Stephen N. Joffe

A comparison using the Nd-YAG laser, an ultrasonic surgical aspirator, or blunt dissection

Before gaining wide acceptance, possible surgical tools should be compared with the standard ones. This study, therefore, compared the Nd-YAG laser and the CUSA with the standard blunt dissection technique for liver resection in 24 dogs (8 in each group). Using a noncontact technique, the Nd-YAG laser was used for cutting as well as coagulation. The Nd-YAG laser or the CUSA reduced the resection time, with the laser being the faster of the two, and was accompanied by a probable but not significant decrease in perioperative blood loss. The CUSA delineated the blood vessels and bile ducts and gave superior control. It also caused significantly less tissue damage on light and electron microscopic examination than the other two methods. Cultures taken 1 week after operation showed that the risk of bacterial infection correlated well with the extent of tissue necrosis and was significantly greater after use of the Nd-YAG laser than after use of the CUSA. The numbers of animals are small and the conclusions should be tempered by caution, but it appears that the CUSA, but not the Nd-YAG laser, may improve the results of elective liver resection.

Postoperative enteral versus parenteral nutritional support in gastrointestinal surgery: A matched prospective study*

The effects of an elemental-enteral diet administered by a needle catheter jejunostomy or central total parenteral nutrition were prospectively studied in 15 patients undergoing abdominal operations. Infusions were started 1 day after operation and continued for 7 to 10 days. The two nutrient modalities were matched to deliver equal amounts of nitrogen and calories. Both promoted positive nitrogen balance and preserved body weight and serum proteins (albumin, transferrin, thyroxine-binding prealbumin, and retinol-binding protein). Both enteral and parenteral nitrogen caused a similar increase in plasma insulin levels. Pancreatic glucagon, total glucagon, gastrin, and pancreatic polypeptide were also maintained at similar levels in both groups. Plasma vasoactive intestinal polypeptide levels declined in patients receiving total parenteral nutrition but remained stable in the patients who were fed enterally. Both routes caused modest, inconsequential elevations in liver enzymes, but were otherwise equally safe. Patients tolerated total parenteral nutrition far better in the early postoperative period. Patients whose needs are great are probably better treated by total parenteral nutrition. Needle catheter jejunostomy feeding, however, is much less expensive. These studies do not support the commonly held belief that enteral nutrition is a more efficient route for administration of calories and protein.

Photoradiation therapy in early gastrointestinal cancer

Endoscopic photodynamic therapy has been used in the treatment of 19 cases of upper gastrointestinal cancer of which six were superficial esophageal and 13 were early gastric cancer. Six patients subsequently underwent surgical resection. Residual tumors were found in the resected specimens of one esophageal carcinoma and in the two early gastric carcinomas. Technical problems resulted in one failure. Follow-up ranged from 4 months to 3 years and 11 months with no tumor recurrence in either the operated or unoperated patients. Other delivery systems are currently under investigation.

The Theory Of Photodynamic Therapy Dosimetry: Consequences Of Photodestruction Of Sensitizer

Photodynamic dose is defined as the area under the curve of sensitizer level plotted as a function of light dose. The photodestruction of sensitizer during photodynamic therapy is shown to result in an upper limit on the photodynamic dose which can be delivered by an unlimited light dose. This limit results in the opportunity to make total photodynamic dose uniform to considerable depths (one to two centimeters). The existence of thresholds for permanent tissue damage allows protection of normal tissue from the large light doses required to achieve this limiting dose deep in the tissue. Higher sensitizer levels in the tumor permit tumor destruction while the normal tissues are protected. A clinical trial to determine the proper level of injected dose necessary for these results is required. This theory of photodynamic therapy (PDT) dosimetry is tested in the DBA-SMT experimental mouse tumor system. Combinations of drug and light which are not reciprocal but are nearly equal by this theory are shown to give equivalent tumor control at seven days post treatment. Reciprocal combinations of drug and light fail to give equivalent results when they are selected using the theory to choose a combination where reciprocity should fail.

Plasma and brain cholecystokinin levels in cancer anorexia

The syndrome of cancer anorexia includes early satiety in man and a reduction in the duration of feeding in experimental animals. These aberrations suggest dysfunction of peripheral and/or central nervous system satiety mechanisms in tumor-bearing individuals. Since the gut peptide, cholecystokinin (CCK), has been implicated as a potent satiety cue in man and animals, plasma and brain concentrations of CCK were measured by radioimmunoassay in anorectic tumor-bearing rats. Plasma concentrations of immunoreactive CCK were not significantly altered in either an acute Walker 256 carcinosarcoma or more chronic methylcholanthrene-induced sarcoma animal model of cancer anorexia. However, levels of immunoreactive CCK were significantly reduced in the hypothalamus and cerebral cortex of animals bearing the methylcholanthrene sarcoma during both mild and severe anorexia. These data demonstrate that elevations in immunoreactive CCK are not a major factor in the etiology of cancer anorexia. If brain CCK is involved in satiety, tumor-bearing rats may be attempting to compensate for their anorexia by down-regulating CCK production.

