Impacts of land use on Indian mangrove forest carbon stocks: Implications for conservation and management.

Globally, mangrove forests represents only 0.7% of world's tropical forested area but are highly threatened due to susceptibility to climate change, sea level rise, and increasing pressures from human population growth in coastal regions. Our study was carried out in the Bhitarkanika Conservation Area (BCA), the second-largest mangrove area in eastern India. We assessed total ecosystem carbon (C) stocks at four land use types representing varying degree of disturbances. Ranked in order of increasing impacts, these sites included dense mangrove forests, scrub mangroves, restored/planted mangroves, and abandoned aquaculture ponds. These impacts include both natural and/or anthropogenic disturbances causing stress, degradation, and destruction of mangroves. Mean vegetation C stocks (including both above- and belowground pools; mean ± standard error) in aquaculture, planted, scrub, and dense mangroves were 0, 7 ± 4, 65 ± 11 and 100 ± 11 Mg C/ha, respectively. Average soil C pools for aquaculture, planted, scrub, and dense mangroves were 61 ± 8, 92 ± 20, 177 ± 14, and 134 ± 17 Mg C/ha, respectively. Mangrove soils constituted largest fraction of total ecosystem C stocks at all sampled sites (aquaculture [100%], planted [90%], scrub [72%], and dense mangrove [57%]). Within BCA, the four studied land use types covered an area of ~167 km2 and the total ecosystem C stocks were 0.07 Tg C for aquaculture (~12 km2 ), 0.25 Tg C for planted/ restored mangrove (~24 km2 ), 2.29 teragrams (Tg) Tg C for scrub (~93 km2 ), and 0.89 Tg C for dense mangroves (~38 km2 ). Although BCA is protected under Indian wildlife protection and conservation laws, ~150 000 people inhabit this area and are directly or indirectly dependent on mangrove resources for sustenance. Estimates of C stocks of Bhitarkanika mangroves and recognition of their role as a C repository could provide an additional reason to support conservation and restoration of Bhitarkanika mangroves. Harvesting or destructive exploitation of mangroves by local communities for economic gains can potentially be minimized by enabling these communities to avail themselves of carbon offset/conservation payments under approved climate change mitigation strategies and actions.

Whole-island carbon stocks in the tropical Pacific: implications for mangrove conservation and upland restoration.

Management of forest carbon (C) stocks is an increasingly prominent land-use issue. Knowledge of carbon storage in tropical forests is improving, but regional variations are still poorly understood, and this constrains forest management and conservation efforts associated with carbon valuation mechanisms (e.g., carbon markets). This deficiency is especially pronounced in tropical islands and low-lying coastal areas where climate change impacts are expected to be among the most severe. This study presents the first field estimate of island-wide carbon storage in ecosystems of Oceania, with special attention to the regional role of coastal mangroves, which occur on islands and coastal zones throughout the tropics. On two island groups of Micronesia (Yap and Palau), we sampled all above- and belowground C pools, including soil and vegetation, in 24 sites distributed evenly among the three major vegetation structural types: mangroves, upland forests, and open savannas (generally on degraded lands formerly forested). Total C stocks were estimated to be 3.9 and 15.2 Tg C on Yap and Palau, respectively. Mangroves contained by far the largest per-hectare C pools (830-1218 Mg C ha(-1)), with deep organic-rich soils alone storing more C (631-754 Mg C ha(-1)) than all pools combined in upland systems. Despite covering just 12-13% of land area, mangroves accounted for 24-34% of total island C stocks. Savannas (156-203 Mg C ha(-1)) contained significantly lower C stocks than upland forests (375-437 Mg C ha(-1)), suggesting that reforesting savannas where appropriate has high potential for carbon-based funding to aid restoration objectives. For mangroves, these results demonstrate the key role of these systems within the broader context of C storage in island and coastal landscapes. Sustainable management of mangrove forests and their large C stocks is of high importance at the regional scale, and climate change mitigation programs such as REDD+ could play a large role in avoiding deforestation of mangroves where this is a management objective.

