Ppr) was studied in cocoa hybrid progeny from 12 Trinitario x Amazonian crosses and their reciprocal crosses. The crossing scheme was similar to a factorial design. Disease was assessed by the number and percentage of infected pods on each tree. Highly significant differences due to general combining abilities (GCA) were obtained for all characters, except for the GCA of Trinitario on total pod production. Differences for specific combining ability (SCA) were not significant for all characters. There were no significant differences between reciprocal crosses. The Trinitario clone K82 provided the only source for the hybrid progenies of strong Ppr resistance to the hybrid progenies, while K20 provided moderate resistance. Other parental clones - KA2-101, KA5-201, KEE 2, KEE 5, and KEE 52 - produced progenies which were susceptible to Ppr. It is evident that resistance to Ppr in cocoa is inherited additively. Maternal and cytoplasmic effects were assumed to have no influence on inheritance of resistance. It is also concluded that resistance to Ppr of the kind shown by K82 is likely to be horizontal resistance. Breeding for high-yielding cultivars combined with Ppr resistance is the most effective way of controlling Ppr of cocoa on the crops of growers with small holdings in Papua New Guinea.

Interaction between alfalfa cultivars and Rhizobium strains for nitrogen Fixation

Two experiments were conducted in the greenhouse to study the interaction between alfalfa cultivars (Medicago sativa L. and M. falcata L.) and strains of Rhizobium meliloti Dang. for acetylene reduction rate, plant height and dry weights of shoot, root and whole plant. Fifteen alfalfa cultivars were inoculated with 10 strains of Rhizobium in Experiment I. Variance component analysis revealed that more than 30% of the total variance was due to alfalfa cultivars for acetylene reduction rate and 26% was accounted for by Rhizobium strains. More than 36% of the total variation was attributed to the interaction between alfalfa cultivars and Rhizobium strains for this character. Twenty-five host cultivars and 11 Rhizobium strains were included in Experiment II. The results also showed that the interaction of alfalfa cultivars and Rhizobium strains contributed the largest portion of the total variation for dry weights of shoot, root and whole plant and acetylene reduction rate. The results clearly demonstrated that the non-additive effects were the major component of variation for these characters associated with nitrogen fixation in alfalfa. Therefore, an effective way of improving nitrogen fixation in alfalfa is to select for a favourable combination of specific Rhizobium strains and alfalfa cultivars.

Dissolution rates of silicate cements

The literature relating to the dissolution of the silicate cements is reviewed, including the methodology, intrinsic factors relating to composition and method of mixing, curing etc. and extrinsic factors, i.e. the medium, pH, ionic strength etc. to which the sample of cement is exposed. New experimental data is shown relating the dissolution rate to solution composition and ionic strength. It is seen that samples of silicate cement can take up phosphate from solution as well as releasing this species and a dissolution process based on a reversible equilibrium is advanced. Also considered are the effects of sample volume:area ratio and the effect of agitation.

Combining ability analyses of stability parameters and forage yield in smooth bromegrass

Twenty-one progenies of smooth bromegrass (Bromus inermis Leyss.) from a 7 X 7 half diallel cross, with their parents, were evaluated for three years at four locations in Alberta for the genetic variation of stability in expression of their annual yield. The linear response and deviation from linear response for each genotype were the two stability parameters considered, together with mean performance in the evaluation of each genotype. Four high yielding genotypes, namely 12, 13, 16, and 26, had general adaptability, while genotype 23 was especially suited to a poor environment. Combining ability analysis showed that general combining ability (GCA) and specific combining ability (SCA) were both important in the expression of yield. Inheritance of linear regression was controlled predominantly by GCA whereas both GCA and SCA were equally important in the expression of deviation. The presence of a substantial proportion of variability due to the additive genetic component in the linear response suggests that it should be possible to exploit this fraction of variability in developing high yielding stable cultivars.

Culdoscopic ligation as an outpatient procedure

The increasing demand for abortion and sexual sterilization has caused the need to perform such operations on an outpatient basis. The University Department of Obstetrics and Gynaecology, Singapore, started a prospective study of culdoscopic ligation as an outpatient procedure in November, 1972. To date, over 600 operations have been performed. Analysis of the first 405 cases showed a low complication rate of 2.4 per cent. This study showed that culdoscopic ligation performed in the hospital outpatient is safe and feasible.