From principles to practice: a spatial approach to systematic conservation planning in the deep sea

Increases in the demand and price for industrial metals, combined with advances in technological capabilities have now made deep-sea mining more feasible and economically viable. In order to balance economic interests with the conservation of abyssal plain ecosystems, it is becoming increasingly important to develop a systematic approach to spatial management and zoning of the deep sea. Here, we describe an expert-driven systematic conservation planning process applied to inform science-based recommendations to the International Seabed Authority for a system of deep-sea marine protected areas (MPAs) to safeguard biodiversity and ecosystem function in an abyssal Pacific region targeted for nodule mining (e.g. the Clarion-Clipperton fracture zone, CCZ). Our use of geospatial analysis and expert opinion in forming the recommendations allowed us to stratify the proposed network by biophysical gradients, maximize the number of biologically unique seamounts within each subregion, and minimize socioeconomic impacts. The resulting proposal for an MPA network (nine replicate 400 × 400 km MPAs) covers 24% (1 440 000 km(2)) of the total CCZ planning region and serves as example of swift and pre-emptive conservation planning across an unprecedented area in the deep sea. As pressure from resource extraction increases in the future, the scientific guiding principles outlined in this research can serve as a basis for collaborative international approaches to ocean management.

Transient inflammation and dysfunction of the eustachian tube secondary to multiple exposures of simulated gastroesophageal refluxant

Gastroesophageal reflux is a common problem in the newborn and preschool periods. Recent research suggests that it may be related to eustachian tube dysfunction and otitis media with effusion. The purpose of this experiment was to investigate the relationship between simulated gastroesophageal reflux and eustachian tube dysfunction. Rat middle ears were repeatedly exposed (transtympanically) to pepsin in hydrochloric acid or to phosphate-buffered saline solution. Their eustachian tube function was evaluated by assessing passive opening and passive closing pressures, and active clearance of positive and negative pressure. The passive pressure function tests showed variable results. The rats exposed to pepsin in hydrochloric acid had an impaired ability to clear positive and negative pressure from the middle ear as compared to the rats exposed only to phosphate-buffered saline solution. The results demonstrate that multiple middle ear exposures to pepsin in hydrochloric acid leads to eustachian tube dysfunction in rats.

Late-phase allergy and eustachian tube dysfunction

OBJECTIVE

This study investigated the role of late-phase allergy in the development of otitis media with effusion.

METHODS

Brown Norway rats were sensitized to ovalbumin and later challenged transtympanically. Eustachian tube ventilatory function was assessed 2, 4, 8, 24, 28, and 32 hours postchallenge by measuring passive opening and closing pressures, active clearance of positive and negative middle ear pressure, and mucociliary clearance.

RESULTS

The results demonstrate that exposure to transtympanic allergen induces eustachian tube dysfunction and subsequent formation of effusion. Allergic animals showed significant increases in passive and active opening pressures, as well as a decreased ability to actively clear middle ear pressure. Finally, the mucociliary was significantly impaired in all sensitized rats exposed to transtympanic allergen.

CONCLUSION

These findings demonstrate that late-phase allergy leads to significant eustachian tube dysfunction and subsequent formation of effusion by impairing the ventilatory and clearance functions of the eustachian tube.

Function of the eustachian tube after weekly exposure to pepsin/hydrochloric acid

OBJECTIVE

To determine the effects of repeated pepsin/hydrochloric acid (HCl) exposure on the eustachian tube (ET).

STUDY DESIGN AND SETTING

ET function was studied in 22 rats. Group I (control) rats received transtympanic phosphate buffered saline solution; groups II (0.5 mg/ml) and III (2.0 mg/ml) received transtympanic pepsin/HCl. Test solutions were applied on day 0 with ET function evaluated on days 1, 2, 3, and 7 after exposure. Each 7-day period represents 1 cycle; all groups underwent 4 cycles. ET function was evaluated using passive opening and closing pressure, and active clearance of positive and negative pressure tests.

RESULTS

Rats exposed to pepsin/HCl had elevated passive opening pressures and a decreased ability to clear positive and negative pressure. A temporal relationship exists.

CONCLUSION

The results suggest middle ear exposure to pepsin/HCl leads to ET dysfunction in rats, and that this dysfunction is enhanced with repeated exposures.

SIGNIFICANCE

Gastroesophageal reflux may induce ET dysfunction.

Role of hypoxemia in sleep apnea-induced sympathoexcitation

The importance of hypoxemia in determining sympathoexcitation during obstructive sleep apnea was examined by comparing changes in efferent sympathetic nerve activity (SNA) during spontaneous obstructive apneas with hypoxemia alone of similar magnitude and duration induced by 1-4 breaths of 100% nitrogen in six patients with obstructive sleep apnea and with spontaneous apneas while breathing 100% oxygen (apnea without hypoxemia) in three patients. In addition, eight control subjects were studied during induced hypoxemia. The magnitude of sympathoexcitation during spontaneous apneas (103 +/- 15%) was more than twice that observed during induced hypoxemia (47 +/- 14%) during episodes in which the nadir of oxygen desaturation (78 +/- 2 and 75 +/- 2%, respectively) and duration of hypoxemia (27 +/- 3 and 33 +/- 3 s, respectively) were the same (P > 0.20). Similarly, in three patients SNA increased 115% during normoxic spontaneous obstructive apneas, but increased only 43% during hyperoxic spontaneous obstructive apneas in which oxygen saturation did not decrease significantly. Sympathetic neural responses to induced hypoxemia in control subjects (17 +/- 7%) were significantly less than that of the sleep apnea patients. We conclude that hypoxemia contributes importantly, but is not the sole determinant of the sympathoexcitation provoked during episodes of obstructive sleep apnea.

The effect of different carbohydrate intakes on body weight and nitrogen balance during nasogastric feeding after faciomaxillary surgery

In order to assess the effects on body composition of different carbohydrate intakes when nitrogen supply is constant and adequate (9 g/day), we gave either no carbohydrate, sufficient to avoid ketosis (100 g) or at least enough to satisfy energy needs (600 g) to a group of six patients after major faciomaxillary surgery. Each patient was given the different feeds for 3-day periods in a randomised, cross over design. 100 g carbohydrate was effective in avoiding negative nitrogen balance, but weight loss was only prevented when 600 g was used. Differences in water balance suggest that mobilisation and repletion of body glycogen (with associated water) probably account for most of these differences in body weight changes.

Prolonged nasogastric tube feeding in critically ill and surgical patients

Fifteen patients with varying diagnoses were fed via nasogastric tubes for between 7 and 41 days using a feed consisting of Caloreen (a glucose polymer) and Albumaid (a beef serum hydrolysate) with vitamin and mineral supplements. The feed proved nutritionally adequate and relatively free of complications. Diarrhoea was seen only in those patients receiving antibiotics by the nasogastric route. Codeine phosphate abolished this symptom in all patients. The constant drip method of administration proved efficient and time saving. Unlike prepacked preparations, the feed could be varied in composition to suit the clinical situation. This was of particular advantage in the intensive care context. The feed was relatively inexpensive.