Neuropsychological manifestations in a case of bilateral thalamic infarction.

Neuropsychological manifestation has been reported with lesions of the anterior and non-specific thalamic nuclei and mammilothalamic tract (MMT). These have been reported in the setting of arterial infarction and/or haemorrhage. Cerebral venous sinus thrombosis (CVT) is a rare cause of brain infarction. It occurs in the setting of oral contraceptive administration or pregnancy. Inherited thrombophilias are documented risk factors. The most frequent being heterozygous factor V Leiden mutation. We report a single case of bilateral thalamic infarction due to cerebral vein and sinus thrombosis. Clinically the case manifested with memory impairment and dysexecutive symptoms. Predisposing factor for venous thrombosis was a homozygous factor V Leiden mutation. The patient was treated with anticoagulation and made a good recovery.

The frequency of perioperative vision loss.

UNLABELLED: The frequency of perioperative vision loss, especially for spinal surgery, has been increasing recently. We undertook a retrospective study to determine the frequency of this outcome in a large surgical population receiving general or central neuraxis regional anesthesia for noncardiac procedures from 1986 to 1998. Specific criteria were used to separate cases in which the surgical procedure likely directly contributed to the vision loss. Vision loss was present if any part of the visual field was affected. Initial database screening found 405 cases of new-onset vision loss or visual changes in 410,189 patients who underwent 501,342 anesthetics and who survived at least 30 days after their final procedures. Two hundred sixteen of these patients regained full vision or acuity within 30 days. Of the 189 patients who developed vision deficits for longer than 30 days, 185 underwent ophthalmologic or neurologic procedures in which ocular or cerebral tissues were surgically damaged or resected. The remaining 4 patients (1 per 125,234 overall; 0.0008%) developed prolonged vision loss without direct surgical trauma to optic or cerebral tissues. In this large study population of noncardiac surgical patients, including those who underwent spinal surgical procedures, the frequency of perioperative vision loss persisting for longer than 30 days was very small. IMPLICATIONS: Vision loss and blindness after surgery and anesthesia is a very rare event. In this study, only one per 125,234 patients undergoing noncardiac surgery developed vision loss persisting for longer than 30 days.

Beryllium-7 as a tracer of short-term sediment deposition and resuspension in the Fox River, Wisconsin.

Short-term (approximately monthly) sediment deposition and resuspension rates of surficial bed sediments in two PCB-laden impoundments on the Fox River, WI, were determined in the summer and fall of 1998 using 7Be, a naturally occurring radioisotope produced in the atmosphere. Decay-corrected activities and inventories of 7Be were measured in bed sediment and in suspended particles. Beryllium-7 activities generally decreased with depth in the top 5-10 cm of sediments and ranged from undetectable to approximately 0.9 pCi cm(-3). Inventories of 7Be, calculated from the sum of activities from all depths, ranged from 0.87 to 3.74 pCi cm(-2), and the values covaried between sites likely reflecting a common atmospheric input signal. Activities of 7Be did not correlate directly with rainfall. Partitioning the 7Be flux into "new" and "residual" components indicated that net deposition was occurring most of the time during the summer. Net erosion, however, was observed at the upstream site from the final collection in the fall. This erosion event was estimated to have removed 0.10 g (cm of sediment)(-2), corresponding to approximately 0.5 cm of sediment depth, and approximately 6-10 kg of polychlorinated biphenyls (PCBs) over the whole deposit. Short-term accumulation rates were up to approximately 130 times higher than the long-term rates calculated from 137Cs profiles, suggesting an extremely dynamic sediment transport environment, even within an impounded river system.

An electroencephalographic investigation of late-onset schizophrenia.

We performed awake and resting electroencephalograms (EEGs) on 22 subjects with DSM-III-R schizophrenic disorder of late onset (at or after age 50 years), and compared them with the EEGs of 33 healthy community controls matched for age and gender. The EEGs were rated qualitatively and a 2-minute, artifact-free tracing from each subject was quantified manually by an experienced neurophysiologist unaware of the identity of the subject group. The only significant difference was the presence of more generalized slowing in the EEGs of schizophrenia patients, which was at least partially accounted for by the effect of neuroleptic drugs. The schizophrenic subjects did not have a greater prevalence of epileptiform disturbances or abnormal asymmetry of the EEG compared to the control group. Our study does not suggest the presence of underlying dementia in schizophrenia of late onset.