Pulse Width Dependence Of Pigment Cell Damage At 694 nm In Guinea Pig Skin

351 nm, 20-nsec XeF excimer laser irradiation has previously been shown to selectively target and damage melanosomes in human skin. In the following studies selective targeting with melanosomal photodisruption has been demonstrated in pigmented guinea pig skin with a Q-switched 40-nsec ruby laser, and a 750-nsec pulsed dye laser but not with a 400-usec pulsed dye laser. The pulse width dependence of melanosomal disruption, occurring only at pulsewidths shorter than the thermal relaxation time of the melanosome (0.5 - 1.0 usec), is in accordance with the theory of selective photothermolysis. Possible mechanisms of melanosomal photodisruption include development of sudden thermal gradients leading to cavitation or shock wave production.

Ultrastructure of early development of acute pancreatitis in the rat

This study was undertaken to define the earliest ultrastructural changes appearing in the exocrine pancreas and its vasculature during the development of experimental acute pancreatitis induced by the closed duodenal loop technique. Experimental and shamoperated rats were killed at hourly intervals up to 4 hr and at 6 hr postoperatively. Focal acinar cell response included appearance of vacuoles containing uncondensed or partially condensed secretory product, and some rearrangement and dilatation of the rough endoplasmic reticulum within 1 hr. Mild edema was observed and damage to the vascular endothelium developed by 2 hr. At 4 hr focal hemorrhage and a slight inflammatory cell infiltrate was noted which was more prominent at 6 hr. The lack of a correspondence between areas of acinar cell and of vascular abnormalities suggests that factors other than increased secretory back-pressure are involved in the early development of this model of acute pancreatitis.

The Effect of Parenteral and Enteral Nutrition on Portal and Systemic Immunoreactivities of Gastrin, Glucagon and Vasoactive Intestinal Polypeptide (VIP)

To compare the effect of parenteral with enteral nutrition on gastroentero-pancreatic hormones, hypercaloric and hypocaloric nutrient preparations, commonly used clinically, were administered to rats either through cannulae in the jugular vein or gastrostomies. Control rats were fed orally ad libitum. Portal and aortic plasma was collected for radioimmunoassay with antibodies to C-terminal regions of gastrin and glucagon and to N-terminal-to-central regions of glucagon and VIP. Levels of all immunoreactivities were significantly lower in aortic than portal plasma. Apparent clearance of glucagon and gastrin by liver or lung or both was enhanced by administration of the hypercaloric nutrient intravenously. Only intragastric hypercaloric nutrition maintained levels of VIP immunoreactivity close to those of control rats. Intragastric administration of either preparation appeared to maintain adequate levels of gastrin. Differences in the levels of glucagon immunoreactivities may be related to the stimulatory effects of metabolites in the lower gut and pancreas.

Morphologic and functional evidence of reinnervation of the gastric parietal cell mass after parietal cell vagotomy

The incidence of recurrent ulceration after parietal cell vagotomy varies greatly and the cause is largely unknown. Whether the vagus nerve can regenerate or reinnervate the gastric parietal cell mass after parietal cell vagotomy was investigated. Careful microscopic dissection of the neurovascular bundle in 130 rats allowed the vagus nerve to be divided to the gastric body with preservation of the antropyloric nerve and gastric vasculature. Gastric secretory tests were performed under basal and stimulated conditions after secretagogue and insulin hypoglycemia stimulation. Rats were killed weekly and the vagal nerve distribution examined by electron microscopy. Stimulated gastric acid output decreased from 164 to 26 mumol/hour immediately after operation (p less than 0.001). One week after parietal cell vagotomy the nerves were swollen with fibroblast infiltration and collagen around axon groups showed degeneration. By the third week after parietal cell vagotomy, the axons were more densely packed with neurofilaments and acid output had increased to 183 mumol/hour. In the fourth and fifth weeks, the enlarged Schwann cell processes had more axons and acid output increased to 262 mumol/hour. By the seventh week, both large and small axons were identified and the acid output was 93 percent higher than the preoperative level (p less than 0.001). The sequential neuropathologic changes of vagus nerve degeneration, regeneration and functional reinnervation of the gastric parietal cell mass after parietal cell vagotomy are shown by this study. If this occurs in man, it may be an important cause of recurrent peptic ulceration after parietal cell vagotomy.

Argon Laser Vascular Welding: The Thermal Component

Various mechanisms have been proposed for laser induced vascular welding. The conflict is partly due to the different laser parameters being used, different techniques, and the possible dual thermal and photochemical effects of lasers on tissues. This study examines the thermal aspects of welding medium diameter (4-8 mm) blood vessels. Six canine arteriovenous (A-V) fistulas were created by argon laser vessel fusion. Thermal images were concurrently recorded with a AGA thermal camera and computer analyzed. The welding was done at an energy fluence of 1100 J/cm2, using continuous saline irrigation for cooling. The thermal profiles revealed a maximum temperature of 48° C. In previous experiments, welding of microvessels has been achieved with CO2 , Na:YAG and argon lasers. In our experience, welding of medium diameter arteriotomies and A-V fistulas was possible only with argon lasers. The thermal component induced by different laser wavelengths may be partly accountable for these observed differences in welding properties. Further studies are required to delineate the role of photochemical and thermal reactions in vascular tissue fusion by lasers.