Chronic intracranial hypotension.

Acute intracranial hypotension can occur following lumbar puncture or a fall, and sometimes spontaneously. Most cases resolve within weeks or months but some require surgical repair of the defect causing leakage of cerebrospinal fluid (CSF). It is conceivable that such leaks could become chronic if the defect is incompletely sealed. We report the case of a 49-year-old male who presented with a 10-month history of headache associated with a leaking thoracic extradural arachnoid cyst. After this was repaired he reported relief not only of his recent headaches but also of chronic alcohol-related headaches. A long-standing anaemia resolved and tinnitus hyperacusis improved. It is suggested that an injury 30 years before may have initiated the leak of CSF resulting in chronic intracranial hypotension.

Effects of left temporal lobectomy and amygdalohippocampectomy on memory.

This study examined the effects of left (dominant) temporal lobe surgery on verbal and visual memory in 38 patients with temporal lobe epilepsy. Twenty-five patients had anterior temporal lobectomy (ATL) and 13 had selective amygdalohippocampectomy (AH). All were administered the Rey Auditory Verbal Learning Test and a Complex Figure Test preoperatively and 1 year after surgery. ATL resulted in better seizure control overall. The ATL group as a whole showed a greater postoperative decline of their verbal memory than the AH group. A closer examination of the ATL patients showed there was a subgroup (n = 11) with better preoperative memory functioning that had the most significant decline. In contrast, only three patients in the AH group had better preoperative memory, and the majority (n = 10) matched the 'memory impaired' ATL patients. The changes in memory performance of the 'memory impaired' ATL and AH patients did not reach statistical significance. Postoperatively all patient groups improved in their verbal fluency.

Selective versus non-selective temporal lobe surgery for epilepsy.

Over a 10-year period 100 temporal lobe operations were performed for non-lesional temporal lobe epilepsy (TLE). Seventy-two patients had conventional anterior temporal lobectomy (ATL) and 28 had selective amygdalohippocampectomy (AH). Forty-three ATL patients (60%) became seizure free compared to 6 AH patients (21%) (P < 0.005). An unsatisfactory outcome was obtained in 11 (15%) ATL patients and 14 (50%) AH patients (P < 0.01). Fourteen AH patients subsequently had a second ATL procedure; 6 improved, 3 becoming seizure free. There were no differences between the two groups in the incidence of mesial temporal sclerosis (MTS) or normal pathology. However, ATL patients had a higher concordance rate of preoperative investigations which may have made them more favourable surgical candidates. It was concluded that ATL was more likely to produce a seizure free outcome than AH and should be used as the routine surgical procedure for temporal lobectomy. However, AH can give a satisfactory outcome and may be preferred when a patient has good verbal memory and all preoperative tests are concordant.

Can the interictal EEG predict successful temporal lobectomy for epilepsy?

Scalp and sphenoidal electroencephalograms (EEGs) were examined retrospectively from 45 patients who had temporal lobe surgery for epilepsy in a Comprehensive Epilepsy Programme. Interictal EEG patterns were divided into 4 groups: group 1 (18 patients) showed phase reversal of sharp (8) or spike (10) waves about one sphenoidal electrode, group 2 (11 patients) showed unilateral sharp, spike or wave activity in scalp leads only; group 3 (8 patients) showed bilateral abnormalities which were 60%; lateralized and group 4 (8 patients) showed non-lateralized changes. Lateralized EEG patterns predicted the side of subsequent surgery in all 37 cases. All 18 patients in group 1 benefited from surgery (10 seizure free at 1 year) while 20 of 27 patients in the other 3 groups benefited (13 seizure free). These results favour group 1 (P < 0.05). By comparison, the magnetic resonance image scan predicted the side of surgery in 23 of 36 (64%) patients and single photon emission tomograph scans predicted the side of surgery in 11 of 24 (46%) patients who had ictal and interictal isotope injections. Focal sphenoidal electrode discharges predict successful temporal lobectomy for surgery.

Corpus callosotomy for intractable epilepsy: seizure outcome and prognostic factors.

We reviewed the outcome of corpus callosal section in 64 adult and pediatric patients to identify factors associated with a good outcome: 48% of patients had a favorable outcome for overall seizure frequency. Improvement was noted in several seizure types and was most likely for drop attacks, particularly in the setting of a unilateral focal cerebral lesion or a true generalized epilepsy of Lennox-Gastaut type. Poor outcomes for drop attacks were more likely if there was associated severe intellectual handicap or bilateral independent spikes on interictal EEG. Complex partial seizures (CPS), most commonly of frontal lobe origin, also responded favorably. The complications of callosal section were usually mild and transient. New focal seizures occurred in only 2 patients and were not as frequent or disabling as preoperative seizures types. A worthwhile improvement in seizure outcome was achieved by completion of the callosotomy in 6 of 10 patients with unsatisfactory results from anterior callosotomy.

Surgery for refractory epilepsy.

Over a six-year period, 130 patients with medically intractable epilepsy were assessed for possible surgical treatment. Initial assessment comprised full neurological and neuropsychological examination, computed tomographic and magnetic resonance imaging brain scanning, and simultaneous video and surface plus sphenoidal electroencephalographic (EEG) recordings of typical seizures. Forty-one patients (32%) underwent further video and EEG recordings of their seizures with depth (intracerebral) or strip (subdural) electrodes. After these assessments 46 patients (35%) underwent surgery, and follow-up for six months to six years is reported in 41 patients. Of 30 patients who underwent temporal lobe surgery, 21 (70%) are free of seizures and four have had significant seizure reduction, meaning that 83% benefited from surgery. Optimal results were obtained for complex partial seizures when depth electrode recordings were obtained and when abnormal tissue was removed. Six extratemporal resections abolished seizures in two patients, and four others showed worthwhile improvement. Five patients underwent corpus callosotomy, resulting in a worthwhile improvement in three and modest improvement in two patients. No deaths or major complications occurred. It is concluded that surgical intervention can be beneficial for up to 30% of patients with medically intractable epilepsy, and referral of these patients to an appropriate institution is encouraged.

Selective epilepsy surgery in tuberous sclerosis.

A patient with tuberous sclerosis diagnosed at the age of 5 years developed an intractable seizure disorder characterized by complex partial seizures numbering 10-20/day. Interictal electroencephalograms (EEG) showed a right frontal epileptogenic focus. A computerized tomography scan demonstrated calcification in the right frontal region at two sites, periventricular calcification and multiple low density lesions. Neuropsychological assessment showed a verbal intelligence quotient (IQ) of 69 and a performance IQ of 88. Telemetry and video monitoring recorded 10 seizures during which the EEG showed flattening of ongoing sharp wave activity in the right frontal region. Electrocorticography further identified and localized epileptogenic tissue in the right frontal cortex and surgical removal of involved tissue and the adjacent two tubers was carried out. Twelve months after surgery the patient has had only two brief seizures.

Epilepsy surgery in Sturge-Weber syndrome.

A patient with Sturge-Weber syndrome developed seizures at the age of 4 years. At 13 years of age, she had intractable complex partial seizures with marked visual symptomatology. Interictal encephalograms showed bilateral slow activity, more marked over the right hemisphere with epileptogenic activity maximal in the right temporal region. Serial computerized axial tomography scans demonstrated evolution of bilateral occipital lesions with calcification and adjacent low density areas that were more marked on the right. Magnetic resonance imaging, angiography and neuropsychological evaluations were performed. An extensive resection of the right occipital lobe was achieved. One year after surgery, the patient has had seven brief seizures. Delineation of an epileptogenic focus and surgical removal of the lesion in patients with intractable seizures can now be considered in selected patients with bilateral central nervous system pathology.